subject:"Equivalence"



On Thursday, July 23, 2020 at 8:56:03 PM UTC-6, Alan Grayson wrote:
>
>
>
> On Thursday, July 23, 2020 at 11:59:59 AM UTC-6, Brent wrote:
>>
>>
>>
>> On 7/23/2020 4:41 AM, Lawrence Crowell wrote:
>>
>> On Thursday, July 23, 2020 at 5:56:32 AM UTC-5 agrays...@gmail.com wrote:
>>
>>>
>>>
>>> On Saturday, July 18, 2020 at 6:31:23 AM UTC-6, Alan Grayson wrote: 



 On Saturday, July 18, 2020 at 6:18:28 AM UTC-6, Lawrence Crowell wrote: 
>
> The tortoise coordinates is found from the Schwarzschild metric 
>
> ds^2 = (1 - 2m/r)dt^2 -  (1 - 2m/r)^{-1}dr^2 - r^2dΩ^2   
>
> where for a signal leaving a point near the black hole with ds = 0 
> (null path) and propagating radially out, dΩ = 0, we have dt = dr/(1 - 
> 2m/r) which then leads to
>
> T = t - t0 - 2m ln|r - 2m|.
>
> That is the tortoise coordinate. Please look this up to read further. 
> I can't spend beaucoup time going over this for weeks to come.
>
> LC
>

 You don't have to. We're done.  But you should IMO address Brent's 
 objection, maybe on another thread. AG

>>>
>> I don't know what objection you're referring to.  LC is just showing why 
>> it takes a distant observer forever to see an infalling object reach the 
>> event horizon of a black hole.
>>
>> Brent
>>
>
> Your words: 
>
> I wonder about the use of cicumlocutions like "from the perspective of an 
> outside observer".  In special relativity it it is often said that a moving 
> object will looked shortened along the direction of motion.  But as Terrell 
> pointed out that's not at all how they look.  It is more accurate to say 
> that *measuring* a moving a object will show that it is shortened along 
> the direction of motion; the difference being that the measurement corrects 
> for the fact that you want the difference in arrival time of photons that 
> left the ends of the object at the same time (an ill defined concept), 
> instead of the image formed by photons that arrived at the same time.  But 
> then I think, why not correct for the Lorentz contraction too in the 
> measurement and arrive at what we might call "the proper length".  That's 
> just as "measured" as either of the other two.
>
> By the same reasoning, you're really saying the visual impression of a 
> distant observer is that infalling stuff appears to be on the surface of 
> the event horizon. Which is because it takes forever for photons to reach 
> him.  But why should he be so naive.  He knows what he's seeing is 
> arbitrarily far in his past; so what he should be said to "measure" or 
> "calculate" is that the stuff has already been annihilated at the 
> "singularity" in his reference frame.
>
> -
>
> I forget why LC brought up this particular coordinate system. He had some 
> point in response to a comment I made. I'll have to review my comments; 
> maybe that the gravitational field due to a BH, external to the event 
> horizon, has an objective reality. AG
>

I just reviewed LC's comments. He was claiming that tortoise coordinates 
show the existence of the gravitational field due to a BH, external to it. 
He wasn't limiting his argument, which you apparently objected to, to how 
long a distant observer would have to view an infalling mass, to see it 
disappear. AG 

>
>  
>
>>
>>
>>> When it comes to GR, you're a genius; no question about it. I wouldn't 
>>> want to waste your valuable time. But consider this; the Schwartzschild 
>>> metric applies to NON-ROTATING masses. Do you really think a massive 
>>> contracting star which forms a BH will be non-rotating? Obviously, it will 
>>> be RAPIDLY rotating, like an ice skater who contracts her arms. Brent also 
>>> had some substantive questions about your model. But I see you prefer your 
>>> illusions than to address his objections. AG
>>>
>>
>> The result is similar, but more complex. The same calculation can be done 
>> for the Kerr solution. It is just a lot more complicated mathematically.
>>
>> LC
>>  
>> -- 
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>>  
>> 
>> .
>>
>>
>>

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Re: Principle of Equivalence

On Thursday, July 23, 2020 at 11:59:59 AM UTC-6, Brent wrote:
>
>
>
> On 7/23/2020 4:41 AM, Lawrence Crowell wrote:
>
> On Thursday, July 23, 2020 at 5:56:32 AM UTC-5 agrays...@gmail.com wrote:
>
>>
>>
>> On Saturday, July 18, 2020 at 6:31:23 AM UTC-6, Alan Grayson wrote: 
>>>
>>>
>>>
>>> On Saturday, July 18, 2020 at 6:18:28 AM UTC-6, Lawrence Crowell wrote: 

 The tortoise coordinates is found from the Schwarzschild metric 

 ds^2 = (1 - 2m/r)dt^2 -  (1 - 2m/r)^{-1}dr^2 - r^2dΩ^2   

 where for a signal leaving a point near the black hole with ds = 0 
 (null path) and propagating radially out, dΩ = 0, we have dt = dr/(1 - 
 2m/r) which then leads to

 T = t - t0 - 2m ln|r - 2m|.

 That is the tortoise coordinate. Please look this up to read further. I 
 can't spend beaucoup time going over this for weeks to come.

 LC

>>>
>>> You don't have to. We're done.  But you should IMO address Brent's 
>>> objection, maybe on another thread. AG
>>>
>>
> I don't know what objection you're referring to.  LC is just showing why 
> it takes a distant observer forever to see an infalling object reach the 
> event horizon of a black hole.
>
> Brent
>

Your words: 

I wonder about the use of cicumlocutions like "from the perspective of an 
outside observer".  In special relativity it it is often said that a moving 
object will looked shortened along the direction of motion.  But as Terrell 
pointed out that's not at all how they look.  It is more accurate to say 
that *measuring* a moving a object will show that it is shortened along the 
direction of motion; the difference being that the measurement corrects for 
the fact that you want the difference in arrival time of photons that left 
the ends of the object at the same time (an ill defined concept), instead 
of the image formed by photons that arrived at the same time.  But then I 
think, why not correct for the Lorentz contraction too in the measurement 
and arrive at what we might call "the proper length".  That's just as 
"measured" as either of the other two.

By the same reasoning, you're really saying the visual impression of a 
distant observer is that infalling stuff appears to be on the surface of 
the event horizon. Which is because it takes forever for photons to reach 
him.  But why should he be so naive.  He knows what he's seeing is 
arbitrarily far in his past; so what he should be said to "measure" or 
"calculate" is that the stuff has already been annihilated at the 
"singularity" in his reference frame.

-

I forget why LC brought up this particular coordinate system. He had some 
point in response to a comment I made. I'll have to review my comments; 
maybe that the gravitational field due to a BH, external to the event 
horizon, has an objective reality. AG

>
>
>> When it comes to GR, you're a genius; no question about it. I wouldn't 
>> want to waste your valuable time. But consider this; the Schwartzschild 
>> metric applies to NON-ROTATING masses. Do you really think a massive 
>> contracting star which forms a BH will be non-rotating? Obviously, it will 
>> be RAPIDLY rotating, like an ice skater who contracts her arms. Brent also 
>> had some substantive questions about your model. But I see you prefer your 
>> illusions than to address his objections. AG
>>
>
> The result is similar, but more complex. The same calculation can be done 
> for the Kerr solution. It is just a lot more complicated mathematically.
>
> LC
>  
> -- 
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> "Everything List" group.
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>  
> 
> .
>
>
>

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Re: Principle of Equivalence

2020-07-23 Thread 'Brent Meeker' via Everything List

On 7/23/2020 7:33 AM, Alan Grayson wrote:

On Thursday, July 23, 2020 at 8:27:52 AM UTC-6, Lawrence Crowell wrote:

Coordinates are not the basis of physics. Curvatures are
covariant, while connections and coordinates are not. These can be
imposed in many ways, similar to a gauge choice.

That right; coordinates are not the basis of physics. That's why
Einstein had to cast his GR equation in tensor form, so the laws of
physics would be independent of coordinate systems. But you're
asserting, or so it seems, that there is a unique coordinate system
wherein the external gravitational effect of a BH can be calculated.
This is what I object to. AG

Calculations are always done in some coordinate system. The method is
to calculate something, like the curvature tensor or a proper time, that
doesn't depend on which coordinate system you used.

Brent

On Thursday, July 23, 2020 at 6:49:44 AM UTC-5 agrays...@gmail.com
wrote:

On Thursday, July 23, 2020 at 5:41:42 AM UTC-6, Lawrence
Crowell wrote:

On Thursday, July 23, 2020 at 5:56:32 AM UTC-5
agrays...@gmail.com wrote:

On Saturday, July 18, 2020 at 6:31:23 AM UTC-6, Alan
Grayson wrote:

On Saturday, July 18, 2020 at 6:18:28 AM UTC-6,
Lawrence Crowell wrote:

The tortoise coordinates is found from the
Schwarzschild metric

ds^2 = (1 - 2m/r)dt^2 - (1 - 2m/r)^{-1}dr^2 -
r^2dΩ^2

where for a signal leaving a point near the
black hole with ds = 0 (null path) and
propagating radially out, dΩ = 0, we have dt =
dr/(1 - 2m/r) which then leads to

T = t - t0 - 2m ln|r - 2m|.

That is the tortoise coordinate. Please look
this up to read further. I can't spend
beaucoup time going over this for weeks to come.

You don't have to. We're done. But you should IMO
address Brent's objection, maybe on another thread. AG

When it comes to GR, you're a genius; no question
about it. I wouldn't want to waste your valuable time.
But consider this; the Schwartzschild metric applies
to NON-ROTATING masses. Do you really think a massive
contracting star which forms a BH will be
non-rotating? Obviously, it will be RAPIDLY rotating,
like an ice skater who contracts her arms. Brent also
had some substantive questions about your model. But I
see you prefer your illusions than to address his
objections. AG

The result is similar, but more complex. The same
calculation can be done for the Kerr solution. It is just
a lot more complicated mathematically.

If you say so. In any event, the idea that an objectively
existing gravitational field outside a BH should depend on the
choice of a particular coordinate system, seems a non-starter. AG

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Re: Principle of Equivalence

2020-07-23 Thread 'Brent Meeker' via Everything List

On 7/23/2020 4:41 AM, Lawrence Crowell wrote:

On Thursday, July 23, 2020 at 5:56:32 AM UTC-5 agrays...@gmail.com wrote:

On Saturday, July 18, 2020 at 6:31:23 AM UTC-6, Alan Grayson wrote:

On Saturday, July 18, 2020 at 6:18:28 AM UTC-6, Lawrence
Crowell wrote:

The tortoise coordinates is found from the Schwarzschild
metric

ds^2 = (1 - 2m/r)dt^2 - (1 - 2m/r)^{-1}dr^2 - r^2dΩ^2

where for a signal leaving a point near the black hole
with ds = 0 (null path) and propagating radially out, dΩ =
0, we have dt = dr/(1 - 2m/r) which then leads to

T = t - t0 - 2m ln|r - 2m|.

That is the tortoise coordinate. Please look this up to
read further. I can't spend beaucoup time going over this
for weeks to come.

You don't have to. We're done. But you should IMO address
Brent's objection, maybe on another thread. AG

I don't know what objection you're referring to. LC is just showing why
it takes a distant observer forever to see an infalling object reach the
event horizon of a black hole.

Brent

When it comes to GR, you're a genius; no question about it. I
wouldn't want to waste your valuable time. But consider this; the
Schwartzschild metric applies to NON-ROTATING masses. Do you
really think a massive contracting star which forms a BH will be
non-rotating? Obviously, it will be RAPIDLY rotating, like an ice
skater who contracts her arms. Brent also had some substantive
questions about your model. But I see you prefer your illusions
than to address his objections. AG

The result is similar, but more complex. The same calculation can be
done for the Kerr solution. It is just a lot more complicated
mathematically.

LC
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Re: Principle of Equivalence



On Thursday, July 23, 2020 at 8:27:52 AM UTC-6, Lawrence Crowell wrote:
>
> Coordinates are not the basis of physics. Curvatures are covariant, while 
> connections and coordinates are not. These can be imposed in many ways, 
> similar to a gauge choice. 
>
> LC
>

That right; coordinates are not the basis of physics. That's why Einstein 
had to cast his GR equation in tensor form, so the laws of physics would be 
independent of coordinate systems. But you're asserting, or so it seems, 
that there is a unique coordinate system wherein the external gravitational 
effect of a BH can be calculated. This is what I object to. AG

>
>
> On Thursday, July 23, 2020 at 6:49:44 AM UTC-5 agrays...@gmail.com wrote:
>
>>
>>
>> On Thursday, July 23, 2020 at 5:41:42 AM UTC-6, Lawrence Crowell wrote:
>>>
>>> On Thursday, July 23, 2020 at 5:56:32 AM UTC-5 agrays...@gmail.com 
>>> wrote:
>>>


 On Saturday, July 18, 2020 at 6:31:23 AM UTC-6, Alan Grayson wrote:
>
>
>
> On Saturday, July 18, 2020 at 6:18:28 AM UTC-6, Lawrence Crowell wrote:
>>
>> The tortoise coordinates is found from the Schwarzschild metric
>>
>> ds^2 = (1 - 2m/r)dt^2 -  (1 - 2m/r)^{-1}dr^2 - r^2dΩ^2   
>>
>> where for a signal leaving a point near the black hole with ds = 0 
>> (null path) and propagating radially out, dΩ = 0, we have dt = dr/(1 - 
>> 2m/r) which then leads to
>>
>> T = t - t0 - 2m ln|r - 2m|.
>>
>> That is the tortoise coordinate. Please look this up to read further. 
>> I can't spend beaucoup time going over this for weeks to come.
>>
>> LC
>>
>
> You don't have to. We're done.  But you should IMO address Brent's 
> objection, maybe on another thread. AG
>

 When it comes to GR, you're a genius; no question about it. I wouldn't 
 want to waste your valuable time. But consider this; the Schwartzschild 
 metric applies to NON-ROTATING masses. Do you really think a massive 
 contracting star which forms a BH will be non-rotating? Obviously, it will 
 be RAPIDLY rotating, like an ice skater who contracts her arms. Brent also 
 had some substantive questions about your model. But I see you prefer your 
 illusions than to address his objections. AG

>>>
>>> The result is similar, but more complex. The same calculation can be 
>>> done for the Kerr solution. It is just a lot more complicated 
>>> mathematically.
>>>
>>> LC
>>>
>>
>> If you say so. In any event, the idea that an objectively existing 
>> gravitational field outside a BH should depend on the choice of a 
>> particular coordinate system, seems a non-starter. AG 
>>
>>>  
>>>
>>

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Re: Principle of Equivalence

2020-07-23 Thread Lawrence Crowell

Coordinates are not the basis of physics. Curvatures are covariant, while 
connections and coordinates are not. These can be imposed in many ways, 
similar to a gauge choice. 

LC

On Thursday, July 23, 2020 at 6:49:44 AM UTC-5 agrays...@gmail.com wrote:

>
>
> On Thursday, July 23, 2020 at 5:41:42 AM UTC-6, Lawrence Crowell wrote:
>>
>> On Thursday, July 23, 2020 at 5:56:32 AM UTC-5 agrays...@gmail.com wrote:
>>
>>>
>>>
>>> On Saturday, July 18, 2020 at 6:31:23 AM UTC-6, Alan Grayson wrote:



 On Saturday, July 18, 2020 at 6:18:28 AM UTC-6, Lawrence Crowell wrote:
>
> The tortoise coordinates is found from the Schwarzschild metric
>
> ds^2 = (1 - 2m/r)dt^2 -  (1 - 2m/r)^{-1}dr^2 - r^2dΩ^2   
>
> where for a signal leaving a point near the black hole with ds = 0 
> (null path) and propagating radially out, dΩ = 0, we have dt = dr/(1 - 
> 2m/r) which then leads to
>
> T = t - t0 - 2m ln|r - 2m|.
>
> That is the tortoise coordinate. Please look this up to read further. 
> I can't spend beaucoup time going over this for weeks to come.
>
> LC
>

 You don't have to. We're done.  But you should IMO address Brent's 
 objection, maybe on another thread. AG

>>>
>>> When it comes to GR, you're a genius; no question about it. I wouldn't 
>>> want to waste your valuable time. But consider this; the Schwartzschild 
>>> metric applies to NON-ROTATING masses. Do you really think a massive 
>>> contracting star which forms a BH will be non-rotating? Obviously, it will 
>>> be RAPIDLY rotating, like an ice skater who contracts her arms. Brent also 
>>> had some substantive questions about your model. But I see you prefer your 
>>> illusions than to address his objections. AG
>>>
>>
>> The result is similar, but more complex. The same calculation can be done 
>> for the Kerr solution. It is just a lot more complicated mathematically.
>>
>> LC
>>
>
> If you say so. In any event, the idea that an objectively existing 
> gravitational field outside a BH should depend on the choice of a 
> particular coordinate system, seems a non-starter. AG 
>
>>  
>>
>

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Re: Principle of Equivalence



On Thursday, July 23, 2020 at 5:41:42 AM UTC-6, Lawrence Crowell wrote:
>
> On Thursday, July 23, 2020 at 5:56:32 AM UTC-5 agrays...@gmail.com wrote:
>
>>
>>
>> On Saturday, July 18, 2020 at 6:31:23 AM UTC-6, Alan Grayson wrote:
>>>
>>>
>>>
>>> On Saturday, July 18, 2020 at 6:18:28 AM UTC-6, Lawrence Crowell wrote:

 The tortoise coordinates is found from the Schwarzschild metric

 ds^2 = (1 - 2m/r)dt^2 -  (1 - 2m/r)^{-1}dr^2 - r^2dΩ^2   

 where for a signal leaving a point near the black hole with ds = 0 
 (null path) and propagating radially out, dΩ = 0, we have dt = dr/(1 - 
 2m/r) which then leads to

 T = t - t0 - 2m ln|r - 2m|.

 That is the tortoise coordinate. Please look this up to read further. I 
 can't spend beaucoup time going over this for weeks to come.

 LC

>>>
>>> You don't have to. We're done.  But you should IMO address Brent's 
>>> objection, maybe on another thread. AG
>>>
>>
>> When it comes to GR, you're a genius; no question about it. I wouldn't 
>> want to waste your valuable time. But consider this; the Schwartzschild 
>> metric applies to NON-ROTATING masses. Do you really think a massive 
>> contracting star which forms a BH will be non-rotating? Obviously, it will 
>> be RAPIDLY rotating, like an ice skater who contracts her arms. Brent also 
>> had some substantive questions about your model. But I see you prefer your 
>> illusions than to address his objections. AG
>>
>
> The result is similar, but more complex. The same calculation can be done 
> for the Kerr solution. It is just a lot more complicated mathematically.
>
> LC
>

If you say so. In any event, the idea that an objectively existing 
gravitational field outside a BH should depend on the choice of a 
particular coordinate system, seems a non-starter. AG 

>  
>

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Re: Principle of Equivalence

2020-07-23 Thread Lawrence Crowell

On Thursday, July 23, 2020 at 5:56:32 AM UTC-5 agrays...@gmail.com wrote:

>
>
> On Saturday, July 18, 2020 at 6:31:23 AM UTC-6, Alan Grayson wrote:
>>
>>
>>
>> On Saturday, July 18, 2020 at 6:18:28 AM UTC-6, Lawrence Crowell wrote:
>>>
>>> The tortoise coordinates is found from the Schwarzschild metric
>>>
>>> ds^2 = (1 - 2m/r)dt^2 -  (1 - 2m/r)^{-1}dr^2 - r^2dΩ^2   
>>>
>>> where for a signal leaving a point near the black hole with ds = 0 (null 
>>> path) and propagating radially out, dΩ = 0, we have dt = dr/(1 - 2m/r) 
>>> which then leads to
>>>
>>> T = t - t0 - 2m ln|r - 2m|.
>>>
>>> That is the tortoise coordinate. Please look this up to read further. I 
>>> can't spend beaucoup time going over this for weeks to come.
>>>
>>> LC
>>>
>>
>> You don't have to. We're done.  But you should IMO address Brent's 
>> objection, maybe on another thread. AG
>>
>
> When it comes to GR, you're a genius; no question about it. I wouldn't 
> want to waste your valuable time. But consider this; the Schwartzschild 
> metric applies to NON-ROTATING masses. Do you really think a massive 
> contracting star which forms a BH will be non-rotating? Obviously, it will 
> be RAPIDLY rotating, like an ice skater who contracts her arms. Brent also 
> had some substantive questions about your model. But I see you prefer your 
> illusions than to address his objections. AG
>

The result is similar, but more complex. The same calculation can be done 
for the Kerr solution. It is just a lot more complicated mathematically.

LC
 

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Re: Principle of Equivalence



On Saturday, July 18, 2020 at 6:31:23 AM UTC-6, Alan Grayson wrote:
>
>
>
> On Saturday, July 18, 2020 at 6:18:28 AM UTC-6, Lawrence Crowell wrote:
>>
>> The tortoise coordinates is found from the Schwarzschild metric
>>
>> ds^2 = (1 - 2m/r)dt^2 -  (1 - 2m/r)^{-1}dr^2 - r^2dΩ^2   
>>
>> where for a signal leaving a point near the black hole with ds = 0 (null 
>> path) and propagating radially out, dΩ = 0, we have dt = dr/(1 - 2m/r) 
>> which then leads to
>>
>> T = t - t0 - 2m ln|r - 2m|.
>>
>> That is the tortoise coordinate. Please look this up to read further. I 
>> can't spend beaucoup time going over this for weeks to come.
>>
>> LC
>>
>
> You don't have to. We're done.  But you should IMO address Brent's 
> objection, maybe on another thread. AG
>

When it comes to GR, you're a genius; no question about it. I wouldn't want 
to waste your valuable time. But consider this; the Schwartzschild metric 
applies to NON-ROTATING masses. Do you really think a massive contracting 
star which forms a BH will be non-rotating? Obviously, it will be RAPIDLY 
rotating, like an ice skater who contracts her arms. Brent also had some 
substantive questions about your model. But I see you prefer your illusions 
than to address his objections. AG

>
>> On Friday, July 17, 2020 at 11:08:00 PM UTC-5 agrays...@gmail.com wrote:
>>
>>>
>>>
>>> On Friday, July 17, 2020 at 11:54:20 AM UTC-6, Lawrence Crowell wrote:

 On Friday, July 17, 2020 at 11:43:48 AM UTC-5 agrays...@gmail.com 
 wrote:

>
>
> On Friday, July 17, 2020 at 5:34:17 AM UTC-6, Alan Grayson wrote:
>>
>>
>>
>> On Friday, July 17, 2020 at 4:48:51 AM UTC-6, Lawrence Crowell wrote:
>>>
>>> On Friday, July 17, 2020 at 5:01:41 AM UTC-5 agrays...@gmail.com 
>>> wrote:
>>>


 On Thursday, July 16, 2020 at 7:50:07 PM UTC-6, Alan Grayson wrote:
>
>
>
> On Thursday, July 16, 2020 at 5:08:57 PM UTC-6, Lawrence Crowell 
> wrote:
>>
>> Gravitons do not escape from a BH, any more than can light. 
>> However, from the perspective of an outside observer all matter than 
>> went 
>> into a BH is on the surface above the event horizon, called the 
>> stretched 
>> horizon. 
>>
>> LC
>>
>
> Gravitons might not exist (and hence quantum gravity can't exist)  
> But whatever the case, how can BH's interact gravitationally with 
> objects 
> beyond its event horizon? You say this doesn't happen. I don't 
> understand 
> your argument. AG 
>

>>> That you are saying this illustrates you do not understand general 
>>> relativity.
>>>  
>>>

 I may have identified the thousand pound gorilla in the room; the 
 hypothetical force carrying particle of the quantum gravitating field, 
 the 
 graviton, which for BH's doesn't exert any force! AG 

>>>
>>> I have no idea why you are saying this. Gravitation is not a force 
>>> in the usual sense and so the graviton does not produce a force in the 
>>> standard meaning. For the weak field limit the nonlinear terms are 
>>> negligable and a gravitational wave is linear. This is easily 
>>> quantized. In 
>>> fact it is similar to the Hanbury-Brown and Twiss theory of the 
>>> diphoton. 
>>> It is when the field becomes strong that general relativity becomes 
>>> nonlinear and runs into trouble with quantum mechanics.
>>>
>>> LC
>>>
>>
>> I assumed a quantum field theory of gravity must have a particle 
>> associated with it, and that this particle is called the graviton. 
>> Gravity 
>> is a fictitious force. So what would the role of the graviton be, if not 
>> to 
>> produce some force? If you detect gravitational waves, don't they 
>> consist 
>> of gravitons if a quantum theory of gravity exists, analogous to photons 
>> in 
>> EM waves? AG
>>
>
> Before you can present yourself as deeply knowledgeable of GR, you 
> should be able to give a coherent account how presumably *isolated* 
> bodies such as BH's, can gravitationally interact with what's exterior to 
> them. If gravitons can't do that in the context of a quantum theory of 
> gravity, what can?  AG
>

 It is the delay or tortoise coordinate basis for an external observer.

>>>
>>> This is a tough subject to wrap one's head around. Wiki has a decent 
>>> article on it. There's an objective gravitational effect of a BH beyond its 
>>> event horizon. Are you claiming that the effect is only supported by theory 
>>> by a particular choice of coordinate system for an external observer? AG 
>>>

 LC 

>>>

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Re: Principle of Equivalence

2020-07-18 Thread Alan Grayson



On Saturday, July 18, 2020 at 6:18:28 AM UTC-6, Lawrence Crowell wrote:
>
> The tortoise coordinates is found from the Schwarzschild metric
>
> ds^2 = (1 - 2m/r)dt^2 -  (1 - 2m/r)^{-1}dr^2 - r^2dΩ^2   
>
> where for a signal leaving a point near the black hole with ds = 0 (null 
> path) and propagating radially out, dΩ = 0, we have dt = dr/(1 - 2m/r) 
> which then leads to
>
> T = t - t0 - 2m ln|r - 2m|.
>
> That is the tortoise coordinate. Please look this up to read further. I 
> can't spend beaucoup time going over this for weeks to come.
>
> LC
>

You don't have to. We're done.  But you should IMO address Brent's 
objection, maybe on another thread. AG


> On Friday, July 17, 2020 at 11:08:00 PM UTC-5 agrays...@gmail.com wrote:
>
>>
>>
>> On Friday, July 17, 2020 at 11:54:20 AM UTC-6, Lawrence Crowell wrote:
>>>
>>> On Friday, July 17, 2020 at 11:43:48 AM UTC-5 agrays...@gmail.com wrote:
>>>


 On Friday, July 17, 2020 at 5:34:17 AM UTC-6, Alan Grayson wrote:
>
>
>
> On Friday, July 17, 2020 at 4:48:51 AM UTC-6, Lawrence Crowell wrote:
>>
>> On Friday, July 17, 2020 at 5:01:41 AM UTC-5 agrays...@gmail.com 
>> wrote:
>>
>>>
>>>
>>> On Thursday, July 16, 2020 at 7:50:07 PM UTC-6, Alan Grayson wrote:



 On Thursday, July 16, 2020 at 5:08:57 PM UTC-6, Lawrence Crowell 
 wrote:
>
> Gravitons do not escape from a BH, any more than can light. 
> However, from the perspective of an outside observer all matter than 
> went 
> into a BH is on the surface above the event horizon, called the 
> stretched 
> horizon. 
>
> LC
>

 Gravitons might not exist (and hence quantum gravity can't exist)  
 But whatever the case, how can BH's interact gravitationally with 
 objects 
 beyond its event horizon? You say this doesn't happen. I don't 
 understand 
 your argument. AG 

>>>
>> That you are saying this illustrates you do not understand general 
>> relativity.
>>  
>>
>>>
>>> I may have identified the thousand pound gorilla in the room; the 
>>> hypothetical force carrying particle of the quantum gravitating field, 
>>> the 
>>> graviton, which for BH's doesn't exert any force! AG 
>>>
>>
>> I have no idea why you are saying this. Gravitation is not a force in 
>> the usual sense and so the graviton does not produce a force in the 
>> standard meaning. For the weak field limit the nonlinear terms are 
>> negligable and a gravitational wave is linear. This is easily quantized. 
>> In 
>> fact it is similar to the Hanbury-Brown and Twiss theory of the 
>> diphoton. 
>> It is when the field becomes strong that general relativity becomes 
>> nonlinear and runs into trouble with quantum mechanics.
>>
>> LC
>>
>
> I assumed a quantum field theory of gravity must have a particle 
> associated with it, and that this particle is called the graviton. 
> Gravity 
> is a fictitious force. So what would the role of the graviton be, if not 
> to 
> produce some force? If you detect gravitational waves, don't they consist 
> of gravitons if a quantum theory of gravity exists, analogous to photons 
> in 
> EM waves? AG
>

 Before you can present yourself as deeply knowledgeable of GR, you 
 should be able to give a coherent account how presumably *isolated* 
 bodies such as BH's, can gravitationally interact with what's exterior to 
 them. If gravitons can't do that in the context of a quantum theory of 
 gravity, what can?  AG

>>>
>>> It is the delay or tortoise coordinate basis for an external observer.
>>>
>>
>> This is a tough subject to wrap one's head around. Wiki has a decent 
>> article on it. There's an objective gravitational effect of a BH beyond its 
>> event horizon. Are you claiming that the effect is only supported by theory 
>> by a particular choice of coordinate system for an external observer? AG 
>>
>>>
>>> LC 
>>>
>>

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Re: Principle of Equivalence

2020-07-18 Thread Lawrence Crowell

The tortoise coordinates is found from the Schwarzschild metric

ds^2 = (1 - 2m/r)dt^2 -  (1 - 2m/r)^{-1}dr^2 - r^2dΩ^2   

where for a signal leaving a point near the black hole with ds = 0 (null 
path) and propagating radially out, dΩ = 0, we have dt = dr/(1 - 2m/r) 
which then leads to

T = t - t0 - 2m ln|r - 2m|.

That is the tortoise coordinate. Please look this up to read further. I 
can't spend beaucoup time going over this for weeks to come.

LC

On Friday, July 17, 2020 at 11:08:00 PM UTC-5 agrays...@gmail.com wrote:

>
>
> On Friday, July 17, 2020 at 11:54:20 AM UTC-6, Lawrence Crowell wrote:
>>
>> On Friday, July 17, 2020 at 11:43:48 AM UTC-5 agrays...@gmail.com wrote:
>>
>>>
>>>
>>> On Friday, July 17, 2020 at 5:34:17 AM UTC-6, Alan Grayson wrote:



 On Friday, July 17, 2020 at 4:48:51 AM UTC-6, Lawrence Crowell wrote:
>
> On Friday, July 17, 2020 at 5:01:41 AM UTC-5 agrays...@gmail.com 
> wrote:
>
>>
>>
>> On Thursday, July 16, 2020 at 7:50:07 PM UTC-6, Alan Grayson wrote:
>>>
>>>
>>>
>>> On Thursday, July 16, 2020 at 5:08:57 PM UTC-6, Lawrence Crowell 
>>> wrote:

 Gravitons do not escape from a BH, any more than can light. 
 However, from the perspective of an outside observer all matter than 
 went 
 into a BH is on the surface above the event horizon, called the 
 stretched 
 horizon. 

 LC

>>>
>>> Gravitons might not exist (and hence quantum gravity can't exist)  
>>> But whatever the case, how can BH's interact gravitationally with 
>>> objects 
>>> beyond its event horizon? You say this doesn't happen. I don't 
>>> understand 
>>> your argument. AG 
>>>
>>
> That you are saying this illustrates you do not understand general 
> relativity.
>  
>
>>
>> I may have identified the thousand pound gorilla in the room; the 
>> hypothetical force carrying particle of the quantum gravitating field, 
>> the 
>> graviton, which for BH's doesn't exert any force! AG 
>>
>
> I have no idea why you are saying this. Gravitation is not a force in 
> the usual sense and so the graviton does not produce a force in the 
> standard meaning. For the weak field limit the nonlinear terms are 
> negligable and a gravitational wave is linear. This is easily quantized. 
> In 
> fact it is similar to the Hanbury-Brown and Twiss theory of the diphoton. 
> It is when the field becomes strong that general relativity becomes 
> nonlinear and runs into trouble with quantum mechanics.
>
> LC
>

 I assumed a quantum field theory of gravity must have a particle 
 associated with it, and that this particle is called the graviton. Gravity 
 is a fictitious force. So what would the role of the graviton be, if not 
 to 
 produce some force? If you detect gravitational waves, don't they consist 
 of gravitons if a quantum theory of gravity exists, analogous to photons 
 in 
 EM waves? AG

>>>
>>> Before you can present yourself as deeply knowledgeable of GR, you 
>>> should be able to give a coherent account how presumably *isolated* 
>>> bodies such as BH's, can gravitationally interact with what's exterior to 
>>> them. If gravitons can't do that in the context of a quantum theory of 
>>> gravity, what can?  AG
>>>
>>
>> It is the delay or tortoise coordinate basis for an external observer.
>>
>
> This is a tough subject to wrap one's head around. Wiki has a decent 
> article on it. There's an objective gravitational effect of a BH beyond its 
> event horizon. Are you claiming that the effect is only supported by theory 
> by a particular choice of coordinate system for an external observer? AG 
>
>>
>> LC 
>>
>

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Re: Principle of Equivalence



On Friday, July 17, 2020 at 11:54:20 AM UTC-6, Lawrence Crowell wrote:
>
> On Friday, July 17, 2020 at 11:43:48 AM UTC-5 agrays...@gmail.com wrote:
>
>>
>>
>> On Friday, July 17, 2020 at 5:34:17 AM UTC-6, Alan Grayson wrote:
>>>
>>>
>>>
>>> On Friday, July 17, 2020 at 4:48:51 AM UTC-6, Lawrence Crowell wrote:

 On Friday, July 17, 2020 at 5:01:41 AM UTC-5 agrays...@gmail.com wrote:

>
>
> On Thursday, July 16, 2020 at 7:50:07 PM UTC-6, Alan Grayson wrote:
>>
>>
>>
>> On Thursday, July 16, 2020 at 5:08:57 PM UTC-6, Lawrence Crowell 
>> wrote:
>>>
>>> Gravitons do not escape from a BH, any more than can light. However, 
>>> from the perspective of an outside observer all matter than went into a 
>>> BH 
>>> is on the surface above the event horizon, called the stretched 
>>> horizon. 
>>>
>>> LC
>>>
>>
>> Gravitons might not exist (and hence quantum gravity can't exist)  
>> But whatever the case, how can BH's interact gravitationally with 
>> objects 
>> beyond its event horizon? You say this doesn't happen. I don't 
>> understand 
>> your argument. AG 
>>
>
 That you are saying this illustrates you do not understand general 
 relativity.
  

>
> I may have identified the thousand pound gorilla in the room; the 
> hypothetical force carrying particle of the quantum gravitating field, 
> the 
> graviton, which for BH's doesn't exert any force! AG 
>

 I have no idea why you are saying this. Gravitation is not a force in 
 the usual sense and so the graviton does not produce a force in the 
 standard meaning. For the weak field limit the nonlinear terms are 
 negligable and a gravitational wave is linear. This is easily quantized. 
 In 
 fact it is similar to the Hanbury-Brown and Twiss theory of the diphoton. 
 It is when the field becomes strong that general relativity becomes 
 nonlinear and runs into trouble with quantum mechanics.

 LC

>>>
>>> I assumed a quantum field theory of gravity must have a particle 
>>> associated with it, and that this particle is called the graviton. Gravity 
>>> is a fictitious force. So what would the role of the graviton be, if not to 
>>> produce some force? If you detect gravitational waves, don't they consist 
>>> of gravitons if a quantum theory of gravity exists, analogous to photons in 
>>> EM waves? AG
>>>
>>
>> Before you can present yourself as deeply knowledgeable of GR, you should 
>> be able to give a coherent account how presumably *isolated* bodies such 
>> as BH's, can gravitationally interact with what's exterior to them. If 
>> gravitons can't do that in the context of a quantum theory of gravity, what 
>> can?  AG
>>
>
> It is the delay or tortoise coordinate basis for an external observer.
>

This is a tough subject to wrap one's head around. Wiki has a decent 
article on it. There's an objective gravitational effect of a BH beyond its 
event horizon. Are you claiming that the effect is only supported by theory 
by a particular choice of coordinate system for an external observer? AG 

>
> LC 
>

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Re: Principle of Equivalence

2020-07-17 Thread Lawrence Crowell

On Friday, July 17, 2020 at 11:43:48 AM UTC-5 agrays...@gmail.com wrote:

>
>
> On Friday, July 17, 2020 at 5:34:17 AM UTC-6, Alan Grayson wrote:
>>
>>
>>
>> On Friday, July 17, 2020 at 4:48:51 AM UTC-6, Lawrence Crowell wrote:
>>>
>>> On Friday, July 17, 2020 at 5:01:41 AM UTC-5 agrays...@gmail.com wrote:
>>>


 On Thursday, July 16, 2020 at 7:50:07 PM UTC-6, Alan Grayson wrote:
>
>
>
> On Thursday, July 16, 2020 at 5:08:57 PM UTC-6, Lawrence Crowell wrote:
>>
>> Gravitons do not escape from a BH, any more than can light. However, 
>> from the perspective of an outside observer all matter than went into a 
>> BH 
>> is on the surface above the event horizon, called the stretched horizon. 
>>
>> LC
>>
>
> Gravitons might not exist (and hence quantum gravity can't exist)  But 
> whatever the case, how can BH's interact gravitationally with objects 
> beyond its event horizon? You say this doesn't happen. I don't understand 
> your argument. AG 
>

>>> That you are saying this illustrates you do not understand general 
>>> relativity.
>>>  
>>>

 I may have identified the thousand pound gorilla in the room; the 
 hypothetical force carrying particle of the quantum gravitating field, the 
 graviton, which for BH's doesn't exert any force! AG 

>>>
>>> I have no idea why you are saying this. Gravitation is not a force in 
>>> the usual sense and so the graviton does not produce a force in the 
>>> standard meaning. For the weak field limit the nonlinear terms are 
>>> negligable and a gravitational wave is linear. This is easily quantized. In 
>>> fact it is similar to the Hanbury-Brown and Twiss theory of the diphoton. 
>>> It is when the field becomes strong that general relativity becomes 
>>> nonlinear and runs into trouble with quantum mechanics.
>>>
>>> LC
>>>
>>
>> I assumed a quantum field theory of gravity must have a particle 
>> associated with it, and that this particle is called the graviton. Gravity 
>> is a fictitious force. So what would the role of the graviton be, if not to 
>> produce some force? If you detect gravitational waves, don't they consist 
>> of gravitons if a quantum theory of gravity exists, analogous to photons in 
>> EM waves? AG
>>
>
> Before you can present yourself as deeply knowledgeable of GR, you should 
> be able to give a coherent account how presumably *isolated* bodies such 
> as BH's, can gravitationally interact with what's exterior to them. If 
> gravitons can't do that in the context of a quantum theory of gravity, what 
> can?  AG
>

It is the delay or tortoise coordinate basis for an external observer.

LC 

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Re: Principle of Equivalence



On Friday, July 17, 2020 at 5:34:17 AM UTC-6, Alan Grayson wrote:
>
>
>
> On Friday, July 17, 2020 at 4:48:51 AM UTC-6, Lawrence Crowell wrote:
>>
>> On Friday, July 17, 2020 at 5:01:41 AM UTC-5 agrays...@gmail.com wrote:
>>
>>>
>>>
>>> On Thursday, July 16, 2020 at 7:50:07 PM UTC-6, Alan Grayson wrote:



 On Thursday, July 16, 2020 at 5:08:57 PM UTC-6, Lawrence Crowell wrote:
>
> Gravitons do not escape from a BH, any more than can light. However, 
> from the perspective of an outside observer all matter than went into a 
> BH 
> is on the surface above the event horizon, called the stretched horizon. 
>
> LC
>

 Gravitons might not exist (and hence quantum gravity can't exist)  But 
 whatever the case, how can BH's interact gravitationally with objects 
 beyond its event horizon? You say this doesn't happen. I don't understand 
 your argument. AG 

>>>
>> That you are saying this illustrates you do not understand general 
>> relativity.
>>  
>>
>>>
>>> I may have identified the thousand pound gorilla in the room; the 
>>> hypothetical force carrying particle of the quantum gravitating field, the 
>>> graviton, which for BH's doesn't exert any force! AG 
>>>
>>
>> I have no idea why you are saying this. Gravitation is not a force in the 
>> usual sense and so the graviton does not produce a force in the standard 
>> meaning. For the weak field limit the nonlinear terms are negligable and a 
>> gravitational wave is linear. This is easily quantized. In fact it is 
>> similar to the Hanbury-Brown and Twiss theory of the diphoton. It is when 
>> the field becomes strong that general relativity becomes nonlinear and runs 
>> into trouble with quantum mechanics.
>>
>> LC
>>
>
> I assumed a quantum field theory of gravity must have a particle 
> associated with it, and that this particle is called the graviton. Gravity 
> is a fictitious force. So what would the role of the graviton be, if not to 
> produce some force? If you detect gravitational waves, don't they consist 
> of gravitons if a quantum theory of gravity exists, analogous to photons in 
> EM waves? AG
>

Before you can present yourself as deeply knowledgeable of GR, you should 
be able to give a coherent account how presumably *isolated* bodies such as 
BH's, can gravitationally interact with what's exterior to them. If 
gravitons can't do that in the context of a quantum theory of gravity, what 
can?  AG

-- 
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Re: Principle of Equivalence



On Friday, July 17, 2020 at 4:48:51 AM UTC-6, Lawrence Crowell wrote:
>
> On Friday, July 17, 2020 at 5:01:41 AM UTC-5 agrays...@gmail.com wrote:
>
>>
>>
>> On Thursday, July 16, 2020 at 7:50:07 PM UTC-6, Alan Grayson wrote:
>>>
>>>
>>>
>>> On Thursday, July 16, 2020 at 5:08:57 PM UTC-6, Lawrence Crowell wrote:

 Gravitons do not escape from a BH, any more than can light. However, 
 from the perspective of an outside observer all matter than went into a BH 
 is on the surface above the event horizon, called the stretched horizon. 

 LC

>>>
>>> Gravitons might not exist (and hence quantum gravity can't exist)  But 
>>> whatever the case, how can BH's interact gravitationally with objects 
>>> beyond its event horizon? You say this doesn't happen. I don't understand 
>>> your argument. AG 
>>>
>>
> That you are saying this illustrates you do not understand general 
> relativity.
>  
>
>>
>> I may have identified the thousand pound gorilla in the room; the 
>> hypothetical force carrying particle of the quantum gravitating field, the 
>> graviton, which for BH's doesn't exert any force! AG 
>>
>
> I have no idea why you are saying this. Gravitation is not a force in the 
> usual sense and so the graviton does not produce a force in the standard 
> meaning. For the weak field limit the nonlinear terms are negligable and a 
> gravitational wave is linear. This is easily quantized. In fact it is 
> similar to the Hanbury-Brown and Twiss theory of the diphoton. It is when 
> the field becomes strong that general relativity becomes nonlinear and runs 
> into trouble with quantum mechanics.
>
> LC
>

I assumed a quantum field theory of gravity must have a particle associated 
with it, and that this particle is called the graviton. Gravity is a 
fictitious force. So what would the role of the graviton be, if not to 
produce some force? If you detect gravitational waves, don't they consist 
of gravitons if a quantum theory of gravity exists, analogous to photons in 
EM waves? AG

-- 
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Re: Principle of Equivalence

2020-07-17 Thread Lawrence Crowell

On Friday, July 17, 2020 at 5:01:41 AM UTC-5 agrays...@gmail.com wrote:

>
>
> On Thursday, July 16, 2020 at 7:50:07 PM UTC-6, Alan Grayson wrote:
>>
>>
>>
>> On Thursday, July 16, 2020 at 5:08:57 PM UTC-6, Lawrence Crowell wrote:
>>>
>>> Gravitons do not escape from a BH, any more than can light. However, 
>>> from the perspective of an outside observer all matter than went into a BH 
>>> is on the surface above the event horizon, called the stretched horizon. 
>>>
>>> LC
>>>
>>
>> Gravitons might not exist (and hence quantum gravity can't exist)  But 
>> whatever the case, how can BH's interact gravitationally with objects 
>> beyond its event horizon? You say this doesn't happen. I don't understand 
>> your argument. AG 
>>
>
That you are saying this illustrates you do not understand general 
relativity.
 

>
> I may have identified the thousand pound gorilla in the room; the 
> hypothetical force carrying particle of the quantum gravitating field, the 
> graviton, which for BH's doesn't exert any force! AG 
>

I have no idea why you are saying this. Gravitation is not a force in the 
usual sense and so the graviton does not produce a force in the standard 
meaning. For the weak field limit the nonlinear terms are negligable and a 
gravitational wave is linear. This is easily quantized. In fact it is 
similar to the Hanbury-Brown and Twiss theory of the diphoton. It is when 
the field becomes strong that general relativity becomes nonlinear and runs 
into trouble with quantum mechanics.

LC

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Re: Principle of Equivalence



On Thursday, July 16, 2020 at 7:50:07 PM UTC-6, Alan Grayson wrote:
>
>
>
> On Thursday, July 16, 2020 at 5:08:57 PM UTC-6, Lawrence Crowell wrote:
>>
>> Gravitons do not escape from a BH, any more than can light. However, from 
>> the perspective of an outside observer all matter than went into a BH is on 
>> the surface above the event horizon, called the stretched horizon. 
>>
>> LC
>>
>
> Gravitons might not exist (and hence quantum gravity can't exist)  But 
> whatever the case, how can BH's interact gravitationally with objects 
> beyond its event horizon? You say this doesn't happen. I don't understand 
> your argument. AG 
>

I may have identified the thousand pound gorilla in the room; the 
hypothetical force carrying particle of the quantum gravitating field, the 
graviton, which for BH's doesn't exert any force! AG 

>
>>
>> On Thursday, July 16, 2020 at 9:08:11 AM UTC-5 agrays...@gmail.com wrote:
>>
>>>
>>>
>>> On Tuesday, July 14, 2020 at 10:59:54 PM UTC-6, Alan Grayson wrote:



 On Tuesday, July 14, 2020 at 4:45:25 PM UTC-6, Lawrence Crowell wrote:
>
>
>
> On Tuesday, July 14, 2020 at 2:25:39 PM UTC-5, Alan Grayson wrote:
>>
>>
>>
>> On Tuesday, July 14, 2020 at 9:43:11 AM UTC-6, Lawrence Crowell wrote:
>>>
>>> On Tuesday, July 14, 2020 at 5:55:52 AM UTC-5, Alan Grayson wrote:



 On Tuesday, July 14, 2020 at 4:34:00 AM UTC-6, Lawrence Crowell 
 wrote:
>
> On Monday, July 13, 2020 at 6:30:46 PM UTC-5, Alan Grayson wrote:
>>
>>
>>
>> On Monday, July 13, 2020 at 5:19:30 PM UTC-6, Lawrence Crowell 
>> wrote:
>>>
>>>
>>>
>> About the EP; I merely stated that it demonstrates that 
>> acceleration is locally indistinguishable from gravity, and then I 
>> stated 
>> what "locally" means. This is what Wiki and other sources say.  Yet 
>> you say 
>> I am confused. How so? About masses of BH's, I watch documentaries 
>> which 
>> feature astrophysicists offering their opinions, and they 
>> *uniformly* claim that BH's have mass. How could it be otherwise 
>> if they're remnants of massive collapsed stars? Not one makes 
>> Brent's 
>> claim, that they're just geometric manifestations.  AG
>>
>
> Black hole mass is a pure spacetime physics. There is no material 
> stuff anyone can get their hands on. With the tortoise coordinate the 
> distant observer might say the matter-fields that made of a black 
> hole 
> exist, but if one tried to reach them they always recede away. Black 
> holes 
> do not have mass in a standard sense, though they have an ADM mass 
> defined 
> by the curvature of spacetime.
>

 Generally, what resides inside a BH interacts gravitationally with 
 what's exterior and is the remnant of a Type 1A supernova. It's 
 unreachable, but has some correspondence with normal mass, which is 
 why its 
 mass can be estimated by its exterior effects, say for the one 
 residing at 
 the core of the Milky Way. I don't know how their masses are estimated 
 when 
 they are cores of distant galaxies. AG 

>>>
>>> The interior does not interact with the exterior. The event horizon 
>>> prevents that. 
>>>
>>
>> Then how can a BH interact gravitationally with objects external to 
>> the event horizon, or do you deny that? AG
>>
>
> The black hole does not interact with material outside, the material 
> outside interacts with the black hole. A black hole is a causality sink; 
> causal propagation is into the black hole. Only stochastic quantum events 
> propagate out. 
>
> LC
>

 I am not sure I understand or agree. Space-time is strongly curved near 
 a BH. Are you claiming this curvature is not caused by the BH? In any 
 event, doesn't this put a nail in the coffin of quantum gravity? IIUC, the 
 force carrying particle in a quantum gravity theory is the graviton. If 
 nothing can get out of a BH, this would apply to the graviton. Seems like 
 a 
 problem for any quantum gravity theory. AG 

>>>
>>> Let me put the question another way; if gravitons exist, could they 
>>> escape a BH? If not, does this adversely effect the existence of a quantum 
>>> theory of gravity? TIA, AG 
>>>
  
>
>>  
>>
>>> From the perspective of anyone in the exterior the interior of a 
>>> black hole is nothing more than a theoretical abstraction. It only 
>>> exists 
>>> as a counter factual situation, where instead of remaining outside an 
>>> observer enters the BH/ 
>>>
>>> LC
>>>
>>

-- 
You received this message

Re: Principle of Equivalence

2020-07-16 Thread Alan Grayson



On Thursday, July 16, 2020 at 5:08:57 PM UTC-6, Lawrence Crowell wrote:
>
> Gravitons do not escape from a BH, any more than can light. However, from 
> the perspective of an outside observer all matter than went into a BH is on 
> the surface above the event horizon, called the stretched horizon. 
>
> LC
>

Gravitons might not exist (and hence quantum gravity can't exist)  But 
whatever the case, how can BH's interact gravitationally with objects 
beyond its event horizon? You say this doesn't happen. I don't understand 
your argument. AG 

>
>
> On Thursday, July 16, 2020 at 9:08:11 AM UTC-5 agrays...@gmail.com wrote:
>
>>
>>
>> On Tuesday, July 14, 2020 at 10:59:54 PM UTC-6, Alan Grayson wrote:
>>>
>>>
>>>
>>> On Tuesday, July 14, 2020 at 4:45:25 PM UTC-6, Lawrence Crowell wrote:



 On Tuesday, July 14, 2020 at 2:25:39 PM UTC-5, Alan Grayson wrote:
>
>
>
> On Tuesday, July 14, 2020 at 9:43:11 AM UTC-6, Lawrence Crowell wrote:
>>
>> On Tuesday, July 14, 2020 at 5:55:52 AM UTC-5, Alan Grayson wrote:
>>>
>>>
>>>
>>> On Tuesday, July 14, 2020 at 4:34:00 AM UTC-6, Lawrence Crowell 
>>> wrote:

 On Monday, July 13, 2020 at 6:30:46 PM UTC-5, Alan Grayson wrote:
>
>
>
> On Monday, July 13, 2020 at 5:19:30 PM UTC-6, Lawrence Crowell 
> wrote:
>>
>>
>>
> About the EP; I merely stated that it demonstrates that 
> acceleration is locally indistinguishable from gravity, and then I 
> stated 
> what "locally" means. This is what Wiki and other sources say.  Yet 
> you say 
> I am confused. How so? About masses of BH's, I watch documentaries 
> which 
> feature astrophysicists offering their opinions, and they 
> *uniformly* claim that BH's have mass. How could it be otherwise 
> if they're remnants of massive collapsed stars? Not one makes Brent's 
> claim, that they're just geometric manifestations.  AG
>

 Black hole mass is a pure spacetime physics. There is no material 
 stuff anyone can get their hands on. With the tortoise coordinate the 
 distant observer might say the matter-fields that made of a black hole 
 exist, but if one tried to reach them they always recede away. Black 
 holes 
 do not have mass in a standard sense, though they have an ADM mass 
 defined 
 by the curvature of spacetime.

>>>
>>> Generally, what resides inside a BH interacts gravitationally with 
>>> what's exterior and is the remnant of a Type 1A supernova. It's 
>>> unreachable, but has some correspondence with normal mass, which is why 
>>> its 
>>> mass can be estimated by its exterior effects, say for the one residing 
>>> at 
>>> the core of the Milky Way. I don't know how their masses are estimated 
>>> when 
>>> they are cores of distant galaxies. AG 
>>>
>>
>> The interior does not interact with the exterior. The event horizon 
>> prevents that. 
>>
>
> Then how can a BH interact gravitationally with objects external to 
> the event horizon, or do you deny that? AG
>

 The black hole does not interact with material outside, the material 
 outside interacts with the black hole. A black hole is a causality sink; 
 causal propagation is into the black hole. Only stochastic quantum events 
 propagate out. 

 LC

>>>
>>> I am not sure I understand or agree. Space-time is strongly curved near 
>>> a BH. Are you claiming this curvature is not caused by the BH? In any 
>>> event, doesn't this put a nail in the coffin of quantum gravity? IIUC, the 
>>> force carrying particle in a quantum gravity theory is the graviton. If 
>>> nothing can get out of a BH, this would apply to the graviton. Seems like a 
>>> problem for any quantum gravity theory. AG 
>>>
>>
>> Let me put the question another way; if gravitons exist, could they 
>> escape a BH? If not, does this adversely effect the existence of a quantum 
>> theory of gravity? TIA, AG 
>>
>>>  

>  
>
>> From the perspective of anyone in the exterior the interior of a 
>> black hole is nothing more than a theoretical abstraction. It only 
>> exists 
>> as a counter factual situation, where instead of remaining outside an 
>> observer enters the BH/ 
>>
>> LC
>>
>

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Re: Principle of Equivalence

2020-07-16 Thread 'Brent Meeker' via Everything List

I wonder about the use of cicumlocutions like "from the perspective of 
an outside observer".  In special relativity it it is often said that a 
moving object will looked shortened along the direction of motion.  But 
as Terrell pointed out that's not at all how they look.  It is more 
accurate to say that /measuring/ a moving a object will show that it is 
shortened along the direction of motion; the difference being that the 
measurement corrects for the fact that you want the difference in 
arrival time of photons that left the ends of the object at the same 
time (an ill defined concept), instead of the image formed by photons 
that arrived at the same time.  But then I think, why not correct for 
the Lorentz contraction too in the measurement and arrive at what we 
might call "the proper length".  That's just as "measured" as either of 
the other two.


By the same reasoning, you're really saying the visual impression of a 
distant observer is that infalling stuff appears to be on the surface of 
the event horizon. Which is because it takes forever for photons to 
reach him.  But why should he be so naive.  He knows what he's seeing is 
arbitrarily far in his past; so what he should be said to "measure" or 
"calculate" is that the stuff has already been annihilated at the 
"singularity" in his reference frame.


Brent

On 7/16/2020 4:08 PM, Lawrence Crowell wrote:
Gravitons do not escape from a BH, any more than can light. However, 
from the perspective of an outside observer all matter than went into 
a BH is on the surface above the event horizon, called the stretched 
horizon.


LC

On Thursday, July 16, 2020 at 9:08:11 AM UTC-5 agrays...@gmail.com wrote:



On Tuesday, July 14, 2020 at 10:59:54 PM UTC-6, Alan Grayson wrote:



On Tuesday, July 14, 2020 at 4:45:25 PM UTC-6, Lawrence
Crowell wrote:



On Tuesday, July 14, 2020 at 2:25:39 PM UTC-5, Alan
Grayson wrote:



On Tuesday, July 14, 2020 at 9:43:11 AM UTC-6,
Lawrence Crowell wrote:

On Tuesday, July 14, 2020 at 5:55:52 AM UTC-5,
Alan Grayson wrote:



On Tuesday, July 14, 2020 at 4:34:00 AM UTC-6,
Lawrence Crowell wrote:

On Monday, July 13, 2020 at 6:30:46 PM
UTC-5, Alan Grayson wrote:



On Monday, July 13, 2020 at 5:19:30 PM
UTC-6, Lawrence Crowell wrote:



About the EP; I merely stated that it
demonstrates that acceleration is
locally indistinguishable from
gravity, and then I stated what
"locally" means. This is what Wiki and
other sources say.  Yet you say I am
confused. How so? About masses of
BH's, I watch documentaries which
feature astrophysicists offering their
opinions, and they *uniformly* claim
that BH's have mass. How could it be
otherwise if they're remnants of
massive collapsed stars? Not one makes
Brent's claim, that they're just
geometric manifestations.  AG


Black hole mass is a pure spacetime
physics. There is no material stuff anyone
can get their hands on. With the tortoise
coordinate the distant observer might say
the matter-fields that made of a black
hole exist, but if one tried to reach them
they always recede away. Black holes do
not have mass in a standard sense, though
they have an ADM mass defined by the
curvature of spacetime.


Generally, what resides inside a BH interacts
gravitationally with what's exterior and is
the remnant of a Type 1A supernova. It's
unreachable, but has some correspondence with
normal mass, which is why its mass can be
estimated by its exterior effects, say for the
one residing at the core of the Milky Way. I
don't know how their masses are estimated when
they are cores of distant galaxies. AG


The interior does not interact with the exterior.
The event horizon prevents that.


Then how can

Re: Principle of Equivalence

2020-07-16 Thread Lawrence Crowell

Gravitons do not escape from a BH, any more than can light. However, from 
the perspective of an outside observer all matter than went into a BH is on 
the surface above the event horizon, called the stretched horizon. 

LC

On Thursday, July 16, 2020 at 9:08:11 AM UTC-5 agrays...@gmail.com wrote:

>
>
> On Tuesday, July 14, 2020 at 10:59:54 PM UTC-6, Alan Grayson wrote:
>>
>>
>>
>> On Tuesday, July 14, 2020 at 4:45:25 PM UTC-6, Lawrence Crowell wrote:
>>>
>>>
>>>
>>> On Tuesday, July 14, 2020 at 2:25:39 PM UTC-5, Alan Grayson wrote:



 On Tuesday, July 14, 2020 at 9:43:11 AM UTC-6, Lawrence Crowell wrote:
>
> On Tuesday, July 14, 2020 at 5:55:52 AM UTC-5, Alan Grayson wrote:
>>
>>
>>
>> On Tuesday, July 14, 2020 at 4:34:00 AM UTC-6, Lawrence Crowell wrote:
>>>
>>> On Monday, July 13, 2020 at 6:30:46 PM UTC-5, Alan Grayson wrote:



 On Monday, July 13, 2020 at 5:19:30 PM UTC-6, Lawrence Crowell 
 wrote:
>
>
>
 About the EP; I merely stated that it demonstrates that 
 acceleration is locally indistinguishable from gravity, and then I 
 stated 
 what "locally" means. This is what Wiki and other sources say.  Yet 
 you say 
 I am confused. How so? About masses of BH's, I watch documentaries 
 which 
 feature astrophysicists offering their opinions, and they 
 *uniformly* claim that BH's have mass. How could it be otherwise 
 if they're remnants of massive collapsed stars? Not one makes Brent's 
 claim, that they're just geometric manifestations.  AG

>>>
>>> Black hole mass is a pure spacetime physics. There is no material 
>>> stuff anyone can get their hands on. With the tortoise coordinate the 
>>> distant observer might say the matter-fields that made of a black hole 
>>> exist, but if one tried to reach them they always recede away. Black 
>>> holes 
>>> do not have mass in a standard sense, though they have an ADM mass 
>>> defined 
>>> by the curvature of spacetime.
>>>
>>
>> Generally, what resides inside a BH interacts gravitationally with 
>> what's exterior and is the remnant of a Type 1A supernova. It's 
>> unreachable, but has some correspondence with normal mass, which is why 
>> its 
>> mass can be estimated by its exterior effects, say for the one residing 
>> at 
>> the core of the Milky Way. I don't know how their masses are estimated 
>> when 
>> they are cores of distant galaxies. AG 
>>
>
> The interior does not interact with the exterior. The event horizon 
> prevents that. 
>

 Then how can a BH interact gravitationally with objects external to the 
 event horizon, or do you deny that? AG

>>>
>>> The black hole does not interact with material outside, the material 
>>> outside interacts with the black hole. A black hole is a causality sink; 
>>> causal propagation is into the black hole. Only stochastic quantum events 
>>> propagate out. 
>>>
>>> LC
>>>
>>
>> I am not sure I understand or agree. Space-time is strongly curved near a 
>> BH. Are you claiming this curvature is not caused by the BH? In any event, 
>> doesn't this put a nail in the coffin of quantum gravity? IIUC, the force 
>> carrying particle in a quantum gravity theory is the graviton. If nothing 
>> can get out of a BH, this would apply to the graviton. Seems like a problem 
>> for any quantum gravity theory. AG 
>>
>
> Let me put the question another way; if gravitons exist, could they escape 
> a BH? If not, does this adversely effect the existence of a quantum theory 
> of gravity? TIA, AG 
>
>>  
>>>
  

> From the perspective of anyone in the exterior the interior of a black 
> hole is nothing more than a theoretical abstraction. It only exists as a 
> counter factual situation, where instead of remaining outside an observer 
> enters the BH/ 
>
> LC
>


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Re: Principle of Equivalence

2020-07-16 Thread Alan Grayson



On Tuesday, July 14, 2020 at 10:59:54 PM UTC-6, Alan Grayson wrote:
>
>
>
> On Tuesday, July 14, 2020 at 4:45:25 PM UTC-6, Lawrence Crowell wrote:
>>
>>
>>
>> On Tuesday, July 14, 2020 at 2:25:39 PM UTC-5, Alan Grayson wrote:
>>>
>>>
>>>
>>> On Tuesday, July 14, 2020 at 9:43:11 AM UTC-6, Lawrence Crowell wrote:

 On Tuesday, July 14, 2020 at 5:55:52 AM UTC-5, Alan Grayson wrote:
>
>
>
> On Tuesday, July 14, 2020 at 4:34:00 AM UTC-6, Lawrence Crowell wrote:
>>
>> On Monday, July 13, 2020 at 6:30:46 PM UTC-5, Alan Grayson wrote:
>>>
>>>
>>>
>>> On Monday, July 13, 2020 at 5:19:30 PM UTC-6, Lawrence Crowell wrote:



>>> About the EP; I merely stated that it demonstrates that acceleration 
>>> is locally indistinguishable from gravity, and then I stated what 
>>> "locally" 
>>> means. This is what Wiki and other sources say.  Yet you say I am 
>>> confused. 
>>> How so? About masses of BH's, I watch documentaries which feature 
>>> astrophysicists offering their opinions, and they *uniformly* claim 
>>> that BH's have mass. How could it be otherwise if they're remnants of 
>>> massive collapsed stars? Not one makes Brent's claim, that they're just 
>>> geometric manifestations.  AG
>>>
>>
>> Black hole mass is a pure spacetime physics. There is no material 
>> stuff anyone can get their hands on. With the tortoise coordinate the 
>> distant observer might say the matter-fields that made of a black hole 
>> exist, but if one tried to reach them they always recede away. Black 
>> holes 
>> do not have mass in a standard sense, though they have an ADM mass 
>> defined 
>> by the curvature of spacetime.
>>
>
> Generally, what resides inside a BH interacts gravitationally with 
> what's exterior and is the remnant of a Type 1A supernova. It's 
> unreachable, but has some correspondence with normal mass, which is why 
> its 
> mass can be estimated by its exterior effects, say for the one residing 
> at 
> the core of the Milky Way. I don't know how their masses are estimated 
> when 
> they are cores of distant galaxies. AG 
>

 The interior does not interact with the exterior. The event horizon 
 prevents that. 

>>>
>>> Then how can a BH interact gravitationally with objects external to the 
>>> event horizon, or do you deny that? AG
>>>
>>
>> The black hole does not interact with material outside, the material 
>> outside interacts with the black hole. A black hole is a causality sink; 
>> causal propagation is into the black hole. Only stochastic quantum events 
>> propagate out. 
>>
>> LC
>>
>
> I am not sure I understand or agree. Space-time is strongly curved near a 
> BH. Are you claiming this curvature is not caused by the BH? In any event, 
> doesn't this put a nail in the coffin of quantum gravity? IIUC, the force 
> carrying particle in a quantum gravity theory is the graviton. If nothing 
> can get out of a BH, this would apply to the graviton. Seems like a problem 
> for any quantum gravity theory. AG 
>

Let me put the question another way; if gravitons exist, could they escape 
a BH? If not, does this adversely effect the existence of a quantum theory 
of gravity? TIA, AG 

>  
>>
>>>  
>>>
 From the perspective of anyone in the exterior the interior of a black 
 hole is nothing more than a theoretical abstraction. It only exists as a 
 counter factual situation, where instead of remaining outside an observer 
 enters the BH/ 

 LC

>>>

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Re: Principle of Equivalence

2020-07-15 Thread Philip Thrift



> Can't fermions be considered "matter"? AG


"Thus, matter can be defined as everything composed of elementary fermions."
https://en.wikipedia.org/wiki/Matter

@philipthrift 


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Re: Principle of Equivalence



On Tuesday, July 14, 2020 at 4:45:25 PM UTC-6, Lawrence Crowell wrote:
>
>
>
> On Tuesday, July 14, 2020 at 2:25:39 PM UTC-5, Alan Grayson wrote:
>>
>>
>>
>> On Tuesday, July 14, 2020 at 9:43:11 AM UTC-6, Lawrence Crowell wrote:
>>>
>>> On Tuesday, July 14, 2020 at 5:55:52 AM UTC-5, Alan Grayson wrote:



 On Tuesday, July 14, 2020 at 4:34:00 AM UTC-6, Lawrence Crowell wrote:
>
> On Monday, July 13, 2020 at 6:30:46 PM UTC-5, Alan Grayson wrote:
>>
>>
>>
>> On Monday, July 13, 2020 at 5:19:30 PM UTC-6, Lawrence Crowell wrote:
>>>
>>>
>>>
>> About the EP; I merely stated that it demonstrates that acceleration 
>> is locally indistinguishable from gravity, and then I stated what 
>> "locally" 
>> means. This is what Wiki and other sources say.  Yet you say I am 
>> confused. 
>> How so? About masses of BH's, I watch documentaries which feature 
>> astrophysicists offering their opinions, and they *uniformly* claim 
>> that BH's have mass. How could it be otherwise if they're remnants of 
>> massive collapsed stars? Not one makes Brent's claim, that they're just 
>> geometric manifestations.  AG
>>
>
> Black hole mass is a pure spacetime physics. There is no material 
> stuff anyone can get their hands on. With the tortoise coordinate the 
> distant observer might say the matter-fields that made of a black hole 
> exist, but if one tried to reach them they always recede away. Black 
> holes 
> do not have mass in a standard sense, though they have an ADM mass 
> defined 
> by the curvature of spacetime.
>

 Generally, what resides inside a BH interacts gravitationally with 
 what's exterior and is the remnant of a Type 1A supernova. It's 
 unreachable, but has some correspondence with normal mass, which is why 
 its 
 mass can be estimated by its exterior effects, say for the one residing at 
 the core of the Milky Way. I don't know how their masses are estimated 
 when 
 they are cores of distant galaxies. AG 

>>>
>>> The interior does not interact with the exterior. The event horizon 
>>> prevents that. 
>>>
>>
>> Then how can a BH interact gravitationally with objects external to the 
>> event horizon, or do you deny that? AG
>>
>
> The black hole does not interact with material outside, the material 
> outside interacts with the black hole. A black hole is a causality sink; 
> causal propagation is into the black hole. Only stochastic quantum events 
> propagate out. 
>
> LC
>

I am not sure I understand or agree. Space-time is strongly curved near a 
BH. Are you claiming this curvature is not caused by the BH? In any event, 
doesn't this put a nail in the coffin of quantum gravity? IIUC, the force 
carrying particle in a quantum gravity theory is the graviton. If nothing 
can get out of a BH, this would apply to the graviton. Seems like a problem 
for any quantum gravity theory. AG 

>  
>
>>  
>>
>>> From the perspective of anyone in the exterior the interior of a black 
>>> hole is nothing more than a theoretical abstraction. It only exists as a 
>>> counter factual situation, where instead of remaining outside an observer 
>>> enters the BH/ 
>>>
>>> LC
>>>
>>

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Re: Principle of Equivalence



On Tuesday, July 14, 2020 at 10:32:59 PM UTC-6, Alan Grayson wrote:
>
>
>
> On Tuesday, July 14, 2020 at 4:27:35 PM UTC-6, Brent wrote:
>>
>>
>>
>> On 7/14/2020 2:36 PM, Alan Grayson wrote:
>>
>>
>>
>> On Tuesday, July 14, 2020 at 2:50:12 PM UTC-6, Brent wrote: 
>>>
>>>
>>>
>>> On 7/14/2020 12:22 PM, Alan Grayson wrote:
>>>
>>>
>>>
>>> On Tuesday, July 14, 2020 at 11:31:42 AM UTC-6, Brent wrote: 



 On 7/14/2020 3:34 AM, Lawrence Crowell wrote:

 On Monday, July 13, 2020 at 6:30:46 PM UTC-5, Alan Grayson wrote: 
>
>
>
> On Monday, July 13, 2020 at 5:19:30 PM UTC-6, Lawrence Crowell wrote: 
>>
>> On Monday, July 13, 2020 at 4:42:24 PM UTC-5, Alan Grayson wrote: 
>>>
>>>
>>>
>>> On Monday, July 13, 2020 at 1:42:49 PM UTC-6, Alan Grayson wrote: 



 On Monday, July 13, 2020 at 11:57:50 AM UTC-6, Brent wrote: 
>
>
>
> On 7/12/2020 11:50 PM, Alan Grayson wrote:
>
> There can be because it's consistent with the equations.  A black 
>> hole doesn't include any matter.  General relativity is non-linear, 
>> that's 
>> why there can be non-flat cosmologies that contain no matter.  Of 
>> course 
>> there may be some different, better theory in which spacetime can't 
>> be 
>> curved without matter...but it seems unlikely since we have good 
>> evidence 
>> that gravitational waves exist.
>>
>> Brent
>>
>
> Yes, good evidence that gravitational waves exist, but as far I 
> know they're always associated with material interactions such as 
> collisions of black holes. In the case of EM waves, I'd be more 
> receptive 
> of your claim that they can exist independent of charges and/or 
> currents, 
> but as far as I know there's no evidence of that. AG 
>
>>
> But a collision of black holes does NOT involve matter.  Black 
> holes (as far as the theory goes) are purely geometric things, i.e. 
> made of 
> empty space.
>
> Brent
>

 How then does the BH at the center of our galaxy weigh in at 4 
 million solar masses? AG 

>>>
>>> It's measured by observing the rotation rates of stars near the 
>>> galactic core, and not so small by comparison with other BH's at the 
>>> center 
>>> of galaxies, called Super Massive BH's. AG 
>>>
>>
>> It is unfortunately apparent that you are pretty highly confused by 
>> some of this. You need to sit down and read a comprehensive book or text 
>> on 
>> GR and related subjects. It is not going to be possible to clear this up 
>> with dozens of email posts.
>>
>> LC 
>>
>
> About the EP; I merely stated that it demonstrates that acceleration 
> is locally indistinguishable from gravity, and then I stated what 
> "locally" 
> means. This is what Wiki and other sources say.  Yet you say I am 
> confused. 
> How so? About masses of BH's, I watch documentaries which feature 
> astrophysicists offering their opinions, and they *uniformly* claim 
> that BH's have mass. How could it be otherwise if they're remnants of 
> massive collapsed stars? Not one makes Brent's claim, that they're just 
> geometric manifestations.  AG
>

 I didn't say they lacked mass.  I said they lacked matter.  Thus 
 countering your assumption that gravity requires matter.

 Brent

>>>
>>> I could have said that gravity requires mass/energy. What's the 
>>> distinction between matter and mass? TIA, AG 
>>>
>>>
>>> Some things, e.g. black holes, have mass without matter (at least as far 
>>> as GR goes).
>>>
>>> Brent
>>>
>>
>> What's the distinction between matter and mass? AG
>>
>>
>> What's your problem.  Do  you just want to argument semantics.  I don't 
>> care if you want to call a black hole "matter", but nobody else does.  
>> Everybody else means localized packets of mass-energy in the form of 
>> fermions.
>>
>> Brent
>>
>
>
> Do I just want to argue semantics? No, of course not, But you seem to want 
> that. Otherwise, instead of trying to put me down, you could have just 
> assumed I meant MASS!  IIRC, at some point above I did refer to E=mc^2, 
> which equates MASS with energy. AG 
>

But if I wanted to argue semantics, I could win!  Can't fermions be 
considered "matter"? AG

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Re: Principle of Equivalence



On Tuesday, July 14, 2020 at 4:27:35 PM UTC-6, Brent wrote:
>
>
>
> On 7/14/2020 2:36 PM, Alan Grayson wrote:
>
>
>
> On Tuesday, July 14, 2020 at 2:50:12 PM UTC-6, Brent wrote: 
>>
>>
>>
>> On 7/14/2020 12:22 PM, Alan Grayson wrote:
>>
>>
>>
>> On Tuesday, July 14, 2020 at 11:31:42 AM UTC-6, Brent wrote: 
>>>
>>>
>>>
>>> On 7/14/2020 3:34 AM, Lawrence Crowell wrote:
>>>
>>> On Monday, July 13, 2020 at 6:30:46 PM UTC-5, Alan Grayson wrote: 



 On Monday, July 13, 2020 at 5:19:30 PM UTC-6, Lawrence Crowell wrote: 
>
> On Monday, July 13, 2020 at 4:42:24 PM UTC-5, Alan Grayson wrote: 
>>
>>
>>
>> On Monday, July 13, 2020 at 1:42:49 PM UTC-6, Alan Grayson wrote: 
>>>
>>>
>>>
>>> On Monday, July 13, 2020 at 11:57:50 AM UTC-6, Brent wrote: 



 On 7/12/2020 11:50 PM, Alan Grayson wrote:

 There can be because it's consistent with the equations.  A black 
> hole doesn't include any matter.  General relativity is non-linear, 
> that's 
> why there can be non-flat cosmologies that contain no matter.  Of 
> course 
> there may be some different, better theory in which spacetime can't 
> be 
> curved without matter...but it seems unlikely since we have good 
> evidence 
> that gravitational waves exist.
>
> Brent
>

 Yes, good evidence that gravitational waves exist, but as far I 
 know they're always associated with material interactions such as 
 collisions of black holes. In the case of EM waves, I'd be more 
 receptive 
 of your claim that they can exist independent of charges and/or 
 currents, 
 but as far as I know there's no evidence of that. AG 

>
 But a collision of black holes does NOT involve matter.  Black 
 holes (as far as the theory goes) are purely geometric things, i.e. 
 made of 
 empty space.

 Brent

>>>
>>> How then does the BH at the center of our galaxy weigh in at 4 
>>> million solar masses? AG 
>>>
>>
>> It's measured by observing the rotation rates of stars near the 
>> galactic core, and not so small by comparison with other BH's at the 
>> center 
>> of galaxies, called Super Massive BH's. AG 
>>
>
> It is unfortunately apparent that you are pretty highly confused by 
> some of this. You need to sit down and read a comprehensive book or text 
> on 
> GR and related subjects. It is not going to be possible to clear this up 
> with dozens of email posts.
>
> LC 
>

 About the EP; I merely stated that it demonstrates that acceleration is 
 locally indistinguishable from gravity, and then I stated what "locally" 
 means. This is what Wiki and other sources say.  Yet you say I am 
 confused. 
 How so? About masses of BH's, I watch documentaries which feature 
 astrophysicists offering their opinions, and they *uniformly* claim 
 that BH's have mass. How could it be otherwise if they're remnants of 
 massive collapsed stars? Not one makes Brent's claim, that they're just 
 geometric manifestations.  AG

>>>
>>> I didn't say they lacked mass.  I said they lacked matter.  Thus 
>>> countering your assumption that gravity requires matter.
>>>
>>> Brent
>>>
>>
>> I could have said that gravity requires mass/energy. What's the 
>> distinction between matter and mass? TIA, AG 
>>
>>
>> Some things, e.g. black holes, have mass without matter (at least as far 
>> as GR goes).
>>
>> Brent
>>
>
> What's the distinction between matter and mass? AG
>
>
> What's your problem.  Do  you just want to argument semantics.  I don't 
> care if you want to call a black hole "matter", but nobody else does.  
> Everybody else means localized packets of mass-energy in the form of 
> fermions.
>
> Brent
>


Do I just want to argue semantics? No, of course not, But you seem to want 
that. Otherwise, instead of trying to put me down, you could have just 
assumed I meant MASS!  IIRC, at some point above I did refer to E=mc^2, 
which equates MASS with energy. AG 

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Re: Principle of Equivalence

2020-07-14 Thread Lawrence Crowell



On Tuesday, July 14, 2020 at 2:25:39 PM UTC-5, Alan Grayson wrote:
>
>
>
> On Tuesday, July 14, 2020 at 9:43:11 AM UTC-6, Lawrence Crowell wrote:
>>
>> On Tuesday, July 14, 2020 at 5:55:52 AM UTC-5, Alan Grayson wrote:
>>>
>>>
>>>
>>> On Tuesday, July 14, 2020 at 4:34:00 AM UTC-6, Lawrence Crowell wrote:

 On Monday, July 13, 2020 at 6:30:46 PM UTC-5, Alan Grayson wrote:
>
>
>
> On Monday, July 13, 2020 at 5:19:30 PM UTC-6, Lawrence Crowell wrote:
>>
>>
>>
> About the EP; I merely stated that it demonstrates that acceleration 
> is locally indistinguishable from gravity, and then I stated what 
> "locally" 
> means. This is what Wiki and other sources say.  Yet you say I am 
> confused. 
> How so? About masses of BH's, I watch documentaries which feature 
> astrophysicists offering their opinions, and they *uniformly* claim 
> that BH's have mass. How could it be otherwise if they're remnants of 
> massive collapsed stars? Not one makes Brent's claim, that they're just 
> geometric manifestations.  AG
>

 Black hole mass is a pure spacetime physics. There is no material stuff 
 anyone can get their hands on. With the tortoise coordinate the distant 
 observer might say the matter-fields that made of a black hole exist, but 
 if one tried to reach them they always recede away. Black holes do not 
 have 
 mass in a standard sense, though they have an ADM mass defined by the 
 curvature of spacetime.

>>>
>>> Generally, what resides inside a BH interacts gravitationally with 
>>> what's exterior and is the remnant of a Type 1A supernova. It's 
>>> unreachable, but has some correspondence with normal mass, which is why its 
>>> mass can be estimated by its exterior effects, say for the one residing at 
>>> the core of the Milky Way. I don't know how their masses are estimated when 
>>> they are cores of distant galaxies. AG 
>>>
>>
>> The interior does not interact with the exterior. The event horizon 
>> prevents that. 
>>
>
> Then how can a BH interact gravitationally with objects external to the 
> event horizon, or do you deny that? AG
>

The black hole does not interact with material outside, the material 
outside interacts with the black hole. A black hole is a causality sink; 
causal propagation is into the black hole. Only stochastic quantum events 
propagate out. 

LC
 

>  
>
>> From the perspective of anyone in the exterior the interior of a black 
>> hole is nothing more than a theoretical abstraction. It only exists as a 
>> counter factual situation, where instead of remaining outside an observer 
>> enters the BH/ 
>>
>> LC
>>
>

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Re: Principle of Equivalence

2020-07-14 Thread 'Brent Meeker' via Everything List




On 7/14/2020 2:36 PM, Alan Grayson wrote:



On Tuesday, July 14, 2020 at 2:50:12 PM UTC-6, Brent wrote:



On 7/14/2020 12:22 PM, Alan Grayson wrote:



On Tuesday, July 14, 2020 at 11:31:42 AM UTC-6, Brent wrote:



On 7/14/2020 3:34 AM, Lawrence Crowell wrote:

On Monday, July 13, 2020 at 6:30:46 PM UTC-5, Alan Grayson
wrote:



On Monday, July 13, 2020 at 5:19:30 PM UTC-6, Lawrence
Crowell wrote:

On Monday, July 13, 2020 at 4:42:24 PM UTC-5, Alan
Grayson wrote:



On Monday, July 13, 2020 at 1:42:49 PM UTC-6,
Alan Grayson wrote:



On Monday, July 13, 2020 at 11:57:50 AM
UTC-6, Brent wrote:



On 7/12/2020 11:50 PM, Alan Grayson wrote:


There can be because it's
consistent with the equations.  A
black hole doesn't include any
matter.  General relativity is
non-linear, that's why there can be
non-flat cosmologies that contain
no matter.  Of course there may be
some different, better theory in
which spacetime can't be curved
without matter...but it seems
unlikely since we have good
evidence that gravitational waves
exist.

Brent


Yes, good evidence that gravitational
waves exist, but as far I know they're
always associated with material
interactions such as collisions of
black holes. In the case of EM waves,
I'd be more receptive of your claim
that they can exist independent of
charges and/or currents, but as far as
I know there's no evidence of that. AG



But a collision of black holes does NOT
involve matter.  Black holes (as far as
the theory goes) are purely geometric
things, i.e. made of empty space.

Brent


How then does the BH at the center of our
galaxy weigh in at 4 million solar masses? AG


It's measured by observing the rotation rates of
stars near the galactic core, and not so small
by comparison with other BH's at the center of
galaxies, called Super Massive BH's. AG


It is unfortunately apparent that you are pretty
highly confused by some of this. You need to sit
down and read a comprehensive book or text on GR and
related subjects. It is not going to be possible to
clear this up with dozens of email posts.

LC


About the EP; I merely stated that it demonstrates that
acceleration is locally indistinguishable from gravity,
and then I stated what "locally" means. This is what
Wiki and other sources say.  Yet you say I am confused.
How so? About masses of BH's, I watch documentaries
which feature astrophysicists offering their opinions,
and they *uniformly* claim that BH's have mass. How
could it be otherwise if they're remnants of massive
collapsed stars? Not one makes Brent's claim, that
they're just geometric manifestations.  AG



I didn't say they lacked mass.  I said they lacked matter. 
Thus countering your assumption that gravity requires matter.

Brent


I could have said that gravity requires mass/energy. What's the
distinction between matter and mass? TIA, AG


Some things, e.g. black holes, have mass without matter (at least
as far as GR goes).

Brent


What's the distinction between matter and mass? AG


What's your problem.  Do  you just want to argument semantics.  I don't 
care if you want to call a black hole "matter", but nobody else does.  
Everybody else means localized packets of mass-energy in the form of 
fermions.


Brent

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Re: Principle of Equivalence



On Tuesday, July 14, 2020 at 2:50:12 PM UTC-6, Brent wrote:
>
>
>
> On 7/14/2020 12:22 PM, Alan Grayson wrote:
>
>
>
> On Tuesday, July 14, 2020 at 11:31:42 AM UTC-6, Brent wrote: 
>>
>>
>>
>> On 7/14/2020 3:34 AM, Lawrence Crowell wrote:
>>
>> On Monday, July 13, 2020 at 6:30:46 PM UTC-5, Alan Grayson wrote: 
>>>
>>>
>>>
>>> On Monday, July 13, 2020 at 5:19:30 PM UTC-6, Lawrence Crowell wrote: 

 On Monday, July 13, 2020 at 4:42:24 PM UTC-5, Alan Grayson wrote: 
>
>
>
> On Monday, July 13, 2020 at 1:42:49 PM UTC-6, Alan Grayson wrote: 
>>
>>
>>
>> On Monday, July 13, 2020 at 11:57:50 AM UTC-6, Brent wrote: 
>>>
>>>
>>>
>>> On 7/12/2020 11:50 PM, Alan Grayson wrote:
>>>
>>> There can be because it's consistent with the equations.  A black 
 hole doesn't include any matter.  General relativity is non-linear, 
 that's 
 why there can be non-flat cosmologies that contain no matter.  Of 
 course 
 there may be some different, better theory in which spacetime can't be 
 curved without matter...but it seems unlikely since we have good 
 evidence 
 that gravitational waves exist.

 Brent

>>>
>>> Yes, good evidence that gravitational waves exist, but as far I know 
>>> they're always associated with material interactions such as collisions 
>>> of 
>>> black holes. In the case of EM waves, I'd be more receptive of your 
>>> claim 
>>> that they can exist independent of charges and/or currents, but as far 
>>> as I 
>>> know there's no evidence of that. AG 
>>>

>>> But a collision of black holes does NOT involve matter.  Black holes 
>>> (as far as the theory goes) are purely geometric things, i.e. made of 
>>> empty 
>>> space.
>>>
>>> Brent
>>>
>>
>> How then does the BH at the center of our galaxy weigh in at 4 
>> million solar masses? AG 
>>
>
> It's measured by observing the rotation rates of stars near the 
> galactic core, and not so small by comparison with other BH's at the 
> center 
> of galaxies, called Super Massive BH's. AG 
>

 It is unfortunately apparent that you are pretty highly confused by 
 some of this. You need to sit down and read a comprehensive book or text 
 on 
 GR and related subjects. It is not going to be possible to clear this up 
 with dozens of email posts.

 LC 

>>>
>>> About the EP; I merely stated that it demonstrates that acceleration is 
>>> locally indistinguishable from gravity, and then I stated what "locally" 
>>> means. This is what Wiki and other sources say.  Yet you say I am confused. 
>>> How so? About masses of BH's, I watch documentaries which feature 
>>> astrophysicists offering their opinions, and they *uniformly* claim 
>>> that BH's have mass. How could it be otherwise if they're remnants of 
>>> massive collapsed stars? Not one makes Brent's claim, that they're just 
>>> geometric manifestations.  AG
>>>
>>
>> I didn't say they lacked mass.  I said they lacked matter.  Thus 
>> countering your assumption that gravity requires matter.
>>
>> Brent
>>
>
> I could have said that gravity requires mass/energy. What's the 
> distinction between matter and mass? TIA, AG 
>
>
> Some things, e.g. black holes, have mass without matter (at least as far 
> as GR goes).
>
> Brent
>

What's the distinction between matter and mass? AG 

-- 
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Re: Principle of Equivalence

2020-07-14 Thread 'Brent Meeker' via Everything List

On 7/14/2020 12:22 PM, Alan Grayson wrote:

On Tuesday, July 14, 2020 at 11:31:42 AM UTC-6, Brent wrote:

On 7/14/2020 3:34 AM, Lawrence Crowell wrote:

On Monday, July 13, 2020 at 6:30:46 PM UTC-5, Alan Grayson wrote:

On Monday, July 13, 2020 at 5:19:30 PM UTC-6, Lawrence
Crowell wrote:

On Monday, July 13, 2020 at 4:42:24 PM UTC-5, Alan
Grayson wrote:

On Monday, July 13, 2020 at 1:42:49 PM UTC-6, Alan
Grayson wrote:

On Monday, July 13, 2020 at 11:57:50 AM UTC-6,
Brent wrote:

On 7/12/2020 11:50 PM, Alan Grayson wrote:

There can be because it's consistent
with the equations. A black hole
doesn't include any matter. General
relativity is non-linear, that's why
there can be non-flat cosmologies that
contain no matter. Of course there may
be some different, better theory in
which spacetime can't be curved without
matter...but it seems unlikely since we
have good evidence that gravitational
waves exist.

Brent

Yes, good evidence that gravitational waves
exist, but as far I know they're always
associated with material interactions such
as collisions of black holes. In the case of
EM waves, I'd be more receptive of your
claim that they can exist independent of
charges and/or currents, but as far as I
know there's no evidence of that. AG

But a collision of black holes does NOT
involve matter. Black holes (as far as the
theory goes) are purely geometric things,
i.e. made of empty space.

Brent

How then does the BH at the center of our galaxy
weigh in at 4 million solar masses? AG

It's measured by observing the rotation rates of
stars near the galactic core, and not so small by
comparison with other BH's at the center of galaxies,
called Super Massive BH's. AG

It is unfortunately apparent that you are pretty highly
confused by some of this. You need to sit down and read a
comprehensive book or text on GR and related subjects. It
is not going to be possible to clear this up with dozens
of email posts.

About the EP; I merely stated that it demonstrates that
acceleration is locally indistinguishable from gravity, and
then I stated what "locally" means. This is what Wiki and
other sources say. Yet you say I am confused. How so? About
masses of BH's, I watch documentaries which feature
astrophysicists offering their opinions, and they *uniformly*
claim that BH's have mass. How could it be otherwise if
they're remnants of massive collapsed stars? Not one makes
Brent's claim, that they're just geometric manifestations. AG

I didn't say they lacked mass. I said they lacked matter. Thus
countering your assumption that gravity requires matter.

Brent

I could have said that gravity requires mass/energy. What's the
distinction between matter and mass? TIA, AG

Some things, e.g. black holes, have mass without matter (at least as far
as GR goes).

Brent

--
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Re: Principle of Equivalence



On Tuesday, July 14, 2020 at 9:43:11 AM UTC-6, Lawrence Crowell wrote:
>
> On Tuesday, July 14, 2020 at 5:55:52 AM UTC-5, Alan Grayson wrote:
>>
>>
>>
>> On Tuesday, July 14, 2020 at 4:34:00 AM UTC-6, Lawrence Crowell wrote:
>>>
>>> On Monday, July 13, 2020 at 6:30:46 PM UTC-5, Alan Grayson wrote:



 On Monday, July 13, 2020 at 5:19:30 PM UTC-6, Lawrence Crowell wrote:
>
> On Monday, July 13, 2020 at 4:42:24 PM UTC-5, Alan Grayson wrote:
>>
>>
>>
>> On Monday, July 13, 2020 at 1:42:49 PM UTC-6, Alan Grayson wrote:
>>>
>>>
>>>
>>> On Monday, July 13, 2020 at 11:57:50 AM UTC-6, Brent wrote:



 On 7/12/2020 11:50 PM, Alan Grayson wrote:

 There can be because it's consistent with the equations.  A black 
> hole doesn't include any matter.  General relativity is non-linear, 
> that's 
> why there can be non-flat cosmologies that contain no matter.  Of 
> course 
> there may be some different, better theory in which spacetime can't 
> be 
> curved without matter...but it seems unlikely since we have good 
> evidence 
> that gravitational waves exist.
>
> Brent
>

 Yes, good evidence that gravitational waves exist, but as far I 
 know they're always associated with material interactions such as 
 collisions of black holes. In the case of EM waves, I'd be more 
 receptive 
 of your claim that they can exist independent of charges and/or 
 currents, 
 but as far as I know there's no evidence of that. AG 

>
 But a collision of black holes does NOT involve matter.  Black 
 holes (as far as the theory goes) are purely geometric things, i.e. 
 made of 
 empty space.

 Brent

>>>
>>> How then does the BH at the center of our galaxy weigh in at 4 
>>> million solar masses? AG 
>>>
>>
>> It's measured by observing the rotation rates of stars near the 
>> galactic core, and not so small by comparison with other BH's at the 
>> center 
>> of galaxies, called Super Massive BH's. AG 
>>
>
> It is unfortunately apparent that you are pretty highly confused by 
> some of this. You need to sit down and read a comprehensive book or text 
> on 
> GR and related subjects. It is not going to be possible to clear this up 
> with dozens of email posts.
>
> LC 
>

 About the EP; I merely stated that it demonstrates that acceleration is 
 locally indistinguishable from gravity, and then I stated what "locally" 
 means. This is what Wiki and other sources say.  Yet you say I am 
 confused. 
 How so? About masses of BH's, I watch documentaries which feature 
 astrophysicists offering their opinions, and they *uniformly* claim 
 that BH's have mass. How could it be otherwise if they're remnants of 
 massive collapsed stars? Not one makes Brent's claim, that they're just 
 geometric manifestations.  AG

>>>
>>> Black hole mass is a pure spacetime physics. There is no material stuff 
>>> anyone can get their hands on. With the tortoise coordinate the distant 
>>> observer might say the matter-fields that made of a black hole exist, but 
>>> if one tried to reach them they always recede away. Black holes do not have 
>>> mass in a standard sense, though they have an ADM mass defined by the 
>>> curvature of spacetime.
>>>
>>
>> Generally, what resides inside a BH interacts gravitationally with what's 
>> exterior and is the remnant of a Type 1A supernova. It's unreachable, but 
>> has some correspondence with normal mass, which is why its mass can be 
>> estimated by its exterior effects, say for the one residing at the core of 
>> the Milky Way. I don't know how their masses are estimated when they are 
>> cores of distant galaxies. AG 
>>
>
> The interior does not interact with the exterior. The event horizon 
> prevents that. 
>

Then how can a BH interact gravitationally with objects external to the 
event horizon, or do you deny that? AG
 

> From the perspective of anyone in the exterior the interior of a black 
> hole is nothing more than a theoretical abstraction. It only exists as a 
> counter factual situation, where instead of remaining outside an observer 
> enters the BH/ 
>
> LC
>

-- 
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Re: Principle of Equivalence



On Tuesday, July 14, 2020 at 11:31:42 AM UTC-6, Brent wrote:
>
>
>
> On 7/14/2020 3:34 AM, Lawrence Crowell wrote:
>
> On Monday, July 13, 2020 at 6:30:46 PM UTC-5, Alan Grayson wrote: 
>>
>>
>>
>> On Monday, July 13, 2020 at 5:19:30 PM UTC-6, Lawrence Crowell wrote: 
>>>
>>> On Monday, July 13, 2020 at 4:42:24 PM UTC-5, Alan Grayson wrote: 



 On Monday, July 13, 2020 at 1:42:49 PM UTC-6, Alan Grayson wrote: 
>
>
>
> On Monday, July 13, 2020 at 11:57:50 AM UTC-6, Brent wrote: 
>>
>>
>>
>> On 7/12/2020 11:50 PM, Alan Grayson wrote:
>>
>> There can be because it's consistent with the equations.  A black 
>>> hole doesn't include any matter.  General relativity is non-linear, 
>>> that's 
>>> why there can be non-flat cosmologies that contain no matter.  Of 
>>> course 
>>> there may be some different, better theory in which spacetime can't be 
>>> curved without matter...but it seems unlikely since we have good 
>>> evidence 
>>> that gravitational waves exist.
>>>
>>> Brent
>>>
>>
>> Yes, good evidence that gravitational waves exist, but as far I know 
>> they're always associated with material interactions such as collisions 
>> of 
>> black holes. In the case of EM waves, I'd be more receptive of your 
>> claim 
>> that they can exist independent of charges and/or currents, but as far 
>> as I 
>> know there's no evidence of that. AG 
>>
>>>
>> But a collision of black holes does NOT involve matter.  Black holes 
>> (as far as the theory goes) are purely geometric things, i.e. made of 
>> empty 
>> space.
>>
>> Brent
>>
>
> How then does the BH at the center of our galaxy weigh in at 4 million 
> solar masses? AG 
>

 It's measured by observing the rotation rates of stars near the 
 galactic core, and not so small by comparison with other BH's at the 
 center 
 of galaxies, called Super Massive BH's. AG 

>>>
>>> It is unfortunately apparent that you are pretty highly confused by some 
>>> of this. You need to sit down and read a comprehensive book or text on GR 
>>> and related subjects. It is not going to be possible to clear this up with 
>>> dozens of email posts.
>>>
>>> LC 
>>>
>>
>> About the EP; I merely stated that it demonstrates that acceleration is 
>> locally indistinguishable from gravity, and then I stated what "locally" 
>> means. This is what Wiki and other sources say.  Yet you say I am confused. 
>> How so? About masses of BH's, I watch documentaries which feature 
>> astrophysicists offering their opinions, and they *uniformly* claim that 
>> BH's have mass. How could it be otherwise if they're remnants of massive 
>> collapsed stars? Not one makes Brent's claim, that they're just geometric 
>> manifestations.  AG
>>
>
> I didn't say they lacked mass.  I said they lacked matter.  Thus 
> countering your assumption that gravity requires matter.
>
> Brent
>

I could have said that gravity requires mass/energy. What's the distinction 
between matter and mass? TIA, AG 

>
>
> Black hole mass is a pure spacetime physics. There is no material stuff 
> anyone can get their hands on. With the tortoise coordinate the distant 
> observer might say the matter-fields that made of a black hole exist, but 
> if one tried to reach them they always recede away. Black holes do not have 
> mass in a standard sense, though they have an ADM mass defined by the 
> curvature of spacetime.
>
> LC 
> -- 
> You received this message because you are subscribed to the Google Groups 
> "Everything List" group.
> To unsubscribe from this group and stop receiving emails from it, send an 
> email to everyth...@googlegroups.com .
> To view this discussion on the web visit 
> https://groups.google.com/d/msgid/everything-list/73eaaefd-b59a-4c4e-88bd-7b2aac7c1d0bo%40googlegroups.com
>  
> 
> .
>
>
>

-- 
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Re: Principle of Equivalence

2020-07-14 Thread 'Brent Meeker' via Everything List

On 7/14/2020 3:34 AM, Lawrence Crowell wrote:

On Monday, July 13, 2020 at 6:30:46 PM UTC-5, Alan Grayson wrote:

On Monday, July 13, 2020 at 5:19:30 PM UTC-6, Lawrence Crowell wrote:

On Monday, July 13, 2020 at 4:42:24 PM UTC-5, Alan Grayson wrote:

On Monday, July 13, 2020 at 1:42:49 PM UTC-6, Alan Grayson
wrote:

On Monday, July 13, 2020 at 11:57:50 AM UTC-6, Brent
wrote:

On 7/12/2020 11:50 PM, Alan Grayson wrote:

There can be because it's consistent with the
equations. A black hole doesn't include any
matter. General relativity is non-linear,
that's why there can be non-flat cosmologies
that contain no matter. Of course there may
be some different, better theory in which
spacetime can't be curved without
matter...but it seems unlikely since we have
good evidence that gravitational waves exist.

Brent

Yes, good evidence that gravitational waves
exist, but as far I know they're always
associated with material interactions such as
collisions of black holes. In the case of EM
waves, I'd be more receptive of your claim that
they can exist independent of charges and/or
currents, but as far as I know there's no
evidence of that. AG

But a collision of black holes does NOT involve
matter. Black holes (as far as the theory goes)
are purely geometric things, i.e. made of empty space.

Brent

How then does the BH at the center of our galaxy weigh
in at 4 million solar masses? AG

It's measured by observing the rotation rates of stars
near the galactic core, and not so small by comparison
with other BH's at the center of galaxies, called Super
Massive BH's. AG

It is unfortunately apparent that you are pretty highly
confused by some of this. You need to sit down and read a
comprehensive book or text on GR and related subjects. It is
not going to be possible to clear this up with dozens of email
posts.

About the EP; I merely stated that it demonstrates that
acceleration is locally indistinguishable from gravity, and then I
stated what "locally" means. This is what Wiki and other sources
say. Yet you say I am confused. How so? About masses of BH's, I
watch documentaries which feature astrophysicists offering their
opinions, and they *uniformly* claim that BH's have mass. How
could it be otherwise if they're remnants of massive collapsed
stars? Not one makes Brent's claim, that they're just geometric
manifestations. AG

I didn't say they lacked mass. I said they lacked matter. Thus
countering your assumption that gravity requires matter.

Brent

Black hole mass is a pure spacetime physics. There is no material
stuff anyone can get their hands on. With the tortoise coordinate the
distant observer might say the matter-fields that made of a black hole
exist, but if one tried to reach them they always recede away. Black
holes do not have mass in a standard sense, though they have an ADM
mass defined by the curvature of spacetime.

LC
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Re: Principle of Equivalence

2020-07-14 Thread Lawrence Crowell

On Tuesday, July 14, 2020 at 5:55:52 AM UTC-5, Alan Grayson wrote:
>
>
>
> On Tuesday, July 14, 2020 at 4:34:00 AM UTC-6, Lawrence Crowell wrote:
>>
>> On Monday, July 13, 2020 at 6:30:46 PM UTC-5, Alan Grayson wrote:
>>>
>>>
>>>
>>> On Monday, July 13, 2020 at 5:19:30 PM UTC-6, Lawrence Crowell wrote:

 On Monday, July 13, 2020 at 4:42:24 PM UTC-5, Alan Grayson wrote:
>
>
>
> On Monday, July 13, 2020 at 1:42:49 PM UTC-6, Alan Grayson wrote:
>>
>>
>>
>> On Monday, July 13, 2020 at 11:57:50 AM UTC-6, Brent wrote:
>>>
>>>
>>>
>>> On 7/12/2020 11:50 PM, Alan Grayson wrote:
>>>
>>> There can be because it's consistent with the equations.  A black 
 hole doesn't include any matter.  General relativity is non-linear, 
 that's 
 why there can be non-flat cosmologies that contain no matter.  Of 
 course 
 there may be some different, better theory in which spacetime can't be 
 curved without matter...but it seems unlikely since we have good 
 evidence 
 that gravitational waves exist.

 Brent

>>>
>>> Yes, good evidence that gravitational waves exist, but as far I know 
>>> they're always associated with material interactions such as collisions 
>>> of 
>>> black holes. In the case of EM waves, I'd be more receptive of your 
>>> claim 
>>> that they can exist independent of charges and/or currents, but as far 
>>> as I 
>>> know there's no evidence of that. AG 
>>>

>>> But a collision of black holes does NOT involve matter.  Black holes 
>>> (as far as the theory goes) are purely geometric things, i.e. made of 
>>> empty 
>>> space.
>>>
>>> Brent
>>>
>>
>> How then does the BH at the center of our galaxy weigh in at 4 
>> million solar masses? AG 
>>
>
> It's measured by observing the rotation rates of stars near the 
> galactic core, and not so small by comparison with other BH's at the 
> center 
> of galaxies, called Super Massive BH's. AG 
>

 It is unfortunately apparent that you are pretty highly confused by 
 some of this. You need to sit down and read a comprehensive book or text 
 on 
 GR and related subjects. It is not going to be possible to clear this up 
 with dozens of email posts.

 LC 

>>>
>>> About the EP; I merely stated that it demonstrates that acceleration is 
>>> locally indistinguishable from gravity, and then I stated what "locally" 
>>> means. This is what Wiki and other sources say.  Yet you say I am confused. 
>>> How so? About masses of BH's, I watch documentaries which feature 
>>> astrophysicists offering their opinions, and they *uniformly* claim 
>>> that BH's have mass. How could it be otherwise if they're remnants of 
>>> massive collapsed stars? Not one makes Brent's claim, that they're just 
>>> geometric manifestations.  AG
>>>
>>
>> Black hole mass is a pure spacetime physics. There is no material stuff 
>> anyone can get their hands on. With the tortoise coordinate the distant 
>> observer might say the matter-fields that made of a black hole exist, but 
>> if one tried to reach them they always recede away. Black holes do not have 
>> mass in a standard sense, though they have an ADM mass defined by the 
>> curvature of spacetime.
>>
>
> Generally, what resides inside a BH interacts gravitationally with what's 
> exterior and is the remnant of a Type 1A supernova. It's unreachable, but 
> has some correspondence with normal mass, which is why its mass can be 
> estimated by its exterior effects, say for the one residing at the core of 
> the Milky Way. I don't know how their masses are estimated when they are 
> cores of distant galaxies. AG 
>

The interior does not interact with the exterior. The event horizon 
prevents that. From the perspective of anyone in the exterior the interior 
of a black hole is nothing more than a theoretical abstraction. It only 
exists as a counter factual situation, where instead of remaining outside 
an observer enters the BH/ 

LC

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Re: Principle of Equivalence



On Tuesday, July 14, 2020 at 4:34:00 AM UTC-6, Lawrence Crowell wrote:
>
> On Monday, July 13, 2020 at 6:30:46 PM UTC-5, Alan Grayson wrote:
>>
>>
>>
>> On Monday, July 13, 2020 at 5:19:30 PM UTC-6, Lawrence Crowell wrote:
>>>
>>> On Monday, July 13, 2020 at 4:42:24 PM UTC-5, Alan Grayson wrote:



 On Monday, July 13, 2020 at 1:42:49 PM UTC-6, Alan Grayson wrote:
>
>
>
> On Monday, July 13, 2020 at 11:57:50 AM UTC-6, Brent wrote:
>>
>>
>>
>> On 7/12/2020 11:50 PM, Alan Grayson wrote:
>>
>> There can be because it's consistent with the equations.  A black 
>>> hole doesn't include any matter.  General relativity is non-linear, 
>>> that's 
>>> why there can be non-flat cosmologies that contain no matter.  Of 
>>> course 
>>> there may be some different, better theory in which spacetime can't be 
>>> curved without matter...but it seems unlikely since we have good 
>>> evidence 
>>> that gravitational waves exist.
>>>
>>> Brent
>>>
>>
>> Yes, good evidence that gravitational waves exist, but as far I know 
>> they're always associated with material interactions such as collisions 
>> of 
>> black holes. In the case of EM waves, I'd be more receptive of your 
>> claim 
>> that they can exist independent of charges and/or currents, but as far 
>> as I 
>> know there's no evidence of that. AG 
>>
>>>
>> But a collision of black holes does NOT involve matter.  Black holes 
>> (as far as the theory goes) are purely geometric things, i.e. made of 
>> empty 
>> space.
>>
>> Brent
>>
>
> How then does the BH at the center of our galaxy weigh in at 4 million 
> solar masses? AG 
>

 It's measured by observing the rotation rates of stars near the 
 galactic core, and not so small by comparison with other BH's at the 
 center 
 of galaxies, called Super Massive BH's. AG 

>>>
>>> It is unfortunately apparent that you are pretty highly confused by some 
>>> of this. You need to sit down and read a comprehensive book or text on GR 
>>> and related subjects. It is not going to be possible to clear this up with 
>>> dozens of email posts.
>>>
>>> LC 
>>>
>>
>> About the EP; I merely stated that it demonstrates that acceleration is 
>> locally indistinguishable from gravity, and then I stated what "locally" 
>> means. This is what Wiki and other sources say.  Yet you say I am confused. 
>> How so? About masses of BH's, I watch documentaries which feature 
>> astrophysicists offering their opinions, and they *uniformly* claim that 
>> BH's have mass. How could it be otherwise if they're remnants of massive 
>> collapsed stars? Not one makes Brent's claim, that they're just geometric 
>> manifestations.  AG
>>
>
> Black hole mass is a pure spacetime physics. There is no material stuff 
> anyone can get their hands on. With the tortoise coordinate the distant 
> observer might say the matter-fields that made of a black hole exist, but 
> if one tried to reach them they always recede away. Black holes do not have 
> mass in a standard sense, though they have an ADM mass defined by the 
> curvature of spacetime.
>

Generally, what resides inside a BH interacts gravitationally with what's 
exterior and is the remnant of a Type 1A supernova. It's unreachable, but 
has some correspondence with normal mass, which is why its mass can be 
estimated by its exterior effects, say for the one residing at the core of 
the Milky Way. I don't know how their masses are estimated when they are 
cores of distant galaxies. AG 

>
> LC 
>

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Re: Principle of Equivalence

2020-07-14 Thread Lawrence Crowell

On Monday, July 13, 2020 at 6:30:46 PM UTC-5, Alan Grayson wrote:
>
>
>
> On Monday, July 13, 2020 at 5:19:30 PM UTC-6, Lawrence Crowell wrote:
>>
>> On Monday, July 13, 2020 at 4:42:24 PM UTC-5, Alan Grayson wrote:
>>>
>>>
>>>
>>> On Monday, July 13, 2020 at 1:42:49 PM UTC-6, Alan Grayson wrote:



 On Monday, July 13, 2020 at 11:57:50 AM UTC-6, Brent wrote:
>
>
>
> On 7/12/2020 11:50 PM, Alan Grayson wrote:
>
> There can be because it's consistent with the equations.  A black hole 
>> doesn't include any matter.  General relativity is non-linear, that's 
>> why 
>> there can be non-flat cosmologies that contain no matter.  Of course 
>> there 
>> may be some different, better theory in which spacetime can't be curved 
>> without matter...but it seems unlikely since we have good evidence that 
>> gravitational waves exist.
>>
>> Brent
>>
>
> Yes, good evidence that gravitational waves exist, but as far I know 
> they're always associated with material interactions such as collisions 
> of 
> black holes. In the case of EM waves, I'd be more receptive of your claim 
> that they can exist independent of charges and/or currents, but as far as 
> I 
> know there's no evidence of that. AG 
>
>>
> But a collision of black holes does NOT involve matter.  Black holes 
> (as far as the theory goes) are purely geometric things, i.e. made of 
> empty 
> space.
>
> Brent
>

 How then does the BH at the center of our galaxy weigh in at 4 million 
 solar masses? AG 

>>>
>>> It's measured by observing the rotation rates of stars near the galactic 
>>> core, and not so small by comparison with other BH's at the center of 
>>> galaxies, called Super Massive BH's. AG 
>>>
>>
>> It is unfortunately apparent that you are pretty highly confused by some 
>> of this. You need to sit down and read a comprehensive book or text on GR 
>> and related subjects. It is not going to be possible to clear this up with 
>> dozens of email posts.
>>
>> LC 
>>
>
> About the EP; I merely stated that it demonstrates that acceleration is 
> locally indistinguishable from gravity, and then I stated what "locally" 
> means. This is what Wiki and other sources say.  Yet you say I am confused. 
> How so? About masses of BH's, I watch documentaries which feature 
> astrophysicists offering their opinions, and they *uniformly* claim that 
> BH's have mass. How could it be otherwise if they're remnants of massive 
> collapsed stars? Not one makes Brent's claim, that they're just geometric 
> manifestations.  AG
>

Black hole mass is a pure spacetime physics. There is no material stuff 
anyone can get their hands on. With the tortoise coordinate the distant 
observer might say the matter-fields that made of a black hole exist, but 
if one tried to reach them they always recede away. Black holes do not have 
mass in a standard sense, though they have an ADM mass defined by the 
curvature of spacetime.

LC 

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Re: Principle of Equivalence



On Monday, July 13, 2020 at 5:19:30 PM UTC-6, Lawrence Crowell wrote:
>
> On Monday, July 13, 2020 at 4:42:24 PM UTC-5, Alan Grayson wrote:
>>
>>
>>
>> On Monday, July 13, 2020 at 1:42:49 PM UTC-6, Alan Grayson wrote:
>>>
>>>
>>>
>>> On Monday, July 13, 2020 at 11:57:50 AM UTC-6, Brent wrote:
>>>>
>>>>
>>>>
>>>> On 7/12/2020 11:50 PM, Alan Grayson wrote:
>>>>
>>>> There can be because it's consistent with the equations.  A black hole 
>>>>> doesn't include any matter.  General relativity is non-linear, that's why 
>>>>> there can be non-flat cosmologies that contain no matter.  Of course 
>>>>> there 
>>>>> may be some different, better theory in which spacetime can't be curved 
>>>>> without matter...but it seems unlikely since we have good evidence that 
>>>>> gravitational waves exist.
>>>>>
>>>>> Brent
>>>>>
>>>>
>>>> Yes, good evidence that gravitational waves exist, but as far I know 
>>>> they're always associated with material interactions such as collisions of 
>>>> black holes. In the case of EM waves, I'd be more receptive of your claim 
>>>> that they can exist independent of charges and/or currents, but as far as 
>>>> I 
>>>> know there's no evidence of that. AG 
>>>>
>>>>>
>>>> But a collision of black holes does NOT involve matter.  Black holes 
>>>> (as far as the theory goes) are purely geometric things, i.e. made of 
>>>> empty 
>>>> space.
>>>>
>>>> Brent
>>>>
>>>
>>> How then does the BH at the center of our galaxy weigh in at 4 million 
>>> solar masses? AG 
>>>
>>
>> It's measured by observing the rotation rates of stars near the galactic 
>> core, and not so small by comparison with other BH's at the center of 
>> galaxies, called Super Massive BH's. AG 
>>
>
> It is unfortunately apparent that you are pretty highly confused by some 
> of this. You need to sit down and read a comprehensive book or text on GR 
> and related subjects. It is not going to be possible to clear this up with 
> dozens of email posts.
>
> LC 
>

In reviewing Wiki's article on the Equivalence Principle, I see the details 
there are not exactly what I stated. But it doesn't really matter, except 
possibly for a purist, in the sense that I was trying to see how Einstein 
could have inferred curvature of space-time from the EP, using the enclosed 
elevator example subject to uniform acceleration. What I wrote seems 
sufficient to my objective. I am not confused. AG

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Re: Principle of Equivalence



On Monday, July 13, 2020 at 5:30:46 PM UTC-6, Alan Grayson wrote:
>
>
>
> On Monday, July 13, 2020 at 5:19:30 PM UTC-6, Lawrence Crowell wrote:
>>
>> On Monday, July 13, 2020 at 4:42:24 PM UTC-5, Alan Grayson wrote:
>>>
>>>
>>>
>>> On Monday, July 13, 2020 at 1:42:49 PM UTC-6, Alan Grayson wrote:



 On Monday, July 13, 2020 at 11:57:50 AM UTC-6, Brent wrote:
>
>
>
> On 7/12/2020 11:50 PM, Alan Grayson wrote:
>
> There can be because it's consistent with the equations.  A black hole 
>> doesn't include any matter.  General relativity is non-linear, that's 
>> why 
>> there can be non-flat cosmologies that contain no matter.  Of course 
>> there 
>> may be some different, better theory in which spacetime can't be curved 
>> without matter...but it seems unlikely since we have good evidence that 
>> gravitational waves exist.
>>
>> Brent
>>
>
> Yes, good evidence that gravitational waves exist, but as far I know 
> they're always associated with material interactions such as collisions 
> of 
> black holes. In the case of EM waves, I'd be more receptive of your claim 
> that they can exist independent of charges and/or currents, but as far as 
> I 
> know there's no evidence of that. AG 
>
>>
> But a collision of black holes does NOT involve matter.  Black holes 
> (as far as the theory goes) are purely geometric things, i.e. made of 
> empty 
> space.
>
> Brent
>

 How then does the BH at the center of our galaxy weigh in at 4 million 
 solar masses? AG 

>>>
>>> It's measured by observing the rotation rates of stars near the galactic 
>>> core, and not so small by comparison with other BH's at the center of 
>>> galaxies, called Super Massive BH's. AG 
>>>
>>
>> It is unfortunately apparent that you are pretty highly confused by some 
>> of this. You need to sit down and read a comprehensive book or text on GR 
>> and related subjects. It is not going to be possible to clear this up with 
>> dozens of email posts.
>>
>> LC 
>>
>
> About the EP; I merely stated that it demonstrates that acceleration is 
> locally indistinguishable from gravity, and then I stated what "locally" 
> means. This is what Wiki and other sources say.  Yet you say I am confused. 
> How so? About masses of BH's, I watch documentaries which feature 
> astrophysicists offering their opinions, and they *uniformly* claim that 
> BH's have mass. How could it be otherwise if they're remnants of massive 
> collapsed stars? Not one makes Brent's claim, that they're just geometric 
> manifestations.  AG
>

About the EP, I was careful to state that *uniform* acceleration is locally 
equivalent to gravity. I suggest you edit the Wiki article if you think 
it's "confused" and then post it here. I did state that the existence of 
gravity implies matter/energy, and you might object to that. But, IMO, 
you're misinterpreting what the GR field equations (and ME's) imply about 
the viability of wave motion in a vacuum. I see no reason to assume no 
source disturbance for the wave. AG

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Re: Principle of Equivalence

On Monday, July 13, 2020 at 5:19:30 PM UTC-6, Lawrence Crowell wrote:
>
> On Monday, July 13, 2020 at 4:42:24 PM UTC-5, Alan Grayson wrote:
>>
>>
>>
>> On Monday, July 13, 2020 at 1:42:49 PM UTC-6, Alan Grayson wrote:
>>>
>>>
>>>
>>> On Monday, July 13, 2020 at 11:57:50 AM UTC-6, Brent wrote:

 On 7/12/2020 11:50 PM, Alan Grayson wrote:

 There can be because it's consistent with the equations.  A black hole 
> doesn't include any matter.  General relativity is non-linear, that's why 
> there can be non-flat cosmologies that contain no matter.  Of course 
> there 
> may be some different, better theory in which spacetime can't be curved 
> without matter...but it seems unlikely since we have good evidence that 
> gravitational waves exist.
>
> Brent
>

 Yes, good evidence that gravitational waves exist, but as far I know 
 they're always associated with material interactions such as collisions of 
 black holes. In the case of EM waves, I'd be more receptive of your claim 
 that they can exist independent of charges and/or currents, but as far as 
 I 
 know there's no evidence of that. AG 

>
 But a collision of black holes does NOT involve matter.  Black holes 
 (as far as the theory goes) are purely geometric things, i.e. made of 
 empty 
 space.

 Brent

>>>
>>> How then does the BH at the center of our galaxy weigh in at 4 million 
>>> solar masses? AG 
>>>
>>
>> It's measured by observing the rotation rates of stars near the galactic 
>> core, and not so small by comparison with other BH's at the center of 
>> galaxies, called Super Massive BH's. AG 
>>
>
> It is unfortunately apparent that you are pretty highly confused by some 
> of this. You need to sit down and read a comprehensive book or text on GR 
> and related subjects. It is not going to be possible to clear this up with 
> dozens of email posts.
>
> LC 
>

About the EP; I merely stated that it demonstrates that acceleration is 
locally indistinguishable from gravity, and then I stated what "locally" 
means. This is what Wiki and other sources say.  Yet you say I am confused. 
How so? About masses of BH's, I watch documentaries which feature 
astrophysicists offering their opinions, and they *uniformly* claim that 
BH's have mass. How could it be otherwise if they're remnants of massive 
collapsed stars? Not one makes Brent's claim, that they're just geometric 
manifestations.  AG

-- 
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Re: Principle of Equivalence



On Monday, July 13, 2020 at 3:42:24 PM UTC-6, Alan Grayson wrote:
>
>
>
> On Monday, July 13, 2020 at 1:42:49 PM UTC-6, Alan Grayson wrote:
>>
>>
>>
>> On Monday, July 13, 2020 at 11:57:50 AM UTC-6, Brent wrote:
>>>
>>>
>>>
>>> On 7/12/2020 11:50 PM, Alan Grayson wrote:
>>>
>>> There can be because it's consistent with the equations.  A black hole 
 doesn't include any matter.  General relativity is non-linear, that's why 
 there can be non-flat cosmologies that contain no matter.  Of course there 
 may be some different, better theory in which spacetime can't be curved 
 without matter...but it seems unlikely since we have good evidence that 
 gravitational waves exist.

 Brent

>>>
>>> Yes, good evidence that gravitational waves exist, but as far I know 
>>> they're always associated with material interactions such as collisions of 
>>> black holes. In the case of EM waves, I'd be more receptive of your claim 
>>> that they can exist independent of charges and/or currents, but as far as I 
>>> know there's no evidence of that. AG 
>>>

>>> But a collision of black holes does NOT involve matter.  Black holes (as 
>>> far as the theory goes) are purely geometric things, i.e. made of empty 
>>> space.
>>>
>>> Brent
>>>
>>
>> How then does the BH at the center of our galaxy weigh in at 4 million 
>> solar masses? AG 
>>
>
> It's measured by observing the rotation rates of stars near the galactic 
> core, and not so small by comparison with other BH's at the center of 
> galaxies, called Super Massive BH's. AG 
>

Correction; I meant that our BH is small by comparison to Super Massive 
BH's, which are orders of magnitude larger than 4 million solar masses. AG 

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Re: Principle of Equivalence

2020-07-13 Thread Lawrence Crowell

On Monday, July 13, 2020 at 4:42:24 PM UTC-5, Alan Grayson wrote:
>
>
>
> On Monday, July 13, 2020 at 1:42:49 PM UTC-6, Alan Grayson wrote:
>>
>>
>>
>> On Monday, July 13, 2020 at 11:57:50 AM UTC-6, Brent wrote:
>>>
>>>
>>>
>>> On 7/12/2020 11:50 PM, Alan Grayson wrote:
>>>
>>> There can be because it's consistent with the equations.  A black hole 
 doesn't include any matter.  General relativity is non-linear, that's why 
 there can be non-flat cosmologies that contain no matter.  Of course there 
 may be some different, better theory in which spacetime can't be curved 
 without matter...but it seems unlikely since we have good evidence that 
 gravitational waves exist.

 Brent

>>>
>>> Yes, good evidence that gravitational waves exist, but as far I know 
>>> they're always associated with material interactions such as collisions of 
>>> black holes. In the case of EM waves, I'd be more receptive of your claim 
>>> that they can exist independent of charges and/or currents, but as far as I 
>>> know there's no evidence of that. AG 
>>>

>>> But a collision of black holes does NOT involve matter.  Black holes (as 
>>> far as the theory goes) are purely geometric things, i.e. made of empty 
>>> space.
>>>
>>> Brent
>>>
>>
>> How then does the BH at the center of our galaxy weigh in at 4 million 
>> solar masses? AG 
>>
>
> It's measured by observing the rotation rates of stars near the galactic 
> core, and not so small by comparison with other BH's at the center of 
> galaxies, called Super Massive BH's. AG 
>

It is unfortunately apparent that you are pretty highly confused by some of 
this. You need to sit down and read a comprehensive book or text on GR and 
related subjects. It is not going to be possible to clear this up with 
dozens of email posts.

LC 

-- 
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Re: Principle of Equivalence



On Monday, July 13, 2020 at 3:42:24 PM UTC-6, Alan Grayson wrote:
>
>
>
> On Monday, July 13, 2020 at 1:42:49 PM UTC-6, Alan Grayson wrote:
>>
>>
>>
>> On Monday, July 13, 2020 at 11:57:50 AM UTC-6, Brent wrote:
>>>
>>>
>>>
>>> On 7/12/2020 11:50 PM, Alan Grayson wrote:
>>>
>>> There can be because it's consistent with the equations.  A black hole 
 doesn't include any matter.  General relativity is non-linear, that's why 
 there can be non-flat cosmologies that contain no matter.  Of course there 
 may be some different, better theory in which spacetime can't be curved 
 without matter...but it seems unlikely since we have good evidence that 
 gravitational waves exist.

 Brent

>>>
>>> Yes, good evidence that gravitational waves exist, but as far I know 
>>> they're always associated with material interactions such as collisions of 
>>> black holes. In the case of EM waves, I'd be more receptive of your claim 
>>> that they can exist independent of charges and/or currents, but as far as I 
>>> know there's no evidence of that. AG 
>>>

>>> But a collision of black holes does NOT involve matter.  Black holes (as 
>>> far as the theory goes) are purely geometric things, i.e. made of empty 
>>> space.
>>>
>>> Brent
>>>
>>
>> How then does the BH at the center of our galaxy weigh in at 4 million 
>> solar masses? AG 
>>
>
> It's measured by observing the rotation rates of stars near the galactic 
> core, and not so small by comparison with other BH's at the center of 
> galaxies, called Super Massive BH's. AG 
>

If you assume zero mass solutions in GR, or no charges or currents in EM, 
the solutions you get are expected; namely, that in regions of space or 
space-time which are vacuums, waves can propagate.  AG

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Re: Principle of Equivalence



On Monday, July 13, 2020 at 1:42:49 PM UTC-6, Alan Grayson wrote:
>
>
>
> On Monday, July 13, 2020 at 11:57:50 AM UTC-6, Brent wrote:
>>
>>
>>
>> On 7/12/2020 11:50 PM, Alan Grayson wrote:
>>
>> There can be because it's consistent with the equations.  A black hole 
>>> doesn't include any matter.  General relativity is non-linear, that's why 
>>> there can be non-flat cosmologies that contain no matter.  Of course there 
>>> may be some different, better theory in which spacetime can't be curved 
>>> without matter...but it seems unlikely since we have good evidence that 
>>> gravitational waves exist.
>>>
>>> Brent
>>>
>>
>> Yes, good evidence that gravitational waves exist, but as far I know 
>> they're always associated with material interactions such as collisions of 
>> black holes. In the case of EM waves, I'd be more receptive of your claim 
>> that they can exist independent of charges and/or currents, but as far as I 
>> know there's no evidence of that. AG 
>>
>>>
>> But a collision of black holes does NOT involve matter.  Black holes (as 
>> far as the theory goes) are purely geometric things, i.e. made of empty 
>> space.
>>
>> Brent
>>
>
> How then does the BH at the center of our galaxy weigh in at 4 million 
> solar masses? AG 
>

It's measured by observing the rotation rates of stars near the galactic 
core, and not so small by comparison with other BH's at the center of 
galaxies, called Super Massive BH's. AG 

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Re: Principle of Equivalence



On Monday, July 13, 2020 at 11:57:50 AM UTC-6, Brent wrote:
>
>
>
> On 7/12/2020 11:50 PM, Alan Grayson wrote:
>
> There can be because it's consistent with the equations.  A black hole 
>> doesn't include any matter.  General relativity is non-linear, that's why 
>> there can be non-flat cosmologies that contain no matter.  Of course there 
>> may be some different, better theory in which spacetime can't be curved 
>> without matter...but it seems unlikely since we have good evidence that 
>> gravitational waves exist.
>>
>> Brent
>>
>
> Yes, good evidence that gravitational waves exist, but as far I know 
> they're always associated with material interactions such as collisions of 
> black holes. In the case of EM waves, I'd be more receptive of your claim 
> that they can exist independent of charges and/or currents, but as far as I 
> know there's no evidence of that. AG 
>
>>
> But a collision of black holes does NOT involve matter.  Black holes (as 
> far as the theory goes) are purely geometric things, i.e. made of empty 
> space.
>
> Brent
>

How then does the BH at the center of our galaxy weigh in at 4 million 
solar masses? AG 

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Re: Principle of Equivalence

2020-07-13 Thread 'Brent Meeker' via Everything List




On 7/12/2020 11:50 PM, Alan Grayson wrote:


There can be because it's consistent with the equations.  A black
hole doesn't include any matter.  General relativity is
non-linear, that's why there can be non-flat cosmologies that
contain no matter.  Of course there may be some different, better
theory in which spacetime can't be curved without matter...but it
seems unlikely since we have good evidence that gravitational
waves exist.

Brent


Yes, good evidence that gravitational waves exist, but as far I know 
they're always associated with material interactions such as 
collisions of black holes. In the case of EM waves, I'd be more 
receptive of your claim that they can exist independent of charges 
and/or currents, but as far as I know there's no evidence of that. AG




But a collision of black holes does NOT involve matter.  Black holes (as 
far as the theory goes) are purely geometric things, i.e. made of empty 
space.


Brent

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Re: Principle of Equivalence



On Sunday, July 12, 2020 at 12:35:32 PM UTC-6, Brent wrote:
>
>
>
> On 7/12/2020 12:37 AM, Alan Grayson wrote:
>
>
>
> On Saturday, July 11, 2020 at 10:30:21 PM UTC-6, Alan Grayson wrote: 
>>
>>
>>
>> On Saturday, July 11, 2020 at 10:20:54 PM UTC-6, Brent wrote: 
>>>
>>>
>>>
>>> On 7/11/2020 9:00 PM, Alan Grayson wrote:
>>>
>>>
>>>
>>> On Saturday, July 11, 2020 at 9:49:31 PM UTC-6, Brent wrote: 
>>>>
>>>>
>>>>
>>>> On 7/11/2020 8:07 PM, Alan Grayson wrote:
>>>>
>>>>
>>>>
>>>> On Saturday, July 11, 2020 at 8:41:21 PM UTC-6, Brent wrote: 
>>>>>
>>>>>
>>>>>
>>>>> On 7/11/2020 4:29 PM, Alan Grayson wrote:
>>>>>
>>>>>
>>>>>
>>>>> On Saturday, July 11, 2020 at 5:05:02 PM UTC-6, Brent wrote: 
>>>>>>
>>>>>>
>>>>>>
>>>>>> On 7/11/2020 12:54 AM, Alan Grayson wrote:
>>>>>>
>>>>>>
>>>>>>
>>>>>> On Tuesday, July 7, 2020 at 10:06:44 PM UTC-6, Alan Grayson wrote: 
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>> On Tuesday, July 7, 2020 at 8:50:50 PM UTC-6, Alan Grayson wrote: 
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>> On Tuesday, July 7, 2020 at 8:05:28 PM UTC-6, Bruce wrote: 
>>>>>>>>>
>>>>>>>>> On Wed, Jul 1, 2020 at 4:18 PM Alan Grayson  
>>>>>>>>> wrote:
>>>>>>>>>
>>>>>>>>>> How, exactly, is the Principle of Equivalence used by Einstein to 
>>>>>>>>>> develop GR? TIA, AG
>>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> This lecture by Sean Carroll should answer all your questions:
>>>>>>>>>
>>>>>>>>> URL: https://wp.me/p2WMeM-3vl
>>>>>>>>>
>>>>>>>>> Bruce
>>>>>>>>>
>>>>>>>>
>>>>>>>> I'll watch it tonight, but I think I've figured it out; 
>>>>>>>> specifically, the EP implies space-time is curved by the presence of 
>>>>>>>> mass/energy (and this is independent of the need to express the laws 
>>>>>>>> of 
>>>>>>>> physics in a coordinate independent way via tensors). AG
>>>>>>>>
>>>>>>>
>>>>>>> Here's my reasoning regarding the EP; if an observer is in a box 
>>>>>>> subject to uniform acceleration, a beam of light starting on the 
>>>>>>> extreme 
>>>>>>> left side (moving transverse or perpendicular to the acceleration 
>>>>>>> vector), 
>>>>>>> will hit a lower point on the right side, showing that uniform 
>>>>>>> acceleration 
>>>>>>> results in curved paths in space-time. But if this result is identical 
>>>>>>> to 
>>>>>>> gravity, locally, it means that curved paths in space-time are produced 
>>>>>>> by, 
>>>>>>> or are equivalent to gravity. 
>>>>>>>
>>>>>>
>>>>>> That makes no sense.  You're saying that because curved paths can be 
>>>>>> produced two different ways then they must always be produced the second 
>>>>>> way.
>>>>>>
>>>>>>
>>>>>> BUT gravity is only observed in the presence of mass/energy. ERGO, 
>>>>>>> the EP implies mass/energy curves space-time. AG 
>>>>>>>
>>>>>>
>>>>>> And that's not even true.  Gravitational waves can propagate thru the 
>>>>>> vacuum.  The Schwarzschild solution is for empty space.  De Sitter space 
>>>>>> is 
>>>>>> an empty cosmos.
>>>>>>
>>>>>
>>>>> Light can propagate through empty space, but it can't arise from 
>>>>> nothing. Same presumably for gravitational waves. AG 
>>>>>
>>>>>
>>>>> Are you going to say the same thin

Re: Principle of Equivalence



On Sunday, July 12, 2020 at 4:37:15 PM UTC-6, Lawrence Crowell wrote:
>
> I have not followed this thread much. I get the impression there is a lot 
> of confusion. 
>
> The equivalence principle states there is no distinguishing difference 
> between a frame far away in flat spacetime and one in a region of spacetime 
> that is curved so long as the frame is small in extent. In other words, it 
> there is a curvature R and the dimensions of the frame are d then d << √R. 
> This will mean that any test masses in this small frame will be on 
> co-parallel geodesics and the local physics is no different than if you are 
> on a frame in very distant flat spacetime. The converse of this then is 
> that being on an accelerated frame is indistiguishable from being held 
> fixed in a gravitational field. The surface of the Earth does that for us. 
> Then comparing gravity with acceleration this way the implication is that 
> inertial mass is equal to gravitational mass. The previous case indicates a 
> way forwards to general relativity with local frames or patches that are 
> meshed together in a coordinate atlas and transition function that define 
> connection coefficients and curvature.
>
> What you write above is not substantially different from my description of 
the EP. AG
 

> Is there a better way to do this, Yes! this is what I have been working 
> on. Instead of a single small inertial frame consider two frames and in 
> each there is one of each EPR pair, The easy part is to show that the 
> entanglement is constant so long as the two frames are on geodesic motion. 
> This is a sort of extended EP which is potentially useful for quantum 
> gravitation. This is in particular if spacetime is built up from quantum 
> entangled states. Things becomes much more difficult when black hole 
> horizons enter the picture. 
>
> The standard EP is not that hard to understand, and in weak gravitation 
> the obvious example of this are weightless objects and astronauts in 
> spacecraft and the ISS. In effect this is moving horizontally fast enough 
> to keep missing the Earth and it just keeps falling. This is a visual 
> example of the EP.
>
> LC
>

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Re: Principle of Equivalence



On Sunday, July 12, 2020 at 5:56:21 PM UTC-6, Alan Grayson wrote:
>
>
>
> On Sunday, July 12, 2020 at 4:10:34 PM UTC-6, Lawrence Crowell wrote:
>>
>> On Saturday, July 11, 2020 at 11:00:18 PM UTC-5, Alan Grayson wrote:
>>>
>>>
>>> Can EM waves exist if there are no charges and currents? If you affirm, 
>>> has this ever been observed? This result, if it is a result, is likely an 
>>> artifact of the mathematics which has no basis in physical reality. Anyway, 
>>> are you claiming that spacetime curvature can exist in the absence of 
>>> matter/energy? Is this what the EP says? AG 
>>>
>>
>> Yes they do. A plane or spherical EM wave in a region of space without 
>> charges is an elementary solution to Maxwell's equations.
>>
>> LC 
>>
>
> I don't believe EM waves can exist without charges and/or currents being 
> the source of the waves. Has anyone done an experiment to prove this is 
> possible? Same with gravitational waves existing without the physical 
> presence of mass/energy.  IMO, in both cases, the results of the equations 
> are being misinterpreted. AG
>

What those solutions tell us is that EM waves can travel in regions of 
space without charges and/or currents. They don't tell us that EM waves can 
arise, come into existence, in the absence of charges and/or currents.  AG

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Re: Principle of Equivalence



On Sunday, July 12, 2020 at 4:10:34 PM UTC-6, Lawrence Crowell wrote:
>
> On Saturday, July 11, 2020 at 11:00:18 PM UTC-5, Alan Grayson wrote:
>>
>>
>> Can EM waves exist if there are no charges and currents? If you affirm, 
>> has this ever been observed? This result, if it is a result, is likely an 
>> artifact of the mathematics which has no basis in physical reality. Anyway, 
>> are you claiming that spacetime curvature can exist in the absence of 
>> matter/energy? Is this what the EP says? AG 
>>
>
> Yes they do. A plane or spherical EM wave in a region of space without 
> charges is an elementary solution to Maxwell's equations.
>
> LC 
>

I don't believe EM waves can exist without charges and/or currents being 
the source of the waves. Has anyone done an experiment to prove this is 
possible? Same with gravitational waves existing without the physical 
presence of mass/energy.  IMO, in both cases, the results of the equations 
are being misinterpreted. AG

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Re: Principle of Equivalence

2020-07-12 Thread Lawrence Crowell

I have not followed this thread much. I get the impression there is a lot
of confusion.

The equivalence principle states there is no distinguishing difference
between a frame far away in flat spacetime and one in a region of spacetime
that is curved so long as the frame is small in extent. In other words, it
there is a curvature R and the dimensions of the frame are d then d << √R.
This will mean that any test masses in this small frame will be on
co-parallel geodesics and the local physics is no different than if you are
on a frame in very distant flat spacetime. The converse of this then is
that being on an accelerated frame is indistiguishable from being held
fixed in a gravitational field. The surface of the Earth does that for us.
Then comparing gravity with acceleration this way the implication is that
inertial mass is equal to gravitational mass. The previous case indicates a
way forwards to general relativity with local frames or patches that are
meshed together in a coordinate atlas and transition function that define
connection coefficients and curvature.

Is there a better way to do this, Yes! this is what I have been working on.
Instead of a single small inertial frame consider two frames and in each
there is one of each EPR pair, The easy part is to show that the
entanglement is constant so long as the two frames are on geodesic motion.
This is a sort of extended EP which is potentially useful for quantum
gravitation. This is in particular if spacetime is built up from quantum
entangled states. Things becomes much more difficult when black hole
horizons enter the picture.

The standard EP is not that hard to understand, and in weak gravitation the
obvious example of this are weightless objects and astronauts in spacecraft
and the ISS. In effect this is moving horizontally fast enough to keep
missing the Earth and it just keeps falling. This is a visual example of
the EP.

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Re: Principle of Equivalence

2020-07-12 Thread Lawrence Crowell

On Saturday, July 11, 2020 at 11:00:18 PM UTC-5, Alan Grayson wrote:
>
>
> Can EM waves exist if there are no charges and currents? If you affirm, 
> has this ever been observed? This result, if it is a result, is likely an 
> artifact of the mathematics which has no basis in physical reality. Anyway, 
> are you claiming that spacetime curvature can exist in the absence of 
> matter/energy? Is this what the EP says? AG 
>

Yes they do. A plane or spherical EM wave in a region of space without 
charges is an elementary solution to Maxwell's equations.

LC 

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Re: Principle of Equivalence

2020-07-12 Thread 'Brent Meeker' via Everything List




On 7/12/2020 12:37 AM, Alan Grayson wrote:



On Saturday, July 11, 2020 at 10:30:21 PM UTC-6, Alan Grayson wrote:



On Saturday, July 11, 2020 at 10:20:54 PM UTC-6, Brent wrote:



On 7/11/2020 9:00 PM, Alan Grayson wrote:



On Saturday, July 11, 2020 at 9:49:31 PM UTC-6, Brent wrote:



On 7/11/2020 8:07 PM, Alan Grayson wrote:



On Saturday, July 11, 2020 at 8:41:21 PM UTC-6, Brent
wrote:



On 7/11/2020 4:29 PM, Alan Grayson wrote:



On Saturday, July 11, 2020 at 5:05:02 PM UTC-6,
Brent wrote:



On 7/11/2020 12:54 AM, Alan Grayson wrote:



On Tuesday, July 7, 2020 at 10:06:44 PM UTC-6,
Alan Grayson wrote:



On Tuesday, July 7, 2020 at 8:50:50 PM
UTC-6, Alan Grayson wrote:



On Tuesday, July 7, 2020 at 8:05:28 PM
UTC-6, Bruce wrote:

On Wed, Jul 1, 2020 at 4:18 PM
Alan Grayson 
wrote:

How, exactly, is the Principle
of Equivalence used by
Einstein to develop GR? TIA, AG



This lecture by Sean Carroll
should answer all your questions:

URL: https://wp.me/p2WMeM-3vl

Bruce


I'll watch it tonight, but I think
I've figured it out; specifically, the
EP implies space-time is curved by the
presence of mass/energy (and this is
independent of the need to express the
laws of physics in a coordinate
independent way via tensors). AG


Here's my reasoning regarding the EP; if
an observer is in a box subject to uniform
acceleration, a beam of light starting on
the extreme left side (moving transverse
or perpendicular to the acceleration
vector), will hit a lower point on the
right side, showing that uniform
acceleration results in curved paths in
space-time. But if this result is
identical to gravity, locally, it means
that curved paths in space-time are
produced by, or are equivalent to gravity.



That makes no sense.  You're saying that
because curved paths can be produced two
different ways then they must always be
produced the second way.



BUT gravity is only observed in the
presence of mass/energy. ERGO, the EP
implies mass/energy curves space-time. AG



And that's not even true. Gravitational waves
can propagate thru the vacuum.  The
Schwarzschild solution is for empty space.  De
Sitter space is an empty cosmos.


Light can propagate through empty space, but it
can't arise from nothing. Same presumably for
gravitational waves. AG


Are you going to say the same thing about matter? 
electric charge?

Brent


I'm not sure what your point is. All I was saying above
is that mass/energy causes curvature of space-time as
per the EP. A gravitational wave moving through empty
space seems no different in principle than light moving
through empty space. In both cases there is a
mathematical solution for the wave motion, with the
source of the wave left undefined. But every wave motion
must has a source. AG


And every source must have an origin?  There is nothing
in the equations that says there must be a source.

Brent


Can EM waves exist if there are no charges and currents? If
you affirm, has this ever been observed? This result, if it
is a result, is likely an artifact of the mathematics which
has no basis in physical reality. Anyway, are you claiming
that spacetime curvature can exist in the absence of
matter/energy? Is this what the EP says? AG


It's what the equations say.  So if waves only exist due to
matter sources that's a separate fact, not part of the
theory.  It seems just as plausible to me that fields

Re: Principle of Equivalence



On Saturday, July 11, 2020 at 10:30:21 PM UTC-6, Alan Grayson wrote:
>
>
>
> On Saturday, July 11, 2020 at 10:20:54 PM UTC-6, Brent wrote:
>>
>>
>>
>> On 7/11/2020 9:00 PM, Alan Grayson wrote:
>>
>>
>>
>> On Saturday, July 11, 2020 at 9:49:31 PM UTC-6, Brent wrote: 
>>>
>>>
>>>
>>> On 7/11/2020 8:07 PM, Alan Grayson wrote:
>>>
>>>
>>>
>>> On Saturday, July 11, 2020 at 8:41:21 PM UTC-6, Brent wrote: 
>>>>
>>>>
>>>>
>>>> On 7/11/2020 4:29 PM, Alan Grayson wrote:
>>>>
>>>>
>>>>
>>>> On Saturday, July 11, 2020 at 5:05:02 PM UTC-6, Brent wrote: 
>>>>>
>>>>>
>>>>>
>>>>> On 7/11/2020 12:54 AM, Alan Grayson wrote:
>>>>>
>>>>>
>>>>>
>>>>> On Tuesday, July 7, 2020 at 10:06:44 PM UTC-6, Alan Grayson wrote: 
>>>>>>
>>>>>>
>>>>>>
>>>>>> On Tuesday, July 7, 2020 at 8:50:50 PM UTC-6, Alan Grayson wrote: 
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>> On Tuesday, July 7, 2020 at 8:05:28 PM UTC-6, Bruce wrote: 
>>>>>>>>
>>>>>>>> On Wed, Jul 1, 2020 at 4:18 PM Alan Grayson  
>>>>>>>> wrote:
>>>>>>>>
>>>>>>>>> How, exactly, is the Principle of Equivalence used by Einstein to 
>>>>>>>>> develop GR? TIA, AG
>>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>> This lecture by Sean Carroll should answer all your questions:
>>>>>>>>
>>>>>>>> URL: https://wp.me/p2WMeM-3vl
>>>>>>>>
>>>>>>>> Bruce
>>>>>>>>
>>>>>>>
>>>>>>> I'll watch it tonight, but I think I've figured it out; 
>>>>>>> specifically, the EP implies space-time is curved by the presence of 
>>>>>>> mass/energy (and this is independent of the need to express the laws of 
>>>>>>> physics in a coordinate independent way via tensors). AG
>>>>>>>
>>>>>>
>>>>>> Here's my reasoning regarding the EP; if an observer is in a box 
>>>>>> subject to uniform acceleration, a beam of light starting on the extreme 
>>>>>> left side (moving transverse or perpendicular to the acceleration 
>>>>>> vector), 
>>>>>> will hit a lower point on the right side, showing that uniform 
>>>>>> acceleration 
>>>>>> results in curved paths in space-time. But if this result is identical 
>>>>>> to 
>>>>>> gravity, locally, it means that curved paths in space-time are produced 
>>>>>> by, 
>>>>>> or are equivalent to gravity. 
>>>>>>
>>>>>
>>>>> That makes no sense.  You're saying that because curved paths can be 
>>>>> produced two different ways then they must always be produced the second 
>>>>> way.
>>>>>
>>>>>
>>>>> BUT gravity is only observed in the presence of mass/energy. ERGO, the 
>>>>>> EP implies mass/energy curves space-time. AG 
>>>>>>
>>>>>
>>>>> And that's not even true.  Gravitational waves can propagate thru the 
>>>>> vacuum.  The Schwarzschild solution is for empty space.  De Sitter space 
>>>>> is 
>>>>> an empty cosmos.
>>>>>
>>>>
>>>> Light can propagate through empty space, but it can't arise from 
>>>> nothing. Same presumably for gravitational waves. AG 
>>>>
>>>>
>>>> Are you going to say the same thing about matter?  electric charge?
>>>>
>>>> Brent
>>>>
>>>
>>> I'm not sure what your point is. All I was saying above is that 
>>> mass/energy causes curvature of space-time as per the EP. A gravitational 
>>> wave moving through empty space seems no different in principle than light 
>>> moving through empty space. In both cases there is a mathematical solution 
>>> for the wave motion, with the source of the wave left undefined. But every 
>>> wave motion must has a source. AG
>>>
>

Re: Principle of Equivalence



On Saturday, July 11, 2020 at 10:20:54 PM UTC-6, Brent wrote:
>
>
>
> On 7/11/2020 9:00 PM, Alan Grayson wrote:
>
>
>
> On Saturday, July 11, 2020 at 9:49:31 PM UTC-6, Brent wrote: 
>>
>>
>>
>> On 7/11/2020 8:07 PM, Alan Grayson wrote:
>>
>>
>>
>> On Saturday, July 11, 2020 at 8:41:21 PM UTC-6, Brent wrote: 
>>>
>>>
>>>
>>> On 7/11/2020 4:29 PM, Alan Grayson wrote:
>>>
>>>
>>>
>>> On Saturday, July 11, 2020 at 5:05:02 PM UTC-6, Brent wrote: 
>>>>
>>>>
>>>>
>>>> On 7/11/2020 12:54 AM, Alan Grayson wrote:
>>>>
>>>>
>>>>
>>>> On Tuesday, July 7, 2020 at 10:06:44 PM UTC-6, Alan Grayson wrote: 
>>>>>
>>>>>
>>>>>
>>>>> On Tuesday, July 7, 2020 at 8:50:50 PM UTC-6, Alan Grayson wrote: 
>>>>>>
>>>>>>
>>>>>>
>>>>>> On Tuesday, July 7, 2020 at 8:05:28 PM UTC-6, Bruce wrote: 
>>>>>>>
>>>>>>> On Wed, Jul 1, 2020 at 4:18 PM Alan Grayson  
>>>>>>> wrote:
>>>>>>>
>>>>>>>> How, exactly, is the Principle of Equivalence used by Einstein to 
>>>>>>>> develop GR? TIA, AG
>>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>> This lecture by Sean Carroll should answer all your questions:
>>>>>>>
>>>>>>> URL: https://wp.me/p2WMeM-3vl
>>>>>>>
>>>>>>> Bruce
>>>>>>>
>>>>>>
>>>>>> I'll watch it tonight, but I think I've figured it out; specifically, 
>>>>>> the EP implies space-time is curved by the presence of mass/energy (and 
>>>>>> this is independent of the need to express the laws of physics in a 
>>>>>> coordinate independent way via tensors). AG
>>>>>>
>>>>>
>>>>> Here's my reasoning regarding the EP; if an observer is in a box 
>>>>> subject to uniform acceleration, a beam of light starting on the extreme 
>>>>> left side (moving transverse or perpendicular to the acceleration 
>>>>> vector), 
>>>>> will hit a lower point on the right side, showing that uniform 
>>>>> acceleration 
>>>>> results in curved paths in space-time. But if this result is identical to 
>>>>> gravity, locally, it means that curved paths in space-time are produced 
>>>>> by, 
>>>>> or are equivalent to gravity. 
>>>>>
>>>>
>>>> That makes no sense.  You're saying that because curved paths can be 
>>>> produced two different ways then they must always be produced the second 
>>>> way.
>>>>
>>>>
>>>> BUT gravity is only observed in the presence of mass/energy. ERGO, the 
>>>>> EP implies mass/energy curves space-time. AG 
>>>>>
>>>>
>>>> And that's not even true.  Gravitational waves can propagate thru the 
>>>> vacuum.  The Schwarzschild solution is for empty space.  De Sitter space 
>>>> is 
>>>> an empty cosmos.
>>>>
>>>
>>> Light can propagate through empty space, but it can't arise from 
>>> nothing. Same presumably for gravitational waves. AG 
>>>
>>>
>>> Are you going to say the same thing about matter?  electric charge?
>>>
>>> Brent
>>>
>>
>> I'm not sure what your point is. All I was saying above is that 
>> mass/energy causes curvature of space-time as per the EP. A gravitational 
>> wave moving through empty space seems no different in principle than light 
>> moving through empty space. In both cases there is a mathematical solution 
>> for the wave motion, with the source of the wave left undefined. But every 
>> wave motion must has a source. AG
>>
>>
>> And every source must have an origin?  There is nothing in the equations 
>> that says there must be a source.
>>
>> Brent
>>
>
> Can EM waves exist if there are no charges and currents? If you affirm, 
> has this ever been observed? This result, if it is a result, is likely an 
> artifact of the mathematics which has no basis in physical reality. Anyway, 
> are you claiming that spacetime curvature can exist in the absence of 
> matter/energy? Is this what the EP says? AG 
>
>
> It's what the equations say.  So if waves only exist due to matter sources 
> that's a separate fact, not part of the theory.  It seems just as plausible 
> to me that fields existed first and "stuff" appeared as quantized waves in 
> the fields.  
>
> Brent 
>

What do you find erroneous in my interpretation of the EP? I never heard it 
interpreted to mean that curvature of space-time is NOT caused by gravity. 
AG 

>
>
>
> -- 
> You received this message because you are subscribed to the Google Groups 
> "Everything List" group.
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> email to everyth...@googlegroups.com .
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>  
> <https://groups.google.com/d/msgid/everything-list/3372804f-6bf6-44d4-9506-f73bf607e6e6o%40googlegroups.com?utm_medium=email_source=footer>
> .
>
>
>

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Re: Principle of Equivalence

2020-07-11 Thread 'Brent Meeker' via Everything List

On 7/11/2020 9:00 PM, Alan Grayson wrote:

On Saturday, July 11, 2020 at 9:49:31 PM UTC-6, Brent wrote:

On 7/11/2020 8:07 PM, Alan Grayson wrote:

On Saturday, July 11, 2020 at 8:41:21 PM UTC-6, Brent wrote:

On 7/11/2020 4:29 PM, Alan Grayson wrote:

On Saturday, July 11, 2020 at 5:05:02 PM UTC-6, Brent wrote:

On 7/11/2020 12:54 AM, Alan Grayson wrote:

On Tuesday, July 7, 2020 at 10:06:44 PM UTC-6, Alan
Grayson wrote:

On Tuesday, July 7, 2020 at 8:50:50 PM UTC-6, Alan
Grayson wrote:

On Tuesday, July 7, 2020 at 8:05:28 PM UTC-6,
Bruce wrote:

On Wed, Jul 1, 2020 at 4:18 PM Alan Grayson
wrote:

How, exactly, is the Principle of
Equivalence used by Einstein to develop
GR? TIA, AG

This lecture by Sean Carroll should answer
all your questions:

URL: https://wp.me/p2WMeM-3vl

Bruce

I'll watch it tonight, but I think I've figured
it out; specifically, the EP implies space-time
is curved by the presence of mass/energy (and
this is independent of the need to express the
laws of physics in a coordinate independent way
via tensors). AG

Here's my reasoning regarding the EP; if an
observer is in a box subject to uniform
acceleration, a beam of light starting on the
extreme left side (moving transverse or
perpendicular to the acceleration vector), will hit
a lower point on the right side, showing that
uniform acceleration results in curved paths in
space-time. But if this result is identical to
gravity, locally, it means that curved paths in
space-time are produced by, or are equivalent to
gravity.

That makes no sense. You're saying that because curved
paths can be produced two different ways then they must
always be produced the second way.

BUT gravity is only observed in the presence of
mass/energy. ERGO, the EP implies mass/energy
curves space-time. AG

And that's not even true. Gravitational waves can
propagate thru the vacuum. The Schwarzschild solution
is for empty space. De Sitter space is an empty cosmos.

Light can propagate through empty space, but it can't arise
from nothing. Same presumably for gravitational waves. AG

Are you going to say the same thing about matter? electric
charge?

Brent

I'm not sure what your point is. All I was saying above is that
mass/energy causes curvature of space-time as per the EP. A
gravitational wave moving through empty space seems no different
in principle than light moving through empty space. In both cases
there is a mathematical solution for the wave motion, with the
source of the wave left undefined. But every wave motion must has
a source. AG

And every source must have an origin? There is nothing in the
equations that says there must be a source.

Brent

Can EM waves exist if there are no charges and currents? If you
affirm, has this ever been observed? This result, if it is a result,
is likely an artifact of the mathematics which has no basis in
physical reality. Anyway, are you claiming that spacetime curvature
can exist in the absence of matter/energy? Is this what the EP says? AG

It's what the equations say. So if waves only exist due to matter
sources that's a separate fact, not part of the theory. It seems just
as plausible to me that fields existed first and "stuff" appeared as
quantized waves in the fields.

Brent

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Re: Principle of Equivalence



On Saturday, July 11, 2020 at 9:49:31 PM UTC-6, Brent wrote:
>
>
>
> On 7/11/2020 8:07 PM, Alan Grayson wrote:
>
>
>
> On Saturday, July 11, 2020 at 8:41:21 PM UTC-6, Brent wrote: 
>>
>>
>>
>> On 7/11/2020 4:29 PM, Alan Grayson wrote:
>>
>>
>>
>> On Saturday, July 11, 2020 at 5:05:02 PM UTC-6, Brent wrote: 
>>>
>>>
>>>
>>> On 7/11/2020 12:54 AM, Alan Grayson wrote:
>>>
>>>
>>>
>>> On Tuesday, July 7, 2020 at 10:06:44 PM UTC-6, Alan Grayson wrote: 
>>>>
>>>>
>>>>
>>>> On Tuesday, July 7, 2020 at 8:50:50 PM UTC-6, Alan Grayson wrote: 
>>>>>
>>>>>
>>>>>
>>>>> On Tuesday, July 7, 2020 at 8:05:28 PM UTC-6, Bruce wrote: 
>>>>>>
>>>>>> On Wed, Jul 1, 2020 at 4:18 PM Alan Grayson  
>>>>>> wrote:
>>>>>>
>>>>>>> How, exactly, is the Principle of Equivalence used by Einstein to 
>>>>>>> develop GR? TIA, AG
>>>>>>>
>>>>>>
>>>>>>
>>>>>> This lecture by Sean Carroll should answer all your questions:
>>>>>>
>>>>>> URL: https://wp.me/p2WMeM-3vl
>>>>>>
>>>>>> Bruce
>>>>>>
>>>>>
>>>>> I'll watch it tonight, but I think I've figured it out; specifically, 
>>>>> the EP implies space-time is curved by the presence of mass/energy (and 
>>>>> this is independent of the need to express the laws of physics in a 
>>>>> coordinate independent way via tensors). AG
>>>>>
>>>>
>>>> Here's my reasoning regarding the EP; if an observer is in a box 
>>>> subject to uniform acceleration, a beam of light starting on the extreme 
>>>> left side (moving transverse or perpendicular to the acceleration vector), 
>>>> will hit a lower point on the right side, showing that uniform 
>>>> acceleration 
>>>> results in curved paths in space-time. But if this result is identical to 
>>>> gravity, locally, it means that curved paths in space-time are produced 
>>>> by, 
>>>> or are equivalent to gravity. 
>>>>
>>>
>>> That makes no sense.  You're saying that because curved paths can be 
>>> produced two different ways then they must always be produced the second 
>>> way.
>>>
>>>
>>> BUT gravity is only observed in the presence of mass/energy. ERGO, the 
>>>> EP implies mass/energy curves space-time. AG 
>>>>
>>>
>>> And that's not even true.  Gravitational waves can propagate thru the 
>>> vacuum.  The Schwarzschild solution is for empty space.  De Sitter space is 
>>> an empty cosmos.
>>>
>>
>> Light can propagate through empty space, but it can't arise from nothing. 
>> Same presumably for gravitational waves. AG 
>>
>>
>> Are you going to say the same thing about matter?  electric charge?
>>
>> Brent
>>
>
> I'm not sure what your point is. All I was saying above is that 
> mass/energy causes curvature of space-time as per the EP. A gravitational 
> wave moving through empty space seems no different in principle than light 
> moving through empty space. In both cases there is a mathematical solution 
> for the wave motion, with the source of the wave left undefined. But every 
> wave motion must has a source. AG
>
>
> And every source must have an origin?  There is nothing in the equations 
> that says there must be a source.
>
> Brent
>

Can EM waves exist if there are no charges and currents? If you affirm, has 
this ever been observed? This result, if it is a result, is likely an 
artifact of the mathematics which has no basis in physical reality. Anyway, 
are you claiming that spacetime curvature can exist in the absence of 
matter/energy? Is this what the EP says? AG 

-- 
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Re: Principle of Equivalence

2020-07-11 Thread 'Brent Meeker' via Everything List

On 7/11/2020 8:07 PM, Alan Grayson wrote:

On Saturday, July 11, 2020 at 8:41:21 PM UTC-6, Brent wrote:

On 7/11/2020 4:29 PM, Alan Grayson wrote:

On Saturday, July 11, 2020 at 5:05:02 PM UTC-6, Brent wrote:

On 7/11/2020 12:54 AM, Alan Grayson wrote:

On Tuesday, July 7, 2020 at 10:06:44 PM UTC-6, Alan Grayson
wrote:

On Tuesday, July 7, 2020 at 8:50:50 PM UTC-6, Alan
Grayson wrote:

On Tuesday, July 7, 2020 at 8:05:28 PM UTC-6, Bruce
wrote:

On Wed, Jul 1, 2020 at 4:18 PM Alan Grayson
wrote:

How, exactly, is the Principle of
Equivalence used by Einstein to develop GR?
TIA, AG

This lecture by Sean Carroll should answer all
your questions:

URL: https://wp.me/p2WMeM-3vl

Bruce

I'll watch it tonight, but I think I've figured it
out; specifically, the EP implies space-time is
curved by the presence of mass/energy (and this is
independent of the need to express the laws of
physics in a coordinate independent way via tensors). AG

Here's my reasoning regarding the EP; if an observer is
in a box subject to uniform acceleration, a beam of
light starting on the extreme left side (moving
transverse or perpendicular to the acceleration vector),
will hit a lower point on the right side, showing that
uniform acceleration results in curved paths in
space-time. But if this result is identical to gravity,
locally, it means that curved paths in space-time are
produced by, or are equivalent to gravity.

That makes no sense. You're saying that because curved paths
can be produced two different ways then they must always be
produced the second way.

BUT gravity is only observed in the presence of
mass/energy. ERGO, the EP implies mass/energy curves
space-time. AG

And that's not even true. Gravitational waves can propagate
thru the vacuum. The Schwarzschild solution is for empty
space. De Sitter space is an empty cosmos.

Light can propagate through empty space, but it can't arise from
nothing. Same presumably for gravitational waves. AG

Are you going to say the same thing about matter? electric charge?

Brent

I'm not sure what your point is. All I was saying above is that
mass/energy causes curvature of space-time as per the EP. A
gravitational wave moving through empty space seems no different in
principle than light moving through empty space. In both cases there
is a mathematical solution for the wave motion, with the source of the
wave left undefined. But every wave motion must has a source. AG

And every source must have an origin? There is nothing in the equations
that says there must be a source.

Brent

--
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Re: Principle of Equivalence



On Saturday, July 11, 2020 at 8:41:21 PM UTC-6, Brent wrote:
>
>
>
> On 7/11/2020 4:29 PM, Alan Grayson wrote:
>
>
>
> On Saturday, July 11, 2020 at 5:05:02 PM UTC-6, Brent wrote: 
>>
>>
>>
>> On 7/11/2020 12:54 AM, Alan Grayson wrote:
>>
>>
>>
>> On Tuesday, July 7, 2020 at 10:06:44 PM UTC-6, Alan Grayson wrote: 
>>>
>>>
>>>
>>> On Tuesday, July 7, 2020 at 8:50:50 PM UTC-6, Alan Grayson wrote: 
>>>>
>>>>
>>>>
>>>> On Tuesday, July 7, 2020 at 8:05:28 PM UTC-6, Bruce wrote: 
>>>>>
>>>>> On Wed, Jul 1, 2020 at 4:18 PM Alan Grayson  
>>>>> wrote:
>>>>>
>>>>>> How, exactly, is the Principle of Equivalence used by Einstein to 
>>>>>> develop GR? TIA, AG
>>>>>>
>>>>>
>>>>>
>>>>> This lecture by Sean Carroll should answer all your questions:
>>>>>
>>>>> URL: https://wp.me/p2WMeM-3vl
>>>>>
>>>>> Bruce
>>>>>
>>>>
>>>> I'll watch it tonight, but I think I've figured it out; specifically, 
>>>> the EP implies space-time is curved by the presence of mass/energy (and 
>>>> this is independent of the need to express the laws of physics in a 
>>>> coordinate independent way via tensors). AG
>>>>
>>>
>>> Here's my reasoning regarding the EP; if an observer is in a box subject 
>>> to uniform acceleration, a beam of light starting on the extreme left side 
>>> (moving transverse or perpendicular to the acceleration vector), will hit a 
>>> lower point on the right side, showing that uniform acceleration results in 
>>> curved paths in space-time. But if this result is identical to gravity, 
>>> locally, it means that curved paths in space-time are produced by, or are 
>>> equivalent to gravity. 
>>>
>>
>> That makes no sense.  You're saying that because curved paths can be 
>> produced two different ways then they must always be produced the second 
>> way.
>>
>>
>> BUT gravity is only observed in the presence of mass/energy. ERGO, the EP 
>>> implies mass/energy curves space-time. AG 
>>>
>>
>> And that's not even true.  Gravitational waves can propagate thru the 
>> vacuum.  The Schwarzschild solution is for empty space.  De Sitter space is 
>> an empty cosmos.
>>
>
> Light can propagate through empty space, but it can't arise from nothing. 
> Same presumably for gravitational waves. AG 
>
>
> Are you going to say the same thing about matter?  electric charge?
>
> Brent
>

I'm not sure what your point is. All I was saying above is that mass/energy 
causes curvature of space-time as per the EP. A gravitational wave moving 
through empty space seems no different in principle than light moving 
through empty space. In both cases there is a mathematical solution for the 
wave motion, with the source of the wave left undefined. But every wave 
motion must has a source. AG

-- 
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"Everything List" group.
To unsubscribe from this group and stop receiving emails from it, send an email 
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Re: Principle of Equivalence

2020-07-11 Thread 'Brent Meeker' via Everything List

On 7/11/2020 4:29 PM, Alan Grayson wrote:

On Saturday, July 11, 2020 at 5:05:02 PM UTC-6, Brent wrote:

On 7/11/2020 12:54 AM, Alan Grayson wrote:

On Tuesday, July 7, 2020 at 10:06:44 PM UTC-6, Alan Grayson wrote:

On Tuesday, July 7, 2020 at 8:50:50 PM UTC-6, Alan Grayson
wrote:

On Tuesday, July 7, 2020 at 8:05:28 PM UTC-6, Bruce wrote:

On Wed, Jul 1, 2020 at 4:18 PM Alan Grayson
wrote:

How, exactly, is the Principle of Equivalence
used by Einstein to develop GR? TIA, AG

This lecture by Sean Carroll should answer all your
questions:

URL: https://wp.me/p2WMeM-3vl

Bruce

I'll watch it tonight, but I think I've figured it out;
specifically, the EP implies space-time is curved by the
presence of mass/energy (and this is independent of the
need to express the laws of physics in a coordinate
independent way via tensors). AG

Here's my reasoning regarding the EP; if an observer is in a
box subject to uniform acceleration, a beam of light starting
on the extreme left side (moving transverse or perpendicular
to the acceleration vector), will hit a lower point on the
right side, showing that uniform acceleration results in
curved paths in space-time. But if this result is identical
to gravity, locally, it means that curved paths in space-time
are produced by, or are equivalent to gravity.

That makes no sense. You're saying that because curved paths can
be produced two different ways then they must always be produced
the second way.

BUT gravity is only observed in the presence of mass/energy.
ERGO, the EP implies mass/energy curves space-time. AG

And that's not even true. Gravitational waves can propagate thru
the vacuum. The Schwarzschild solution is for empty space. De
Sitter space is an empty cosmos.

Light can propagate through empty space, but it can't arise from
nothing. Same presumably for gravitational waves. AG

Are you going to say the same thing about matter? electric charge?

Brent

--
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Re: Principle of Equivalence



On Saturday, July 11, 2020 at 5:29:03 PM UTC-6, Alan Grayson wrote:
>
>
>
> On Saturday, July 11, 2020 at 5:05:02 PM UTC-6, Brent wrote:
>>
>>
>>
>> On 7/11/2020 12:54 AM, Alan Grayson wrote:
>>
>>
>>
>> On Tuesday, July 7, 2020 at 10:06:44 PM UTC-6, Alan Grayson wrote: 
>>>
>>>
>>>
>>> On Tuesday, July 7, 2020 at 8:50:50 PM UTC-6, Alan Grayson wrote: 
>>>>
>>>>
>>>>
>>>> On Tuesday, July 7, 2020 at 8:05:28 PM UTC-6, Bruce wrote: 
>>>>>
>>>>> On Wed, Jul 1, 2020 at 4:18 PM Alan Grayson  
>>>>> wrote:
>>>>>
>>>>>> How, exactly, is the Principle of Equivalence used by Einstein to 
>>>>>> develop GR? TIA, AG
>>>>>>
>>>>>
>>>>>
>>>>> This lecture by Sean Carroll should answer all your questions:
>>>>>
>>>>> URL: https://wp.me/p2WMeM-3vl
>>>>>
>>>>> Bruce
>>>>>
>>>>
>>>> I'll watch it tonight, but I think I've figured it out; specifically, 
>>>> the EP implies space-time is curved by the presence of mass/energy (and 
>>>> this is independent of the need to express the laws of physics in a 
>>>> coordinate independent way via tensors). AG
>>>>
>>>
>>> Here's my reasoning regarding the EP; if an observer is in a box subject 
>>> to uniform acceleration, a beam of light starting on the extreme left side 
>>> (moving transverse or perpendicular to the acceleration vector), will hit a 
>>> lower point on the right side, showing that uniform acceleration results in 
>>> curved paths in space-time. But if this result is identical to gravity, 
>>> locally, it means that curved paths in space-time are produced by, or are 
>>> equivalent to gravity. 
>>>
>>
>> That makes no sense.  You're saying that because curved paths can be 
>> produced two different ways then they must always be produced the second 
>> way.
>>
>>
>> BUT gravity is only observed in the presence of mass/energy. ERGO, the EP 
>>> implies mass/energy curves space-time. AG 
>>>
>>
>> And that's not even true.  Gravitational waves can propagate thru the 
>> vacuum.  The Schwarzschild solution is for empty space.  De Sitter space is 
>> an empty cosmos.
>>
>
> Light can propagate through empty space, but it can't arise from nothing. 
> Same presumably for gravitational waves. AG 
>

In a universe with no matter or energy, aren't we back to SR where there's 
no curvature and light travels in a straight line? So the gravitational 
waves you refer to don't take curved paths. AG
 

>
>> Brent
>>
>>
>> For Bruce; so far I've gotten about two-thirds through Carroll's video. 
>> Will complete it this weekend. I sense a flaw in GR, suggested by the 
>> inclusion of G, the gravitational constant. How can a constant inferred 
>> from an approximate theory of gravity, Newton's Theory of Gravitation, be 
>> included in a presumed perfect theory of gravity, General Relativity? Don't 
>> you think something very subtle is awry here? AG
>> -- 
>> You received this message because you are subscribed to the Google Groups 
>> "Everything List" group.
>> To unsubscribe from this group and stop receiving emails from it, send an 
>> email to everyth...@googlegroups.com.
>> To view this discussion on the web visit 
>> https://groups.google.com/d/msgid/everything-list/ffbbc9e9-1ba7-4410-8009-d76cf4ec12e6o%40googlegroups.com
>>  
>> <https://groups.google.com/d/msgid/everything-list/ffbbc9e9-1ba7-4410-8009-d76cf4ec12e6o%40googlegroups.com?utm_medium=email_source=footer>
>> .
>>
>>
>>

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Re: Principle of Equivalence



On Saturday, July 11, 2020 at 5:05:02 PM UTC-6, Brent wrote:
>
>
>
> On 7/11/2020 12:54 AM, Alan Grayson wrote:
>
>
>
> On Tuesday, July 7, 2020 at 10:06:44 PM UTC-6, Alan Grayson wrote: 
>>
>>
>>
>> On Tuesday, July 7, 2020 at 8:50:50 PM UTC-6, Alan Grayson wrote: 
>>>
>>>
>>>
>>> On Tuesday, July 7, 2020 at 8:05:28 PM UTC-6, Bruce wrote: 
>>>>
>>>> On Wed, Jul 1, 2020 at 4:18 PM Alan Grayson  
>>>> wrote:
>>>>
>>>>> How, exactly, is the Principle of Equivalence used by Einstein to 
>>>>> develop GR? TIA, AG
>>>>>
>>>>
>>>>
>>>> This lecture by Sean Carroll should answer all your questions:
>>>>
>>>> URL: https://wp.me/p2WMeM-3vl
>>>>
>>>> Bruce
>>>>
>>>
>>> I'll watch it tonight, but I think I've figured it out; specifically, 
>>> the EP implies space-time is curved by the presence of mass/energy (and 
>>> this is independent of the need to express the laws of physics in a 
>>> coordinate independent way via tensors). AG
>>>
>>
>> Here's my reasoning regarding the EP; if an observer is in a box subject 
>> to uniform acceleration, a beam of light starting on the extreme left side 
>> (moving transverse or perpendicular to the acceleration vector), will hit a 
>> lower point on the right side, showing that uniform acceleration results in 
>> curved paths in space-time. But if this result is identical to gravity, 
>> locally, it means that curved paths in space-time are produced by, or are 
>> equivalent to gravity. 
>>
>
> That makes no sense.  You're saying that because curved paths can be 
> produced two different ways then they must always be produced the second 
> way.
>
>
> BUT gravity is only observed in the presence of mass/energy. ERGO, the EP 
>> implies mass/energy curves space-time. AG 
>>
>
> And that's not even true.  Gravitational waves can propagate thru the 
> vacuum.  The Schwarzschild solution is for empty space.  De Sitter space is 
> an empty cosmos.
>

Light can propagate through empty space, but it can't arise from nothing. 
Same presumably for gravitational waves. AG 

>
> Brent
>
>
> For Bruce; so far I've gotten about two-thirds through Carroll's video. 
> Will complete it this weekend. I sense a flaw in GR, suggested by the 
> inclusion of G, the gravitational constant. How can a constant inferred 
> from an approximate theory of gravity, Newton's Theory of Gravitation, be 
> included in a presumed perfect theory of gravity, General Relativity? Don't 
> you think something very subtle is awry here? AG
> -- 
> You received this message because you are subscribed to the Google Groups 
> "Everything List" group.
> To unsubscribe from this group and stop receiving emails from it, send an 
> email to everyth...@googlegroups.com .
> To view this discussion on the web visit 
> https://groups.google.com/d/msgid/everything-list/ffbbc9e9-1ba7-4410-8009-d76cf4ec12e6o%40googlegroups.com
>  
> <https://groups.google.com/d/msgid/everything-list/ffbbc9e9-1ba7-4410-8009-d76cf4ec12e6o%40googlegroups.com?utm_medium=email_source=footer>
> .
>
>
>

-- 
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Re: Principle of Equivalence

2020-07-11 Thread 'Brent Meeker' via Everything List

On 7/11/2020 12:54 AM, Alan Grayson wrote:

On Tuesday, July 7, 2020 at 10:06:44 PM UTC-6, Alan Grayson wrote:

On Tuesday, July 7, 2020 at 8:50:50 PM UTC-6, Alan Grayson wrote:

On Tuesday, July 7, 2020 at 8:05:28 PM UTC-6, Bruce wrote:

On Wed, Jul 1, 2020 at 4:18 PM Alan Grayson
wrote:

How, exactly, is the Principle of Equivalence used by
Einstein to develop GR? TIA, AG

This lecture by Sean Carroll should answer all your questions:

URL: https://wp.me/p2WMeM-3vl

Bruce

I'll watch it tonight, but I think I've figured it out;
specifically, the EP implies space-time is curved by the
presence of mass/energy (and this is independent of the need
to express the laws of physics in a coordinate independent way
via tensors). AG

Here's my reasoning regarding the EP; if an observer is in a box
subject to uniform acceleration, a beam of light starting on the
extreme left side (moving transverse or perpendicular to the
acceleration vector), will hit a lower point on the right side,
showing that uniform acceleration results in curved paths in
space-time. But if this result is identical to gravity, locally,
it means that curved paths in space-time are produced by, or are
equivalent to gravity.

That makes no sense. You're saying that because curved paths can be
produced two different ways then they must always be produced the second
way.

BUT gravity is only observed in the presence of mass/energy. ERGO,
the EP implies mass/energy curves space-time. AG

And that's not even true. Gravitational waves can propagate thru the
vacuum. The Schwarzschild solution is for empty space. De Sitter space
is an empty cosmos.

Brent

For Bruce; so far I've gotten about two-thirds through Carroll's
video. Will complete it this weekend. I sense a flaw in GR, suggested
by the inclusion of G, the gravitational constant. How can a constant
inferred from an approximate theory of gravity, Newton's Theory of
Gravitation, be included in a presumed perfect theory of gravity,
General Relativity? Don't you think something very subtle is awry here? AG

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Re: Principle of Equivalence



On Saturday, July 11, 2020 at 1:37:48 PM UTC-6, John Clark wrote:
>
> On Sat, Jul 11, 2020 at 3:54 AM Alan Grayson  > wrote:
>
> *> I sense a flaw in GR*
>
>
> I'll inform the Nobel Prize committee. Your gold medal should be arriving 
> by UPS any day now.
>
>  John K Clark 
>

We know it's not a perfect theory. No theory is. Do you know how G got 
included, or as a Trumper do you prefer to BS? AG 

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Re: Principle of Equivalence

2020-07-11 Thread John Clark

On Sat, Jul 11, 2020 at 3:54 AM Alan Grayson  wrote:

*> I sense a flaw in GR*


I'll inform the Nobel Prize committee. Your gold medal should be arriving
by UPS any day now.

 John K Clark

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Re: Principle of Equivalence



On Tuesday, July 7, 2020 at 10:06:44 PM UTC-6, Alan Grayson wrote:
>
>
>
> On Tuesday, July 7, 2020 at 8:50:50 PM UTC-6, Alan Grayson wrote:
>>
>>
>>
>> On Tuesday, July 7, 2020 at 8:05:28 PM UTC-6, Bruce wrote:
>>>
>>> On Wed, Jul 1, 2020 at 4:18 PM Alan Grayson  wrote:
>>>
>>>> How, exactly, is the Principle of Equivalence used by Einstein to 
>>>> develop GR? TIA, AG
>>>>
>>>
>>>
>>> This lecture by Sean Carroll should answer all your questions:
>>>
>>> URL: https://wp.me/p2WMeM-3vl
>>>
>>> Bruce
>>>
>>
>> I'll watch it tonight, but I think I've figured it out; specifically, the 
>> EP implies space-time is curved by the presence of mass/energy (and this is 
>> independent of the need to express the laws of physics in a coordinate 
>> independent way via tensors). AG
>>
>
> Here's my reasoning regarding the EP; if an observer is in a box subject 
> to uniform acceleration, a beam of light starting on the extreme left side 
> (moving transverse or perpendicular to the acceleration vector), will hit a 
> lower point on the right side, showing that uniform acceleration results in 
> curved paths in space-time. But if this result is identical to gravity, 
> locally, it means that curved paths in space-time are produced by, or are 
> equivalent to gravity. BUT gravity is only observed in the presence of 
> mass/energy. ERGO, the EP implies mass/energy curves space-time. AG 
>

For Bruce; so far I've gotten about two-thirds through Carroll's video. 
Will complete it this weekend. I sense a flaw in GR, suggested by the 
inclusion of G, the gravitational constant. How can a constant inferred 
from an approximate theory of gravity, Newton's Theory of Gravitation, be 
included in a presumed perfect theory of gravity, General Relativity? Don't 
you think something very subtle is awry here? AG

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Re: Principle of Equivalence

2020-07-07 Thread Alan Grayson

On Tuesday, July 7, 2020 at 8:50:50 PM UTC-6, Alan Grayson wrote:
>
>
>
> On Tuesday, July 7, 2020 at 8:05:28 PM UTC-6, Bruce wrote:
>>
>> On Wed, Jul 1, 2020 at 4:18 PM Alan Grayson  wrote:
>>
>>> How, exactly, is the Principle of Equivalence used by Einstein to 
>>> develop GR? TIA, AG
>>>
>>
>>
>> This lecture by Sean Carroll should answer all your questions:
>>
>> URL: https://wp.me/p2WMeM-3vl
>>
>> Bruce
>>
>
> I'll watch it tonight, but I think I've figured it out; specifically, the 
> EP implies space-time is curved by the presence of mass/energy (and this is 
> independent of the need to express the laws of physics in a coordinate 
> independent way via tensors). AG
>

Here's my reasoning regarding the EP; if an observer is in a box subject to 
uniform acceleration, a beam of light starting on the extreme left side 
(moving transverse or perpendicular to the acceleration vector), will hit a 
lower point on the right side, showing that uniform acceleration results in 
curved paths in space-time. But if this result is identical to gravity, 
locally, it means that curved paths in space-time are produced by, or are 
equivalent to gravity. BUT gravity is only observed in the presence of 
mass/energy. ERGO, the EP implies mass/energy curves space-time. AG 

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Re: Principle of Equivalence

2020-07-07 Thread Alan Grayson



On Tuesday, July 7, 2020 at 8:05:28 PM UTC-6, Bruce wrote:
>
> On Wed, Jul 1, 2020 at 4:18 PM Alan Grayson  > wrote:
>
>> How, exactly, is the Principle of Equivalence used by Einstein to develop 
>> GR? TIA, AG
>>
>
>
> This lecture by Sean Carroll should answer all your questions:
>
> URL: https://wp.me/p2WMeM-3vl
>
> Bruce
>

I'll watch it tonight, but I think I've figured it out; specifically, the 
EP implies space-time is curved by the presence of mass/energy (and this is 
independent of the need to express the laws of physics in a coordinate 
independent way via tensors). AG

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Re: Principle of Equivalence

2020-07-07 Thread Bruce Kellett

On Wed, Jul 1, 2020 at 4:18 PM Alan Grayson  wrote:

> How, exactly, is the Principle of Equivalence used by Einstein to develop
> GR? TIA, AG
>


This lecture by Sean Carroll should answer all your questions:

URL: https://wp.me/p2WMeM-3vl

Bruce

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Re: Principle of Equivalence

2020-07-06 Thread Alan Grayson

On Monday, July 6, 2020 at 5:29:51 AM UTC-6, John Clark wrote:
>
> On Mon, Jul 6, 2020 at 2:36 AM Alan Grayson  > wrote:
>
> *> For laws of physics to exist, they must be independent of coordinate 
>> system.*
>
>
> That statement *IS* the Equivalence Principle, 
>

In every text that I've seen the EP is specifically related to gravity, and 
for good reason; namely, it is conditioned by "locally". In a gravitational 
field, two bodies allowed to fall free, do NOT take parallel paths. Each 
falls to the center of mass of the gravitating body. My statement above is 
NOT the EP.  It's a general statement of the requirements of a law of 
physics. AG 

> it's just using different language, and Einstein passionately thought it 
> was true, but there were some instances where it didn't seem to be. For 
> example, if there was no limit on how fast you could move and the speed of 
> causality was infinite then you could move at the speed of light alongside 
> a light beam and if you looked at the light beam you would see that it 
> consisted of a unmoving standing wave of electric and magnetic fields; but 
> that's *NOT* what Maxwell's equations says it should ever look like. So 
> Maxwell's equation, a very important law of physics, would NOT be 
> independent of the coordinate system.
>

Before Einstein's 1905 paper, it was known that ME's are invariant under 
the LT. They predicted c for the SoL, but didn't specifically indicate in 
which coordinate system this would be true. They suggested it would be true 
in ANY coordinate system, and gave Einstein a clue about the invariance of 
the SoL for SR. AG

>
> Einstein was just about the only one who was bothered by this and so he 
> worked on the problem and in 1905 he found the solution, at least for 
> Maxwell's equations, he found a way to make them true regardless of the 
> coordinate system. 
>

As previously stated, before 1905 it was known that ME's are invariant 
under the LT. In his 1905 paper, Einstein didn't modify ME's; he just 
modified Newtonian mechanics to make mechanics invariant under the LT. AG 

But doing the same thing for gravity was far far more difficult, he 
> concentrated on the problem for 10 years after that so hard he got sick, 
> lost 60 pounds and nearly died, but eventually he found a tensor to 
> describe how objects move through space-time and a tensor to describe how 
> mass curved space-time. And so with those tensors gravity became 
> independent of the coordinate system too
>
> *> I don't see what the EP has to do with this, *
>
>
> I do.
>
>  John K Clark
>

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Re: Principle of Equivalence

2020-07-06 Thread John Clark

On Mon, Jul 6, 2020 at 2:36 AM Alan Grayson  wrote:

*> For laws of physics to exist, they must be independent of coordinate
> system.*


That statement *IS* the Equivalence Principle, it's just using different
language, and Einstein passionately thought it was true, but there were
some instances where it didn't seem to be. For example, if there was no
limit on how fast you could move and the speed of causality was infinite
then you could move at the speed of light alongside a light beam and if you
looked at the light beam you would see that it consisted of a unmoving
standing wave of electric and magnetic fields; but that's *NOT* what
Maxwell's equations says it should ever look like. So Maxwell's equation, a
very important law of physics, would NOT be independent of the coordinate
system.

Einstein was just about the only one who was bothered by this and so he
worked on the problem and in 1905 he found the solution, at least for
Maxwell's equations, he found a way to make them true regardless of the
coordinate system. But doing the same thing for gravity was far far more
difficult, he concentrated on the problem for 10 years after that so hard
he got sick, lost 60 pounds and nearly died, but eventually he found a
tensor to describe how objects move through space-time and a tensor to
describe how mass curved space-time. And so with those tensors gravity
became independent of the coordinate system too

*> I don't see what the EP has to do with this, *


I do.

 John K Clark

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Re: Principle of Equivalence

2020-07-06 Thread Alan Grayson



On Sunday, July 5, 2020 at 10:59:57 AM UTC-6, Alan Grayson wrote:
>
>
>
> On Sunday, July 5, 2020 at 10:02:52 AM UTC-6, John Clark wrote:
>>
>> On Sat, Jul 4, 2020 at 10:55 AM Alan Grayson  wrote:
>>
>> > *tensors are inherently independent of coordinate systems*
>>
>>
>> Yes exactly, but it's not easy to find a tensor that correctly describes 
>> how objects move through spacetime, and its far from obvious that such a 
>> tensor even exists, but it does and Einstein managed to find it. And that's 
>> why he's so famous.
>>
>> > *What has this to do with the Equivalence Principle?*
>>
>>
>> Alan you just said "tensors are inherently independent of coordinate 
>> systems" what is it that you think "The Equivalence Principle" means?
>>
>>  John K Clark
>>
>
> I stated it earlier. The EP means gravity is locally indistinguishable 
> from acceleration. How does one get from this insight, to 
> "indistinguishable from coordinate system"? The latter is always true, must 
> be true, if laws of physics are to exist. AG 
>

Do you see my point? For laws of physics to exist, they must be independent 
of coordinate system. I don't see what the EP has to do with this, or how 
Einstein used it to formulate GR. AG 

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Re: Principle of Equivalence

2020-07-05 Thread Alan Grayson



On Sunday, July 5, 2020 at 10:02:52 AM UTC-6, John Clark wrote:
>
> On Sat, Jul 4, 2020 at 10:55 AM Alan Grayson  > wrote:
>
> > *tensors are inherently independent of coordinate systems*
>
>
> Yes exactly, but it's not easy to find a tensor that correctly describes 
> how objects move through spacetime, and its far from obvious that such a 
> tensor even exists, but it does and Einstein managed to find it. And that's 
> why he's so famous.
>
> > *What has this to do with the Equivalence Principle?*
>
>
> Alan you just said "tensors are inherently independent of coordinate 
> systems" what is it that you think "The Equivalence Principle" means?
>
>  John K Clark
>

I stated it earlier. The EP means gravity is locally indistinguishable from 
acceleration. How does one get from this insight, to "indistinguishable 
from coordinate system"? The latter is always true, must be true, if laws 
of physics are to exist. AG 

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Re: Principle of Equivalence

2020-07-05 Thread John Clark

On Sat, Jul 4, 2020 at 10:55 AM Alan Grayson  wrote:

> *tensors are inherently independent of coordinate systems*

Yes exactly, but it's not easy to find a tensor that correctly describes
how objects move through spacetime, and its far from obvious that such a
tensor even exists, but it does and Einstein managed to find it. And that's
why he's so famous.

> *What has this to do with the Equivalence Principle?*

Alan you just said "tensors are inherently independent of coordinate
systems" what is it that you think "The Equivalence Principle" means?

 John K Clark

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Re: Principle of Equivalence

2020-07-04 Thread Alan Grayson



On Saturday, July 4, 2020 at 7:51:04 AM UTC-6, John Clark wrote:
>
> On Fri, Jul 3, 2020 at 8:41 PM Alan Grayson  > wrote:
>
> *> Supposedly, the EP gave Einstein his key insight for GR, but his 
>> November 1915 doesn't reference it, not once! AG*
>>
>
> Einstein didn't need to spell it out because he found a tensor to describe 
> how things move through spacetime, and tensors by their very mathematical 
> nature are frame indifferent, if a tensor works in one reference frame it 
> will work in any reference frame. And in scientific papers it's not 
> customary to give a history of the evolution of your thought process or 
> anecdotes about how you happen to come up with your idea, you just state 
> your idea and then make suggestions about how it could be tested.
>
>  John K Clark
>

*I generally agree with your comment about the style of scientific papers 
even though motivating comments for specific theories are not unheard of. 
However, tensors are inherently independent of coordinate systems, and any 
theory of gravity, indeed any theory of nature, must be written in tensor 
form to preserve this independence. What has this to do with the 
Equivalence Principle?  TIA, AG*

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Re: Principle of Equivalence

2020-07-04 Thread John Clark

On Fri, Jul 3, 2020 at 8:41 PM Alan Grayson  wrote:

*> Supposedly, the EP gave Einstein his key insight for GR, but his
> November 1915 doesn't reference it, not once! AG*
>

Einstein didn't need to spell it out because he found a tensor to describe
how things move through spacetime, and tensors by their very mathematical
nature are frame indifferent, if a tensor works in one reference frame it
will work in any reference frame. And in scientific papers it's not
customary to give a history of the evolution of your thought process or
anecdotes about how you happen to come up with your idea, you just state
your idea and then make suggestions about how it could be tested.

 John K Clark

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Re: Principle of Equivalence

2020-07-03 Thread Alan Grayson



On Thursday, July 2, 2020 at 2:20:50 AM UTC-6, Alan Grayson wrote:
>
>
>
> On Wednesday, July 1, 2020 at 12:18:43 AM UTC-6, Alan Grayson wrote:
>>
>> How, exactly, is the Principle of Equivalence used by Einstein to develop 
>> GR? TIA, AG
>>
>
> Is it because a description of gravity can be achieved by locally 
> substituting accelerating frames for gravity? Does it imply that paths in 
> space-time must be curved? It's not clear to me exactly how the EP is 
> applied. TIA, AG
>

Supposedly, the EP gave Einstein his key insight for GR, but his November 
1915 doesn't reference it, not once! AG

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Re: Principle of Equivalence

2020-07-02 Thread Alan Grayson



On Wednesday, July 1, 2020 at 12:18:43 AM UTC-6, Alan Grayson wrote:
>
> How, exactly, is the Principle of Equivalence used by Einstein to develop 
> GR? TIA, AG
>

Is it because a description of gravity can be achieved by locally 
substituting accelerating frames for gravity? Does it imply that paths in 
space-time must be curved? It's not clear to me exactly how the EP is 
applied. TIA, AG

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Principle of Equivalence

2020-07-01 Thread Alan Grayson

How, exactly, is the Principle of Equivalence used by Einstein to develop 
GR? TIA, AG

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Re: Questions about the Equivalence Principle (EP) and GR

2019-05-09 Thread Alan Grayson

Did Einstein "derive" the field equation using the 5 postulates of GR, or 
did he guess what they had to be based on what the postulates implied? I 
ask this because I recall reading that the field equations published in his 
1916 paper were those he had rejected around 1913. How could the final 
equations be "derived" if they were rejected earlier? The fact that he 
later adds the cosmological constant to satisfy a stable universe seems to 
suggest he was making guesses based on what he thought the postulates 
implied. AG

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Re: Questions about the Equivalence Principle (EP) and GR

2019-04-24 Thread Philip Thrift



On Wednesday, April 24, 2019 at 8:59:52 PM UTC-5, Brent wrote:
>
>
>
> On 4/24/2019 6:36 PM, agrays...@gmail.com  wrote:
>
>
>
> On Wednesday, April 24, 2019 at 6:46:49 PM UTC-6, Brent wrote: 
>>
>>
>>
>> On 4/24/2019 4:17 PM, agrays...@gmail.com wrote:
>>
>>
>>
>> On Wednesday, April 24, 2019 at 5:11:13 PM UTC-6, agrays...@gmail.com 
>> wrote: 
>>>
>>>
>>>
>>> On Wednesday, April 24, 2019 at 3:34:28 PM UTC-6, Brent wrote: 



 On 4/21/2019 7:35 PM, agrays...@gmail.com wrote:



 On Sunday, April 21, 2019 at 8:07:28 PM UTC-6, Brent wrote: 
>
>
>
> On 4/21/2019 6:31 PM, agrays...@gmail.com wrote:
>
> *Here's something odd. At 9:45 in Susskind's Lecture 2 on GR, he says 
> the metric tensor is a Kronecker delta function. But I could swear that 
> the 
> diagonal of -1,1,1,1 represents flat space in SR. AG??*
>
>
> What's odd about that??? Flat space is just special case of curved 
> space in which the curvature is zero.
>
> Brent
>

 *Sure, but he seems to be saying that the Kronecker delta is the metric 
 tensor for curved space. Isn't that how you interpret his comment?*


 No.?? After he goes thru the derivation with delta function in it, then 
 he says it's different for a curve?? space.

 Brent

>>>
>>> *I just reviewed it again. That's not my reading. In any event, it's not 
>>> clear what he means, and using Bruno's suggestion, t' --> it,?? doesn't 
>>> really help either since you end up with the Lorentz metric which is far 
>>> from Euclidean intuition for demonstrating deviations from flatness. 
>>> Further, there are transformations that keep spacetime flat with NON-zero 
>>> off diagonal elements, such as a simple rotation. AG??*
>>>
>>
>>
>> *Using the Lorentz metric, how is "flat" spacetime defined 
>> mathematically? AG *
>>
>>
>> The general definition is that the Riemann tensor is zero.?? This is 
>> independent of what coordinate system is used.?? 
>> https://en.wikipedia.org/wiki/Riemann_curvature_tensor
>>
>> If the Lorentz metric applies globally the space is flat.
>>
>> Brent
>>
>
> Are the double question marks significant in some way, or typos? AG 
>
> They are some glitch in my email program which puts in extra ??? It is 
> mysteriously inconsistent.
>
> Brent
>
>
I can't imagine interfacing with Google Groups via anything else (like any 
email system) but its own web interface.

- pt

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Re: Questions about the Equivalence Principle (EP) and GR

2019-04-24 Thread Philip Thrift



On Wednesday, April 24, 2019 at 6:17:14 PM UTC-5, agrays...@gmail.com wrote:
>
>
>
> On Wednesday, April 24, 2019 at 5:11:13 PM UTC-6, agrays...@gmail.com 
> wrote:
>>
>>
>>
>> On Wednesday, April 24, 2019 at 3:34:28 PM UTC-6, Brent wrote:
>>>
>>>
>>>
>>> On 4/21/2019 7:35 PM, agrays...@gmail.com wrote:
>>>
>>>
>>>
>>> On Sunday, April 21, 2019 at 8:07:28 PM UTC-6, Brent wrote: 



 On 4/21/2019 6:31 PM, agrays...@gmail.com wrote:

 *Here's something odd. At 9:45 in Susskind's Lecture 2 on GR, he says 
 the metric tensor is a Kronecker delta function. But I could swear that 
 the 
 diagonal of -1,1,1,1 represents flat space in SR. AG??*


 What's odd about that??? Flat space is just special case of curved 
 space in which the curvature is zero.

 Brent

>>>
>>> *Sure, but he seems to be saying that the Kronecker delta is the metric 
>>> tensor for curved space. Isn't that how you interpret his comment?*
>>>
>>>
>>> No.?? After he goes thru the derivation with delta function in it, then 
>>> he says it's different for a curve?? space.
>>>
>>> Brent
>>>
>>
>> *I just reviewed it again. That's not my reading. In any event, it's not 
>> clear what he means, and using Bruno's suggestion, t' --> it,  doesn't 
>> really help either since you end up with the Lorentz metric which is far 
>> from Euclidean intuition for demonstrating deviations from flatness. 
>> Further, there are transformations that keep spacetime flat with NON-zero 
>> off diagonal elements, such as a simple rotation. AG *
>>
>
> *Using the Lorentz metric, how is "flat" spacetime defined mathematically? 
> AG *
>



See https://en.wikipedia.org/wiki/Metric_tensor#Examples

Euclidean metric vs.
Lorentzian metrics  "In flat Minkowski space 
 ..."

- pt

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Re: Questions about the Equivalence Principle (EP) and GR

2019-04-24 Thread 'Brent Meeker' via Everything List




On 4/24/2019 6:36 PM, agrayson2...@gmail.com wrote:



On Wednesday, April 24, 2019 at 6:46:49 PM UTC-6, Brent wrote:



On 4/24/2019 4:17 PM, agrays...@gmail.com  wrote:



On Wednesday, April 24, 2019 at 5:11:13 PM UTC-6,
agrays...@gmail.com wrote:



On Wednesday, April 24, 2019 at 3:34:28 PM UTC-6, Brent wrote:



On 4/21/2019 7:35 PM, agrays...@gmail.com wrote:



On Sunday, April 21, 2019 at 8:07:28 PM UTC-6, Brent wrote:



On 4/21/2019 6:31 PM, agrays...@gmail.com wrote:

*Here's something odd. At 9:45 in Susskind's
Lecture 2 on GR, he says the metric tensor is a
Kronecker delta function. But I could swear that
the diagonal of -1,1,1,1 represents flat space in
SR. AG??*


What's odd about that??? Flat space is just special
case of curved space in which the curvature is zero.

Brent


*Sure, but he seems to be saying that the Kronecker
delta is the metric tensor for curved space. Isn't that
how you interpret his comment?*


No.?? After he goes thru the derivation with delta
function in it, then he says it's different for a curve??
space.

Brent


*I just reviewed it again. That's not my reading. In any
event, it's not clear what he means, and using Bruno's
suggestion, t' --> it,?? doesn't really help either since you
end up with the Lorentz metric which is far from Euclidean
intuition for demonstrating deviations from flatness.
Further, there are transformations that keep spacetime flat
with NON-zero off diagonal elements, such as a simple
rotation. AG??*


*Using the Lorentz metric, how is "flat" spacetime defined
mathematically? AG
*



The general definition is that the Riemann tensor is zero.?? This
is independent of what coordinate system is used.??
https://en.wikipedia.org/wiki/Riemann_curvature_tensor


If the Lorentz metric applies globally the space is flat.

Brent


Are the double question marks significant in some way, or typos? AG

They are some glitch in my email program which puts in extra ??? It is 
mysteriously inconsistent.


Brent

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Re: Questions about the Equivalence Principle (EP) and GR



On Wednesday, April 24, 2019 at 6:46:49 PM UTC-6, Brent wrote:
>
>
>
> On 4/24/2019 4:17 PM, agrays...@gmail.com  wrote:
>
>
>
> On Wednesday, April 24, 2019 at 5:11:13 PM UTC-6, agrays...@gmail.com 
> wrote: 
>>
>>
>>
>> On Wednesday, April 24, 2019 at 3:34:28 PM UTC-6, Brent wrote: 
>>>
>>>
>>>
>>> On 4/21/2019 7:35 PM, agrays...@gmail.com wrote:
>>>
>>>
>>>
>>> On Sunday, April 21, 2019 at 8:07:28 PM UTC-6, Brent wrote: 



 On 4/21/2019 6:31 PM, agrays...@gmail.com wrote:

 *Here's something odd. At 9:45 in Susskind's Lecture 2 on GR, he says 
 the metric tensor is a Kronecker delta function. But I could swear that 
 the 
 diagonal of -1,1,1,1 represents flat space in SR. AG??*


 What's odd about that??? Flat space is just special case of curved 
 space in which the curvature is zero.

 Brent

>>>
>>> *Sure, but he seems to be saying that the Kronecker delta is the metric 
>>> tensor for curved space. Isn't that how you interpret his comment?*
>>>
>>>
>>> No.?? After he goes thru the derivation with delta function in it, then 
>>> he says it's different for a curve?? space.
>>>
>>> Brent
>>>
>>
>> *I just reviewed it again. That's not my reading. In any event, it's not 
>> clear what he means, and using Bruno's suggestion, t' --> it,?? doesn't 
>> really help either since you end up with the Lorentz metric which is far 
>> from Euclidean intuition for demonstrating deviations from flatness. 
>> Further, there are transformations that keep spacetime flat with NON-zero 
>> off diagonal elements, such as a simple rotation. AG??*
>>
>
>
> *Using the Lorentz metric, how is "flat" spacetime defined mathematically? 
> AG *
>
>
> The general definition is that the Riemann tensor is zero.?? This is 
> independent of what coordinate system is used.?? 
> https://en.wikipedia.org/wiki/Riemann_curvature_tensor
>
> If the Lorentz metric applies globally the space is flat.
>
> Brent
>

Are the double question marks significant in some way, or typos? AG 

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Re: Questions about the Equivalence Principle (EP) and GR

2019-04-24 Thread 'Brent Meeker' via Everything List




On 4/24/2019 4:17 PM, agrayson2...@gmail.com wrote:



On Wednesday, April 24, 2019 at 5:11:13 PM UTC-6, agrays...@gmail.com 
wrote:




On Wednesday, April 24, 2019 at 3:34:28 PM UTC-6, Brent wrote:



On 4/21/2019 7:35 PM, agrays...@gmail.com wrote:



On Sunday, April 21, 2019 at 8:07:28 PM UTC-6, Brent wrote:



On 4/21/2019 6:31 PM, agrays...@gmail.com wrote:

*Here's something odd. At 9:45 in Susskind's Lecture 2
on GR, he says the metric tensor is a Kronecker delta
function. But I could swear that the diagonal of
-1,1,1,1 represents flat space in SR. AG??*


What's odd about that??? Flat space is just special case
of curved space in which the curvature is zero.

Brent


*Sure, but he seems to be saying that the Kronecker delta is
the metric tensor for curved space. Isn't that how you
interpret his comment?*


No.?? After he goes thru the derivation with delta function in
it, then he says it's different for a curve?? space.

Brent


*I just reviewed it again. That's not my reading. In any event,
it's not clear what he means, and using Bruno's suggestion, t' -->
it,?? doesn't really help either since you end up with the Lorentz
metric which is far from Euclidean intuition for demonstrating
deviations from flatness. Further, there are transformations that
keep spacetime flat with NON-zero off diagonal elements, such as a
simple rotation. AG *


*Using the Lorentz metric, how is "flat" spacetime defined 
mathematically? AG

*



The general definition is that the Riemann tensor is zero.?? This is 
independent of what coordinate system is used.

https://en.wikipedia.org/wiki/Riemann_curvature_tensor

If the Lorentz metric applies globally the space is flat.

Brent



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Re: Questions about the Equivalence Principle (EP) and GR



On Wednesday, April 24, 2019 at 6:04:43 PM UTC-6, Brent wrote:
>
>
>
> On 4/24/2019 4:11 PM, agrays...@gmail.com  wrote:
>
>
>
> On Wednesday, April 24, 2019 at 3:34:28 PM UTC-6, Brent wrote: 
>>
>>
>>
>> On 4/21/2019 7:35 PM, agrays...@gmail.com wrote:
>>
>>
>>
>> On Sunday, April 21, 2019 at 8:07:28 PM UTC-6, Brent wrote: 
>>>
>>>
>>>
>>> On 4/21/2019 6:31 PM, agrays...@gmail.com wrote:
>>>
>>> *Here's something odd. At 9:45 in Susskind's Lecture 2 on GR, he says 
>>> the metric tensor is a Kronecker delta function. But I could swear that the 
>>> diagonal of -1,1,1,1 represents flat space in SR. AG??*
>>>
>>>
>>> What's odd about that??? Flat space is just special case of curved space 
>>> in which the curvature is zero.
>>>
>>> Brent
>>>
>>
>> *Sure, but he seems to be saying that the Kronecker delta is the metric 
>> tensor for curved space. Isn't that how you interpret his comment?*
>>
>>
>> No.?? After he goes thru the derivation with delta function in it, then 
>> he says it's different for a curve?? space.
>>
>> Brent
>>
>
> *I just reviewed it again. That's not my reading. In any event, it's not 
> clear what he means, and using Bruno's suggestion, t' --> it,?? doesn't 
> really help either since you end up with the Lorentz metric which is far 
> from Euclidean intuition for demonstrating deviations from flatness. *
>
>
> It was NOT demonstrating deviation from flatness.??
>

*I know. He just offered a final comment that deviations from flatness 
corresponds to non-zero off diagonal elements, so it got me wondering how 
flatness is mathematically defined for a Lorentz metric. I agree I should 
focus on the reference I posted. AG*
 

> I don't know what the guy was intending to demonstrate but he started with 
> assuming flatness, got a metric, and then remarked that it's different for 
> curve space.?? So what's your problem??? Read
>
> arXiv:1608.05752v1 [physics.hist-ph] 19 Aug 2016
>
> and stop fussing about some video.
>
> Brent
>
> *Further, there are transformations that keep spacetime flat with NON-zero 
> off diagonal elements, such as a simple rotation. AG??*
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>
>

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Re: Questions about the Equivalence Principle (EP) and GR

2019-04-24 Thread 'Brent Meeker' via Everything List




On 4/24/2019 4:11 PM, agrayson2...@gmail.com wrote:



On Wednesday, April 24, 2019 at 3:34:28 PM UTC-6, Brent wrote:



On 4/21/2019 7:35 PM, agrays...@gmail.com  wrote:



On Sunday, April 21, 2019 at 8:07:28 PM UTC-6, Brent wrote:



On 4/21/2019 6:31 PM, agrays...@gmail.com wrote:

*Here's something odd. At 9:45 in Susskind's Lecture 2 on
GR, he says the metric tensor is a Kronecker delta function.
But I could swear that the diagonal of -1,1,1,1 represents
flat space in SR. AG??*


What's odd about that??? Flat space is just special case of
curved space in which the curvature is zero.

Brent


*Sure, but he seems to be saying that the Kronecker delta is the
metric tensor for curved space. Isn't that how you interpret his
comment?*


No.?? After he goes thru the derivation with delta function in it,
then he says it's different for a curve?? space.

Brent


*I just reviewed it again. That's not my reading. In any event, it's 
not clear what he means, and using Bruno's suggestion, t' --> it,?? 
doesn't really help either since you end up with the Lorentz metric 
which is far from Euclidean intuition for demonstrating deviations 
from flatness. *


It was NOT demonstrating deviation from flatness.?? I don't know what the 
guy was intending to demonstrate but he started with assuming flatness, 
got a metric, and then remarked that it's different for curve space.?? So 
what's your problem??? Read


arXiv:1608.05752v1 [physics.hist-ph] 19 Aug 2016

and stop fussing about some video.

Brent
*Further, there are transformations that keep spacetime flat with 
NON-zero off diagonal elements, such as a simple rotation. AG *

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Re: Questions about the Equivalence Principle (EP) and GR



On Wednesday, April 24, 2019 at 5:11:13 PM UTC-6, agrays...@gmail.com wrote:
>
>
>
> On Wednesday, April 24, 2019 at 3:34:28 PM UTC-6, Brent wrote:
>>
>>
>>
>> On 4/21/2019 7:35 PM, agrays...@gmail.com wrote:
>>
>>
>>
>> On Sunday, April 21, 2019 at 8:07:28 PM UTC-6, Brent wrote: 
>>>
>>>
>>>
>>> On 4/21/2019 6:31 PM, agrays...@gmail.com wrote:
>>>
>>> *Here's something odd. At 9:45 in Susskind's Lecture 2 on GR, he says 
>>> the metric tensor is a Kronecker delta function. But I could swear that the 
>>> diagonal of -1,1,1,1 represents flat space in SR. AG??*
>>>
>>>
>>> What's odd about that??? Flat space is just special case of curved space 
>>> in which the curvature is zero.
>>>
>>> Brent
>>>
>>
>> *Sure, but he seems to be saying that the Kronecker delta is the metric 
>> tensor for curved space. Isn't that how you interpret his comment?*
>>
>>
>> No.?? After he goes thru the derivation with delta function in it, then 
>> he says it's different for a curve?? space.
>>
>> Brent
>>
>
> *I just reviewed it again. That's not my reading. In any event, it's not 
> clear what he means, and using Bruno's suggestion, t' --> it,  doesn't 
> really help either since you end up with the Lorentz metric which is far 
> from Euclidean intuition for demonstrating deviations from flatness. 
> Further, there are transformations that keep spacetime flat with NON-zero 
> off diagonal elements, such as a simple rotation. AG *
>

*Using the Lorentz metric, how is "flat" spacetime defined mathematically? 
AG *

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Re: Questions about the Equivalence Principle (EP) and GR



On Wednesday, April 24, 2019 at 3:34:28 PM UTC-6, Brent wrote:
>
>
>
> On 4/21/2019 7:35 PM, agrays...@gmail.com  wrote:
>
>
>
> On Sunday, April 21, 2019 at 8:07:28 PM UTC-6, Brent wrote: 
>>
>>
>>
>> On 4/21/2019 6:31 PM, agrays...@gmail.com wrote:
>>
>> *Here's something odd. At 9:45 in Susskind's Lecture 2 on GR, he says the 
>> metric tensor is a Kronecker delta function. But I could swear that the 
>> diagonal of -1,1,1,1 represents flat space in SR. AG??*
>>
>>
>> What's odd about that??? Flat space is just special case of curved space 
>> in which the curvature is zero.
>>
>> Brent
>>
>
> *Sure, but he seems to be saying that the Kronecker delta is the metric 
> tensor for curved space. Isn't that how you interpret his comment?*
>
>
> No.?? After he goes thru the derivation with delta function in it, then he 
> says it's different for a curve?? space.
>
> Brent
>

*I just reviewed it again. That's not my reading. In any event, it's not 
clear what he means, and using Bruno's suggestion, t' --> it,  doesn't 
really help either since you end up with the Lorentz metric which is far 
from Euclidean intuition for demonstrating deviations from flatness. 
Further, there are transformations that keep spacetime flat with NON-zero 
off diagonal elements, such as a simple rotation. AG *

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Re: Questions about the Equivalence Principle (EP) and GR

2019-04-24 Thread 'Brent Meeker' via Everything List




On 4/21/2019 7:35 PM, agrayson2...@gmail.com wrote:



On Sunday, April 21, 2019 at 8:07:28 PM UTC-6, Brent wrote:



On 4/21/2019 6:31 PM, agrays...@gmail.com  wrote:

*Here's something odd. At 9:45 in Susskind's Lecture 2 on GR, he
says the metric tensor is a Kronecker delta function. But I could
swear that the diagonal of -1,1,1,1 represents flat space in SR. AG *


What's odd about that??? Flat space is just special case of curved
space in which the curvature is zero.

Brent


*Sure, but he seems to be saying that the Kronecker delta is the 
metric tensor for curved space. Isn't that how you interpret his comment?*


No.?? After he goes thru the derivation with delta function in it, then 
he says it's different for a curve?? space.


Brent

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Re: Questions about the Equivalence Principle (EP) and GR



On Wednesday, April 24, 2019 at 11:29:36 AM UTC-6, agrays...@gmail.com 
wrote:
>
>
>
> On Wednesday, April 24, 2019 at 11:06:10 AM UTC-6, Bruno Marchal wrote:
>>
>>
>> On 23 Apr 2019, at 13:39, agrays...@gmail.com wrote:
>>
>>
>>
>> On Tuesday, April 23, 2019 at 4:00:26 AM UTC-6, Bruno Marchal wrote:
>>>
>>>
>>> On 20 Apr 2019, at 23:14, agrays...@gmail.com wrote:
>>>
>>>
>>>
>>> On Friday, April 19, 2019 at 2:53:00 AM UTC-6, Bruno Marchal wrote:


 On 19 Apr 2019, at 04:08, agrays...@gmail.com wrote:



 On Thursday, April 18, 2019 at 6:53:33 PM UTC-6, Brent wrote:
>
> Sorry, I don't remember what, if anything, I intended to text.
>
> I'm not expert on how Einstein arrived at his famous field equations.  
> I know that he insisted on them being tensor equations so that they would 
> have the same form in all coordinate systems.  That may sound like a 
> mathematical technicality, but it is really to ensure that the things in 
> the equation, the tensors, could have a physical interpretation.  He also 
> limited himself to second order differentials, probably as a matter of 
> simplicity.  And he excluded torsion, but I don't know why.  And of 
> course 
> he knew it had to reproduce Newtonian gravity in the weak/slow limit.
>
> Brent
>

 Here's a link which might help;

  https://arxiv.org/pdf/1608.05752.pdf



 Yes. That is helpful.

 The following (long!) video can also help (well, it did help me)

 https://www.youtube.com/watch?v=foRPKAKZWx8


 Bruno

>>>
>>> *I've been viewing this video. I don't see how he established that the 
>>> metric tensor is a correction for curved spacetime. AG *
>>>
>>>
>>> ds^2 = dx^2 + dy^2 is Pythagorus theorem, in the plane. The “g_mu,nu” 
>>> are the coefficients needed to ensure un non-planner (curved) metric, and 
>>> they can be use to define the curvature.
>>>
>>> Bruno 
>>>
>>
>> *Thanks for your time, but I don't think you have a clue what the issues 
>> are here. And, as a alleged expert in logic, it puts your other claims in 
>> jeopardy. Firstly, in the video you offered, the presenter has a Kronecker 
>> delta as the leading multiplicative factor in his definition of the Metric 
>> Tensor, which implies all off diagonal terms are zero. And even if that 
>> term were omitted, your reference to Pythagorus leaves much to be desired. 
>> In SR we're dealing with a 4 dim space with the Lorentz metric, not a 
>> Euclidean space where the Pythagorean theorem applies. How does a diagonal 
>> signature of -1,1,1,1 imply flat space? Why would non-zero off diagonal 
>> elements have anything to do with a departure from flat space under 
>> Lorentz's metric? AG *
>>
>>
>>
>> Oops sorry. Since long I do relativity only in its euclidian form, 
>> through the transformation t' := it. (I being the square root of -1). This 
>> makes Minkowski euclidean again. I should have mentioned this.
>>
>> Bruno
>>
>
>  
> *How does it make Minkowski euclidean if you're not dealing with 
> spacetime. Euclidean and departures from flat require real coordinates. AG*
>

*Using transformation t' --> it  yields a pseudo-Euclidean or 
pseudo-Minkowski space, and can't be used to explain the off-diagonal 
elements of the metric tensor as indicative of lack of Euclidean flatness. 
AG*

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Re: Questions about the Equivalence Principle (EP) and GR