Re: Equivalence Principle and Einstein Field Equations

[agrayson2000]

On Tuesday, December 19, 2017 at 3:32:22 AM UTC, Brent wrote:
>
>
>
> On 12/18/2017 6:36 PM, agrays...@gmail.com  wrote:
>
>
>
> On Monday, December 18, 2017 at 8:48:08 PM UTC, Brent wrote: 
>>
>>
>>
>> On 12/18/2017 12:19 AM, agrays...@gmail.com wrote:
>>
>>
>>
>> On Sunday, December 17, 2017 at 10:39:18 PM UTC, agrays...@gmail.com 
>> wrote: 
>>>
>>>
>>>
>>> On Sunday, December 17, 2017 at 12:21:27 AM UTC, Brent wrote: 



 On 12/16/2017 2:59 PM, agrays...@gmail.com wrote:

 There's a problem applying SR in this situation because neither the 
 ground or orbiting clock is an inertial frame.AG


 An orbiting clock is in an inertial frame.  An inertial frame is just 
 one in which no forces are acting (and gravity is not a force) so that it 
 moves with constant momentum along a geodesic.  Although it's convenient 
 for engineering calculations, from a fundamental veiwpoint there is no 
 separate special relativity and general relativity and no separate clock 
 corrections.  General is just special relativity in curved spacetime.  So 
 clocks measure the 4-space interval along their path - whether that path 
 is 
 geodesic (i.e. inertial) or accelerated.

>>>
>>> *Interesting way to look at it. So free falling in a gravity field is an 
>>> extension of SR. But the thing I find puzzling is that in GR the curvature 
>>> of space-time is caused by the presence of mass, yet I can draw the path of 
>>> an accelerated body as necessarily a curve in a space-time diagram. I am 
>>> having trouble resolving these different sources of curvature. AG*
>>>
>>
>> *Einstein must have figured that since gravity produces an acceleration 
>> field, and accelerating test particles move along curved paths in 
>> space-time, he could replace acceleration by inertial paths in a space-time 
>> curved by the presence of mass-energy. But now, when comparing test 
>> particles moving along different paths in space-time, he couldn't use the 
>> Lorentz transformation because the relative velocities of the frames are 
>> not necessarily constant. So how did he propose to find the correct 
>> transformation equations, and what are they? And what were the laws of 
>> physics, in this case gravity, that had to be invariant? AG*
>>
>>
>> What's invariant is the measure along a path in spacetime - it's what an 
>> ideal clock measures.  The relation between the measure along two different 
>> paths obviously depends on the lumpiness of the spacetime through which 
>> they travel.  It's as if I headed north thru the Sierras while you sailed 
>> up the coast.  There's no simple relation between our path lengths even if 
>> we travel between the same two points.  
>>
>
> *So what's invariant along along two paths with the same endpoints? *
>
>
> It's not about two paths.  The length of each path as measured using 
> Einstein's  theory of the metric (i.e. as warped by mass-energy) is an 
> invariant.  Just as the distance your car's odometer would measure driving 
> from NY to LA, it's some number and it depends on (a) the path you took and 
> (b) the topography along that path.  The interesting point is that two such 
> paths between a pair of events are different durations as measured by 
> clocks carried along the trips.  That's contrary to Newton, for whom time 
> was an invariant.
>
> *Not clear from what you write. But whatever it is, why is that deemed to 
> be invariant? *
>
>
> Because it doesn't depend on what reference system you use in spacetime.  
> It's measuring a distance which is a real thing, not something 
> relative/subjective.
>
> *Shouldn't it be the laws of physics, in this case gravity, and hence the 
> field equations? AG *
>
>
> It's the basis for them.  They can be written in terms of an extremal 
> principle for the invariant path lengths.
>



*Is this the method Einstein used to derive the field equations? This is 
one of my key interests in this subject; to understand the method he used 
to derive the field equations. If so, why is invariant path lengths such a 
crucial condition? I agree that physics seeks invariants, but why this 
particular one? AG* 

The Lorentz transformation is just the simple limiting case of flat, smooth 
> spacetime.  It's useful because in a sufficiently small local region 
> spacetime is going to be flat and smooth.
>
> Brent
>
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Re: Equivalence Principle and Einstein Field Equations

[agrayson2000]

On Tuesday, December 19, 2017 at 3:34:41 AM UTC, Brent wrote:
>
>
>
> On 12/18/2017 6:54 PM, agrays...@gmail.com  wrote:
>
>
>
> On Tuesday, December 19, 2017 at 2:36:32 AM UTC, agrays...@gmail.com 
> wrote: 
>>
>>
>>
>> On Monday, December 18, 2017 at 8:48:08 PM UTC, Brent wrote: 
>>>
>>>
>>>
>>> On 12/18/2017 12:19 AM, agrays...@gmail.com wrote:
>>>
>>>
>>>
>>> On Sunday, December 17, 2017 at 10:39:18 PM UTC, agrays...@gmail.com 
>>> wrote: 



 On Sunday, December 17, 2017 at 12:21:27 AM UTC, Brent wrote: 
>
>
>
> On 12/16/2017 2:59 PM, agrays...@gmail.com wrote:
>
> There's a problem applying SR in this situation because neither the 
> ground or orbiting clock is an inertial frame.AG
>
>
> An orbiting clock is in an inertial frame.  An inertial frame is just 
> one in which no forces are acting (and gravity is not a force) so that it 
> moves with constant momentum along a geodesic.  Although it's convenient 
> for engineering calculations, from a fundamental veiwpoint there is no 
> separate special relativity and general relativity and no separate clock 
> corrections.  General is just special relativity in curved spacetime.  So 
> clocks measure the 4-space interval along their path - whether that path 
> is 
> geodesic (i.e. inertial) or accelerated.
>

 *Interesting way to look at it. So free falling in a gravity field is 
 an extension of SR. But the thing I find puzzling is that in GR the 
 curvature of space-time is caused by the presence of mass, yet I can draw 
 the path of an accelerated body as necessarily a curve in a space-time 
 diagram. I am having trouble resolving these different sources of 
 curvature. AG*

>>>
>>> *Einstein must have figured that since gravity produces an acceleration 
>>> field, and accelerating test particles move along curved paths in 
>>> space-time, he could replace acceleration by inertial paths in a space-time 
>>> curved by the presence of mass-energy. But now, when comparing test 
>>> particles moving along different paths in space-time, he couldn't use the 
>>> Lorentz transformation because the relative velocities of the frames are 
>>> not necessarily constant. So how did he propose to find the correct 
>>> transformation equations, and what are they? And what were the laws of 
>>> physics, in this case gravity, that had to be invariant? AG*
>>>
>>>
>>> What's invariant is the measure along a path in spacetime - it's what an 
>>> ideal clock measures.  The relation between the measure along two different 
>>> paths obviously depends on the lumpiness of the spacetime through which 
>>> they travel.  It's as if I headed north thru the Sierras while you sailed 
>>> up the coast.  There's no simple relation between our path lengths even if 
>>> we travel between the same two points.  
>>>
>>
>> *So what's invariant along along two paths with the same endpoints? Not 
>> clear from what you write. But whatever it is, why is that deemed to be 
>> invariant? Shouldn't it be the laws of physics, in this case gravity, and 
>> hence the field equations? AG *
>>
>
> *I think you mean the dS^2 value is invariant along two paths with the 
> same endpoints, but not the path length of the spatial coordinates. 
> Correct? *
>
>
> Right.
>
> *But why is this particular invariant so important, and perhaps used as a 
> guide to Einstein? AG*
>
>
> Invariants are always the important things in physics because they are 
> what we can have intersubjective agreement on.
>
> Brent
>

*IIUC, the field equations are covariant, which means coordinate system 
independent. Isn't Newton's Law of Gravitation also coordinate independent? 
That is, if we use Newton to calculate the planetary orbits, won't we get 
the same results in different coordinate systems? ... Is there a 
distinction in GR between frame independence and coordinate independence? 
AG*

>
>
>> The Lorentz transformation is just the simple limiting case of flat, 
>>> smooth spacetime.  It's useful because in a sufficiently small local region 
>>> spacetime is going to be flat and smooth.
>>>
>>> Brent
>>>
>> -- 
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abc conjecture

[Brent Meeker]

http://www.math.columbia.edu/~woit/wordpress/?p=5104

How much more acute this problem will become when AI reaches human and 
super-human levels.


Brent

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Re: Equivalence Principle and Einstein Field Equations

[Brent Meeker]

On 12/18/2017 6:54 PM, agrayson2...@gmail.com wrote:



On Tuesday, December 19, 2017 at 2:36:32 AM UTC, agrays...@gmail.com 
wrote:




On Monday, December 18, 2017 at 8:48:08 PM UTC, Brent wrote:



On 12/18/2017 12:19 AM, agrays...@gmail.com wrote:



On Sunday, December 17, 2017 at 10:39:18 PM UTC,
agrays...@gmail.com wrote:



On Sunday, December 17, 2017 at 12:21:27 AM UTC, Brent
wrote:



On 12/16/2017 2:59 PM, agrays...@gmail.com wrote:

There's a problem applying SR in this situation
because neither the ground or orbiting clock is an
inertial frame.AG


An orbiting clock is in an inertial frame. An
inertial frame is just one in which no forces are
acting (and gravity is not a force) so that it moves
with constant momentum along a geodesic.  Although
it's convenient for engineering calculations, from a
fundamental veiwpoint there is no separate special
relativity and general relativity and no separate
clock corrections.  General is just special
relativity in curved spacetime.  So clocks measure
the 4-space interval along their path - whether that
path is geodesic (i.e. inertial) or accelerated.


*Interesting way to look at it. So free falling in a
gravity field is an extension of SR. But the thing I find
puzzling is that in GR the curvature of space-time is
caused by the presence of mass, yet I can draw the path
of an accelerated body as _necessarily_ a curve in a
space-time diagram. I am having trouble resolving these
different sources of curvature. AG*


*Einstein must have figured that since gravity produces an
acceleration field, and accelerating test particles move
along curved paths in space-time, he could replace
acceleration by inertial paths in a space-time curved by the
presence of mass-energy. But now, when comparing test
particles moving along different paths in space-time, he
couldn't use the Lorentz transformation because the relative
velocities of the frames are not necessarily constant. So how
did he propose to find the correct transformation equations,
and what are they? And what were the laws of physics, in this
case gravity, that had to be invariant? AG*


What's invariant is the measure along a path in spacetime -
it's what an ideal clock measures.  The relation between the
measure along two different paths obviously depends on the
lumpiness of the spacetime through which they travel.  It's as
if I headed north thru the Sierras while you sailed up the
coast.  There's no simple relation between our path lengths
even if we travel between the same two points.


*So what's invariant along along two paths with the same
endpoints? Not clear from what you write. But whatever it is, why
is that deemed to be invariant? Shouldn't it be the laws of
physics, in this case gravity, and hence the field equations? AG *


*I think you mean the dS^2 value is invariant along two paths with the 
same endpoints, but not the path length of the spatial coordinates. 
Correct? *


Right.*

*
*But why is this particular invariant so important, and perhaps used 
as a guide to Einstein? AG*


Invariants are always the important things in physics because they are 
what we can have intersubjective agreement on.


Brent



The Lorentz transformation is just the simple limiting case of
flat, smooth spacetime.  It's useful because in a sufficiently
small local region spacetime is going to be flat and smooth.

Brent

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Re: Equivalence Principle and Einstein Field Equations

[Brent Meeker]

On 12/18/2017 6:36 PM, agrayson2...@gmail.com wrote:



On Monday, December 18, 2017 at 8:48:08 PM UTC, Brent wrote:



On 12/18/2017 12:19 AM, agrays...@gmail.com  wrote:



On Sunday, December 17, 2017 at 10:39:18 PM UTC,
agrays...@gmail.com wrote:



On Sunday, December 17, 2017 at 12:21:27 AM UTC, Brent wrote:



On 12/16/2017 2:59 PM, agrays...@gmail.com wrote:

There's a problem applying SR in this situation because
neither the ground or orbiting clock is an inertial frame.AG


An orbiting clock is in an inertial frame.  An inertial
frame is just one in which no forces are acting (and
gravity is not a force) so that it moves with constant
momentum along a geodesic.  Although it's convenient for
engineering calculations, from a fundamental veiwpoint
there is no separate special relativity and general
relativity and no separate clock corrections.  General is
just special relativity in curved spacetime.  So clocks
measure the 4-space interval along their path - whether
that path is geodesic (i.e. inertial) or accelerated.


*Interesting way to look at it. So free falling in a gravity
field is an extension of SR. But the thing I find puzzling is
that in GR the curvature of space-time is caused by the
presence of mass, yet I can draw the path of an accelerated
body as _necessarily_ a curve in a space-time diagram. I am
having trouble resolving these different sources of
curvature. AG*


*Einstein must have figured that since gravity produces an
acceleration field, and accelerating test particles move along
curved paths in space-time, he could replace acceleration by
inertial paths in a space-time curved by the presence of
mass-energy. But now, when comparing test particles moving along
different paths in space-time, he couldn't use the Lorentz
transformation because the relative velocities of the frames are
not necessarily constant. So how did he propose to find the
correct transformation equations, and what are they? And what
were the laws of physics, in this case gravity, that had to be
invariant? AG*


What's invariant is the measure along a path in spacetime - it's
what an ideal clock measures.  The relation between the measure
along two different paths obviously depends on the lumpiness of
the spacetime through which they travel.  It's as if I headed
north thru the Sierras while you sailed up the coast.  There's no
simple relation between our path lengths even if we travel between
the same two points.


*So what's invariant along along two paths with the same endpoints? *


It's not about two paths.  The length of each path as measured using 
Einstein's  theory of the metric (i.e. as warped by mass-energy) is an 
invariant.  Just as the distance your car's odometer would measure 
driving from NY to LA, it's some number and it depends on (a) the path 
you took and (b) the topography along that path.  The interesting point 
is that two such paths between a pair of events are different durations 
as measured by clocks carried along the trips.  That's contrary to 
Newton, for whom time was an invariant.


*Not clear from what you write. But whatever it is, why is that deemed 
to be invariant? *


Because it doesn't depend on what reference system you use in 
spacetime.  It's measuring a distance which is a real thing, not 
something relative/subjective.


*Shouldn't it be the laws of physics, in this case gravity, and hence 
the field equations? AG *


It's the basis for them.  They can be written in terms of an extremal 
principle for the invariant path lengths.


Brent


The Lorentz transformation is just the simple limiting case of
flat, smooth spacetime.  It's useful because in a sufficiently
small local region spacetime is going to be flat and smooth.

Brent

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Re: Equivalence Principle and Einstein Field Equations

[agrayson2000]

On Tuesday, December 19, 2017 at 2:36:32 AM UTC, agrays...@gmail.com wrote:
>
>
>
> On Monday, December 18, 2017 at 8:48:08 PM UTC, Brent wrote:
>>
>>
>>
>> On 12/18/2017 12:19 AM, agrays...@gmail.com wrote:
>>
>>
>>
>> On Sunday, December 17, 2017 at 10:39:18 PM UTC, agrays...@gmail.com 
>> wrote: 
>>>
>>>
>>>
>>> On Sunday, December 17, 2017 at 12:21:27 AM UTC, Brent wrote: 



 On 12/16/2017 2:59 PM, agrays...@gmail.com wrote:

 There's a problem applying SR in this situation because neither the 
 ground or orbiting clock is an inertial frame.AG


 An orbiting clock is in an inertial frame.  An inertial frame is just 
 one in which no forces are acting (and gravity is not a force) so that it 
 moves with constant momentum along a geodesic.  Although it's convenient 
 for engineering calculations, from a fundamental veiwpoint there is no 
 separate special relativity and general relativity and no separate clock 
 corrections.  General is just special relativity in curved spacetime.  So 
 clocks measure the 4-space interval along their path - whether that path 
 is 
 geodesic (i.e. inertial) or accelerated.

>>>
>>> *Interesting way to look at it. So free falling in a gravity field is an 
>>> extension of SR. But the thing I find puzzling is that in GR the curvature 
>>> of space-time is caused by the presence of mass, yet I can draw the path of 
>>> an accelerated body as necessarily a curve in a space-time diagram. I am 
>>> having trouble resolving these different sources of curvature. AG*
>>>
>>
>> *Einstein must have figured that since gravity produces an acceleration 
>> field, and accelerating test particles move along curved paths in 
>> space-time, he could replace acceleration by inertial paths in a space-time 
>> curved by the presence of mass-energy. But now, when comparing test 
>> particles moving along different paths in space-time, he couldn't use the 
>> Lorentz transformation because the relative velocities of the frames are 
>> not necessarily constant. So how did he propose to find the correct 
>> transformation equations, and what are they? And what were the laws of 
>> physics, in this case gravity, that had to be invariant? AG*
>>
>>
>> What's invariant is the measure along a path in spacetime - it's what an 
>> ideal clock measures.  The relation between the measure along two different 
>> paths obviously depends on the lumpiness of the spacetime through which 
>> they travel.  It's as if I headed north thru the Sierras while you sailed 
>> up the coast.  There's no simple relation between our path lengths even if 
>> we travel between the same two points.  
>>
>
> *So what's invariant along along two paths with the same endpoints? Not 
> clear from what you write. But whatever it is, why is that deemed to be 
> invariant? Shouldn't it be the laws of physics, in this case gravity, and 
> hence the field equations? AG *
>

*I think you mean the dS^2 value is invariant along two paths with the same 
endpoints, but not the path length of the spatial coordinates. Correct? But 
why is this particular invariant so important, and perhaps used as a guide 
to Einstein? AG*

>
> The Lorentz transformation is just the simple limiting case of flat, 
>> smooth spacetime.  It's useful because in a sufficiently small local region 
>> spacetime is going to be flat and smooth.
>>
>> Brent
>>
>

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Re: Equivalence Principle and Einstein Field Equations

[agrayson2000]

On Monday, December 18, 2017 at 8:48:08 PM UTC, Brent wrote:
>
>
>
> On 12/18/2017 12:19 AM, agrays...@gmail.com  wrote:
>
>
>
> On Sunday, December 17, 2017 at 10:39:18 PM UTC, agrays...@gmail.com 
> wrote: 
>>
>>
>>
>> On Sunday, December 17, 2017 at 12:21:27 AM UTC, Brent wrote: 
>>>
>>>
>>>
>>> On 12/16/2017 2:59 PM, agrays...@gmail.com wrote:
>>>
>>> There's a problem applying SR in this situation because neither the 
>>> ground or orbiting clock is an inertial frame.AG
>>>
>>>
>>> An orbiting clock is in an inertial frame.  An inertial frame is just 
>>> one in which no forces are acting (and gravity is not a force) so that it 
>>> moves with constant momentum along a geodesic.  Although it's convenient 
>>> for engineering calculations, from a fundamental veiwpoint there is no 
>>> separate special relativity and general relativity and no separate clock 
>>> corrections.  General is just special relativity in curved spacetime.  So 
>>> clocks measure the 4-space interval along their path - whether that path is 
>>> geodesic (i.e. inertial) or accelerated.
>>>
>>
>> *Interesting way to look at it. So free falling in a gravity field is an 
>> extension of SR. But the thing I find puzzling is that in GR the curvature 
>> of space-time is caused by the presence of mass, yet I can draw the path of 
>> an accelerated body as necessarily a curve in a space-time diagram. I am 
>> having trouble resolving these different sources of curvature. AG*
>>
>
> *Einstein must have figured that since gravity produces an acceleration 
> field, and accelerating test particles move along curved paths in 
> space-time, he could replace acceleration by inertial paths in a space-time 
> curved by the presence of mass-energy. But now, when comparing test 
> particles moving along different paths in space-time, he couldn't use the 
> Lorentz transformation because the relative velocities of the frames are 
> not necessarily constant. So how did he propose to find the correct 
> transformation equations, and what are they? And what were the laws of 
> physics, in this case gravity, that had to be invariant? AG*
>
>
> What's invariant is the measure along a path in spacetime - it's what an 
> ideal clock measures.  The relation between the measure along two different 
> paths obviously depends on the lumpiness of the spacetime through which 
> they travel.  It's as if I headed north thru the Sierras while you sailed 
> up the coast.  There's no simple relation between our path lengths even if 
> we travel between the same two points.  
>

*So what's invariant along along two paths with the same endpoints? Not 
clear from what you write. But whatever it is, why is that deemed to be 
invariant? Shouldn't it be the laws of physics, in this case gravity, and 
hence the field equations? AG *

> The Lorentz transformation is just the simple limiting case of flat, 
> smooth spacetime.  It's useful because in a sufficiently small local region 
> spacetime is going to be flat and smooth.
>
> Brent
>

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Re: Schrodinger's cat problem; proposed solution

[Russell Standish]

On Mon, Dec 18, 2017 at 05:25:12PM +0100, Bruno Marchal wrote:
> 
> 
> What is the difference you make between an instrument recording the result
> and an observer? Consciousness? But that is what "Wigner's friend" shows
> difficult to admit, and besides, I thought we all agree that it is better
> that QM is the same for conscious and non conscious beings?


For me, the most important thing is the continuous/discrete
transition. I am ambivalent on whether this requires consciousness or
not. The best examplar to think about IMHO is an analogue-digital
converter (aka A/D converter), for example the microphone input
circuit on your computer. Conceptually, this device converts an input
voltage into a distinct number (eg 0-255). However, in actual fact
what it does physically is convert a voltage into a time-varying
voltage signal, conventionally interpreted as the zeros and ones of a
number communicated serially into the computer (or alternatively, fans
the voltages out into a parallel array of volatages). That
"conventionally interpreted" is the wiggle room that smuggles
consciousness back in the picture.

Nevertheless, the most important aspect is the contrast between the
continuous and the discrete. Its the FAPP in the zeroing out of
offdiagonal terms in the einselection picture, as just another
example. We could probably make most progress on the measurement
problem by focussing on just that distinction, and ignoring any other
aspect of consciousness or observerhood, since the continuous/discrete
distinction should not be controversial to anyone, and a lot in known
mathematically about it.


-- 


Dr Russell StandishPhone 0425 253119 (mobile)
Principal, High Performance Coders
Visiting Senior Research Fellowhpco...@hpcoders.com.au
Economics, Kingston University http://www.hpcoders.com.au


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Re: Equivalence Principle and Einstein Field Equations

[Brent Meeker]

On 12/18/2017 12:19 AM, agrayson2...@gmail.com wrote:



On Sunday, December 17, 2017 at 10:39:18 PM UTC, agrays...@gmail.com 
wrote:




On Sunday, December 17, 2017 at 12:21:27 AM UTC, Brent wrote:



On 12/16/2017 2:59 PM, agrays...@gmail.com wrote:

There's a problem applying SR in this situation because
neither the ground or orbiting clock is an inertial frame.AG


An orbiting clock is in an inertial frame.  An inertial frame
is just one in which no forces are acting (and gravity is not
a force) so that it moves with constant momentum along a
geodesic.  Although it's convenient for engineering
calculations, from a fundamental veiwpoint there is no
separate special relativity and general relativity and no
separate clock corrections.  General is just special
relativity in curved spacetime.  So clocks measure the 4-space
interval along their path - whether that path is geodesic
(i.e. inertial) or accelerated.


*Interesting way to look at it. So free falling in a gravity field
is an extension of SR. But the thing I find puzzling is that in GR
the curvature of space-time is caused by the presence of mass, yet
I can draw the path of an accelerated body as _necessarily_ a
curve in a space-time diagram. I am having trouble resolving these
different sources of curvature. AG*


*Einstein must have figured that since gravity produces an 
acceleration field, and accelerating test particles move along curved 
paths in space-time, he could replace acceleration by inertial paths 
in a space-time curved by the presence of mass-energy. But now, when 
comparing test particles moving along different paths in space-time, 
he couldn't use the Lorentz transformation because the relative 
velocities of the frames are not necessarily constant. So how did he 
propose to find the correct transformation equations, and what are 
they? And what were the laws of physics, in this case gravity, that 
had to be invariant? AG*


What's invariant is the measure along a path in spacetime - it's what an 
ideal clock measures.  The relation between the measure along two 
different paths obviously depends on the lumpiness of the spacetime 
through which they travel.  It's as if I headed north thru the Sierras 
while you sailed up the coast.  There's no simple relation between our 
path lengths even if we travel between the same two points.   The 
Lorentz transformation is just the simple limiting case of flat, smooth 
spacetime.  It's useful because in a sufficiently small local region 
spacetime is going to be flat and smooth.


Brent

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Re: Equivalence Principle and Einstein Field Equations

[Brent Meeker]

On 12/17/2017 2:39 PM, agrayson2...@gmail.com wrote:



On Sunday, December 17, 2017 at 12:21:27 AM UTC, Brent wrote:



On 12/16/2017 2:59 PM, agrays...@gmail.com  wrote:

There's a problem applying SR in this situation because neither
the ground or orbiting clock is an inertial frame.AG


An orbiting clock is in an inertial frame.  An inertial frame is
just one in which no forces are acting (and gravity is not a
force) so that it moves with constant momentum along a geodesic. 
Although it's convenient for engineering calculations, from a
fundamental veiwpoint there is no separate special relativity and
general relativity and no separate clock corrections.  General
relativity is just special relativity in curved spacetime.  So
clocks measure the 4-space interval along their path - whether
that path is geodesic (i.e. inertial) or accelerated.


*Interesting way to look at it. So free falling in a gravity field is 
an extension of SR. But the thing I find puzzling is that in GR the 
curvature of space-time is caused by the presence of mass, yet I can 
draw the path of an accelerated body as _necessarily_ a curve in a 
space-time diagram. I am having trouble resolving these different 
sources of curvature. AG*


An accelerated body, i.e. one a force is acting on (a rocket, you 
standing on the ground) is following a curved path that is more curved 
than the "straightest" path.  I put "straightest" in scare quotes 
because in the curved spacetime the "straight" path is a geodesic which 
is still curved...it's just the straightest possible path in the given 
spacetime.


It is not true that "I can draw the path of an accelerated body as 
necessarily a curve in a space-time diagram".  In general, if you drew a 
straight line in some coordinate representation of a curved spacetime, 
it would correspond to an accelerated (non-geodesic) path.  Imagine 
drawing a straight line past the Earth.  It would take thrust to fly a 
rocket along that path.  Of course you could construct a coordinate 
system around the Earth such that straight lines on the diagram 
corresponded to geodesics, but it would be a very messy and distorted 
coordinate system.


Brent

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Re: Schrodinger's cat problem; proposed solution

[Bruno Marchal]

On 16 Dec 2017, at 19:00, John Clark wrote:


On Thu, Dec 14, 2017 at 9:20 PM,  wrote:

​> ​I don't see how Wigner's friend presents a problem for  
Copenhagen. According to the CI, the wf collapses when the system  
measured, which is when the box is opened. What am I missing?


​According to​ ​Copenhagen​ ​Wigner's friend​ ​opens  
the cat box and that ​​collapses​ ​the cat's wave function,  
and so Wigner's friend​ ​now knows the cat's fate, but Wigner's  
friend​ ​is also in a box and Wigner​ ​himself is outside  
that box, so until Wigner opens his friend's box his friend is in a  
"I see a dead cat" state AND a "I see a live cat state".  And of  
course you could put Wigner himself in a box with somebody outside  
it and you could keep increasing the number of nested boxes until  
the entire universe is included, and that is why the Copenhagen​ ​ 
interpretation is useless if you're ​interest is in ​dealing in  
cosmology because there is nobody outside ​to​ universe observe  
it.


 And God ​is of no help unless somebody knows who collapses God's  
wave function, ​and even then there would be another unanswered  
question too obvious to mention.


And with Digital Mechanism, even a Universe cannot help. How could  
*anything* select a computation, or a class of computations, among all  
computations?
But the first person associated to the universal numbers, involved in  
the semi-computable relations, localized themselves in the relative  
way allowed by the local self-referential correctness, apparently.


Gödel's arithmetization of metamathematics  embed the mathematicians  
in the arithmetical reality/truth/model (the structure (N, 0, +, x).


Remarkably, incompleteness justfies the equivalence, at the truth  
level, of all modes p, Bp, Bp & p, etc.	, and the fact that the  
machine cannot justify those equivalences, and that they obey quite  
different logics.


Kant can be tested, by looking for time, space and the quantum "in the  
head" of the universal machine. Apparently he is right.


Bruno







​ John K Clark​




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http://iridia.ulb.ac.be/~marchal/



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Re: Schrodinger's cat problem; proposed solution

[Bruno Marchal]

On 15 Dec 2017, at 03:47, agrayson2...@gmail.com wrote:




On Friday, December 15, 2017 at 2:27:46 AM UTC, Jason wrote:


On Thu, Dec 14, 2017 at 8:20 PM,  wrote:


On Thursday, December 14, 2017 at 2:54:01 PM UTC, Jason wrote:
The solution was proposed by Everett in 1957, collapse is a  
subjective illusion.  The dead cat and its history of decomposing  
for the previous hour does not materialize out of nothing from the  
mere act of looking at it.


No measurement is made of the cat, the Geiger counter, or the atom,  
by anyone outside the isolated system of the box, so according to  
the Copenhagen Interpretation the superposition does not collapse.  
The cat is both alive and dead. That is, until someone opens the  
door to peek inside. In that instant, the wave function collapses  
and the system randomly “decides” whether the cat is alive or dead.



If the state collapses to that of the dead cat, what happens to the  
experiences of the cat who was in the superposition of being alive  
and dead over the past hour? Do they suddenly vanish as if they  
never happened at all? Perhaps they never existed in the first  
place, as Bohr’s anti-realist approach would answer. But this leads  
to another problem: if the cat is observed to be alive, do all of  
its memories and experiences over the past hour suddenly pop into  
existence? Is the cat’s experience of 15 minutes ago ever experienced?



It is one thing to believe that microscopic particles might be in  
two different states at once, but quite another to believe the same  
for a large and complex system, such as a cat. The CI implies that a  
living, breathing cat, with a consistent history and memories of the  
previous hour, can instantly materialize from the simple act of  
observation.



Schrödinger's experiment has also been extended to highlight other  
problems. The mathematical physicist Eugene Wigner discussed a  
thought experiment known as Wigner’s friend. In it, Wigner’s friend  
is in a room that is sealed off from the rest of the world and in  
that room is a box containing Schrödinger's cat. The friend opens  
the box after an hour and notices whether or not the cat is alive.  
Sometime later, Wigner opens the door to the room to check on his  
friend. When does the wave function collapse, when the friend checks  
on the cat, or when Wigner checks on his friend? If it is when the  
friend checks on the cat, then the isolated system, unobserved by  
Wigner, has already collapsed (in contradiction to the CI). Yet, if  
it does not collapse for the friend checking on the cat, this is  
another contradiction, for he has made an observation of a system in  
a superposition. The CI seems to have difficulties handling multiple  
observers. mea



I don't see how Wigner's friend presents a problem for Copenhagen.  
According to the CI, the wf collapses when the system measured,  
which is when the box is opened. What am I missing? The issue of the  
cat's memory is a different matter, problematic IMO. AG



The problem is according to the CI, an isolated system evolves  
according to the Shrodinger equation, and therefore does not  
collapse.  But it also says observation causes collapse. So when you  
have a conscious observer who is himself part of an isolated system,  
from the point of view of another conscious observer, which rule wins?


If the system isn't isolated, it cannot be in a superposition of  
states. So including the observer as part of the system is self  
defeating if one wants to do a quantum experiment. The existence of  
an observer doesn't contradict isolation of the system if the  
observer is an instrument recording the result. AG


What is the difference you make between an instrument recording the  
result and an observer? Consciousness? But that is what "Wigner's  
friend" shows difficult to admit, and besides, I thought we all agree  
that it is better that QM is the same for conscious and non conscious  
beings?


Later you might understand that there is no "universe" at all. Only  
long histories making people relatively rare, yet with a local measure  
of one, which can stabilize the mundane type of consciousness. We need  
only to assume one universal machinery (and elementary arithmetic that  
everyone know is already such a system).


Eventually "physics" is explained by the bio-psycho-theo-logy of the  
universal machine, itself reducible in arithmetic (but not just on its  
computable part).


Bruno







Jason

If one takes the stance that the first conscious entity to  
experience the result of a measurement causes collapse, whether  
isolated or not, this still leaves the problem of large macroscopic  
systems with complex histories popping into existence through  
observation. If we replace the cat with some unconscious device,  
like a sensor that prints off a receipt with the result of whether  
or not the poison was released, then a conscious observer opening  
the box 

Re: Dreamless Sleep?

[David Nyman]

On 18 December 2017 at 07:08, Brent Meeker  wrote:

>
>
> On 12/17/2017 9:03 AM, Telmo Menezes wrote:
>
> On Fri, Dec 8, 2017 at 7:53 PM, Brent Meeker  
>  wrote:
>
> On 12/8/2017 2:24 AM, Telmo Menezes wrote:
>
> On Thu, Dec 7, 2017 at 10:47 PM, Brent Meeker  
> 
> wrote:
>
> On 12/7/2017 1:01 AM, Telmo Menezes wrote:
>
> On Wed, Dec 6, 2017 at 11:50 PM, Brent Meeker  
> 
> wrote:
>
> On 12/6/2017 1:46 AM, Bruno Marchal wrote:
>
> I suspect that this is perhaps why Brent want to refer to the
> environment
> for relating consciousness to the machine, and in Artificial
> Intelligence,
> some people defend the idea that (mundane) consciousness occur only
> when
> the
> environment contradicts a little bit the quasi automatic persistent
> inference we do all the time.
>
> That's Jeff Hawkins model of consciousness: one becomes conscious of
> something when all lower, more specialized levels of the brain have
> found
> it
> not to match their predictions.
>
> In that sort of model, how does matter "know" that it is being used to
> run a forecasting algorithm? Surely it doesn't right?
>
> ?? Why surely.  It seems you're rejecting the idea that a physical system
> can be conscious just out of prejudice.
>
> Not at all. I remain agnostic on materialism vs. idealism. Maybe I am
> even a strong agnostic: I suspect that the answer to this question
> cannot be known.
>
> Assuming materialism, consciousness must indeed be a property or
> something that emerges from the interaction of fundamental particles,
> the same way that, say, life does. Ok. All that I am saying is that
> nobody has proposed any explanation of consciousness under this
> assumption that I would call a theory. The above is not a theory, in
> the same way that the Christian God is not a theory: it proposes to
> explain a simple thing by appealing to a pre-existing more complex
> thing -- in this case claiming that the act of forecasting at a very
> high level somehow leads to consciousness, but without proposing any
> first principles. It's a magical step.
>
> What would a satisfactory (to you) first principle look like.
>
> I cannot imagine one -- and this fuels my intuition that consciousness
> is more fundamental than matter,
>
>
> It fuels my intuition that it is a "wrong question".
>
> and that emergentism is a dead-end.
> But of course, my lack of imagination is not an argument. It could be
> that I am too dumb/ignorant/crazy to come up with a good emergentist
> theory. What I can -- and do -- is listen to any idea that comes up
> and have an open mind. If you have one, I will gladly listen.
>
>
> If we
> consider the analogy of life, in the early 1900's when it was considered as
> a chemical process all that could be said about it was that it involved
> using energy to construct carbon based compounds and at a high level this
> led to reproduction and natural selection and the origin of species.  Now,
> we have greatly elaborated on the molecular chemistry and can modify and
> even created DNA and RNA molecules that realize "life".  Where did we get
> past the "magical step"?  Or are you still waiting for "the atom of life" to
> be discovered?
>
> Here there is no magical step. Life can be understood all the way down
> to basic chemistry. Ok, we don't have all the details, but we are not
> missing anything fundamental. I am not waiting for the atoms of life
> because I already know what they are. You just described them above.
> Can you do that for consciousness?
>
>
> Maybe not yet, but I can imagine what they might be: self-awareness,
> construction of narratives about one's experiences, modeling other minds,...
>

​Sometimes your responses really puzzle me Brent. What you say above almost
makes it sound as though you just don't get the distinction Telmo is
pointing to. But based on what you have said at other times I think you do
get it, but because you also know that there's really no explicating that
distinction in a purely third person way, you sometimes want to say that
that's as far as explanation can legitimately go and the rest is just woo.


>
> What makes the hard problem hard is that it relates to a qualitatively
> different phenomena than anything else that we try to understand. Life
> can be talked about purely in the third person, but consciousness is
> first person by definition.
>
>
> So we are told.  But what if someone could look at a recorded MRI of you
> brain and tell you what you were thinking?
>

​Yeah, but notice also that there's only ever one person who can attest to
the truth of that.
​

>
>
> My view is that this sort of emergentism always smuggles a subtle but
> important switcheroo at some point: moving from epistemology to
> ontology.
>
> For me, emergence is an epistemic tool. It is not possible for a human
> to understand hyper-complex systems by 

Re: Schrodinger's cat problem; proposed solution

[Lawrence Crowell]

I see the issue as similar to chaos theory or statistical mechanics. The 
superposition of states in a system shifts to entanglements with states in 
an apparatus, which evolve through many states. We can think of the 
superposition of photons passing through a double slit, where if we place 
spin states at one slit we convert that superposition into the entanglement 
with spins. If we then have a general needle state this entanglement is 
spread into more states which is associated with the einselected state of a 
classical outcome. This evolution is a sort of diffusion that because of 
its complexity is extremely difficult to track. As a result we have 
decoherent sets that are in effect coarse grained sets of states.

Even if an observer could observe all possible states of the apparatus or 
the general needle state, this leads to the difficulty that the observer 
herself is also a complex of quantum states. This means that a fine grained 
description may be simply impossible. This leads to a situation where a set 
of quantum states are encoding quantum states, which can't be completely 
described in a closed system. Measurements tend to involve a classical 
system that in some ways is an open system, not closed. There is a sort of 
Universal Turing Machine or Godel numbering involved with attempting to 
describe this in a completely axiomatic manner. 

I was going to write more on this, but I am very tied up with other work. 
This is usually a very active time of the year.

Cheers LC

On Sunday, December 17, 2017 at 11:30:10 AM UTC-6, Bruno Marchal wrote:
>
>
> On 16 Dec 2017, at 13:47, Lawrence Crowell wrote:
>
> On Friday, December 15, 2017 at 1:17:09 PM UTC-6, Bruno Marchal wrote:
>>
>>
>> On 15 Dec 2017, at 06:20, Brent Meeker wrote:
>>
>>
>>
>> On 12/14/2017 6:27 PM, Jason Resch wrote:
>>
>>
>>> *I don't see how Wigner's friend presents a problem for Copenhagen. 
>>> According to the CI, the wf collapses when the system measured, which is 
>>> when the box is opened. What am I missing? The issue of the cat's memory is 
>>> a different matter, problematic IMO. AG *
>>>  
>>>
>>
>> The problem is according to the CI, an isolated system evolves according 
>> to the Shrodinger equation, and therefore does not collapse.  But it also 
>> says observation causes collapse. 
>>
>>
>> That is not CI.  CI always supposed there is a classical realm in which 
>> measurements and observations were made by classical devices.  Wigner toyed 
>> with the idea that consciousness was required, but that was never Bohr's 
>> idea of CI.  In a sense, decoherence filled in CI by providing the 
>> mechanism of collapse.
>>
>>
>> I would say that decoherence explains the illusion of a collapse in the 
>> mind of the machine keeping a diary of the results of measurement. 
>> Decoherence is relative entanglement, and the tracing-out by the relative 
>> observers.
>>
>> The decoherence theory explains that the universe differentiation is 
>> quite speedy, and why macroscopic coherence is hard to be maintained, 
>> although possible for some material, and quantum topology promises 
>> theoretically possible "solid" qubit, etc. Like you said; it is only a 
>> matter or isolation. Now, the lack of isolation makes coherence easy lost, 
>> but that means only the quasi-irreversible lack of interference with some 
>> terms of the universal wave, not their genuine disappearance, which would 
>> contradict linearity, unitarity, well, the SWE-or DIRAC-or Feynman.
>>
>> Bruno
>>
>
> You wrote a part on this with respect to Godel's theorem a few weeks ago, 
> which I lost in the huge sea of posts on this thread. I was going to 
> respond but lost the post. 
>
> Quantum mechanics is independent of measurement. 
>
>
> OK.
>
>
>
> Quantum amplitudes evolve by unitarity or Schrodinger type of evolution 
> and this is perfectly deterministic. 
>
>
> OK.
>
>
> Once one throws a measurement or decoherence into picture things become 
> less clear. 
>
>
>
> Decoherence is only relative entanglement. It is explicitly how Everett 
> explains the "illusion of collapse" in the mind of the observer-machine. 
> Things become less clear, but only because it is psychologically hard to 
> apply QM to oneself, as it involves our counterparts.
>
>
>
>
>
>
> We might then invoke Kant's *noumena* and *phenomena* as a way of 
> thinking about this. Decoherence is just a way of looking at what happens 
> to a quantum wave that is disturbed by the environment, which can include a 
> laboratory measurement. 
>
>
> Even Bohr admitted, in his reply to EPR, that such a disturbance cannot be 
> entirely mechanical. I don't think there are disturbance, only 
> entanglement. The laws of big numbers justifies the appearance of 
> irreversibility and collapse, but that never happens. Eventually, the wave 
> itself arises from number's incompleteness self-reflected (you need yo 
> study my papers to get this).
>
>
>
>
>
>
> Given that an optical photon is about .1eV in 

Re: Equivalence Principle and Einstein Field Equations

[agrayson2000]

On Sunday, December 17, 2017 at 10:39:18 PM UTC, agrays...@gmail.com wrote:
>
>
>
> On Sunday, December 17, 2017 at 12:21:27 AM UTC, Brent wrote:
>>
>>
>>
>> On 12/16/2017 2:59 PM, agrays...@gmail.com wrote:
>>
>> There's a problem applying SR in this situation because neither the 
>> ground or orbiting clock is an inertial frame.AG
>>
>>
>> An orbiting clock is in an inertial frame.  An inertial frame is just one 
>> in which no forces are acting (and gravity is not a force) so that it moves 
>> with constant momentum along a geodesic.  Although it's convenient for 
>> engineering calculations, from a fundamental veiwpoint there is no separate 
>> special relativity and general relativity and no separate clock 
>> corrections.  General is just special relativity in curved spacetime.  So 
>> clocks measure the 4-space interval along their path - whether that path is 
>> geodesic (i.e. inertial) or accelerated.
>>
>
> *Interesting way to look at it. So free falling in a gravity field is an 
> extension of SR. But the thing I find puzzling is that in GR the curvature 
> of space-time is caused by the presence of mass, yet I can draw the path of 
> an accelerated body as necessarily a curve in a space-time diagram. I am 
> having trouble resolving these different sources of curvature. AG*
>

*Einstein must have figured that since gravity produces an acceleration 
field, and accelerating test particles move along curved paths in 
space-time, he could replace acceleration by inertial paths in a space-time 
curved by the presence of mass-energy. But now, when comparing test 
particles moving along different paths in space-time, he couldn't use the 
Lorentz transformation because the relative velocities of the frames are 
not necessarily constant. So how did he propose to find the correct 
transformation equations, and what are they? And what were the laws of 
physics, in this case gravity, that had to be invariant? AG*

>
>
>> Brent
>>
>

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