Re: doesn't dark matter falsify general relativity?

[LizR]

I think I'll call it Relativi-stuck cosmology.


On 9 December 2013 13:22, LizR  wrote:

> I'm working on a theory that galaxies are held together by duct tape and
> superglue.
>
> It's proving a little tricky. Obviously the tape has to be arranged so the
> dark side is facing towards us...
>
>
>

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Re: doesn't dark matter falsify general relativity?

[LizR]

I'm working on a theory that galaxies are held together by duct tape and
superglue.

It's proving a little tricky. Obviously the tape has to be arranged so the
dark side is facing towards us...

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Re: doesn't dark matter falsify general relativity?

[Bruno Marchal]

On 07 Dec 2013, at 23:58, John Mikes wrote:


Telmo asked:

Honest question: isn't "dark matter" a fancy name for failed  
predictions?


I would not be so rude  - just call it an ingenious way to save our  
scientific face in so far developed conventional science.
Then it required 'dark energy' in the dark minds.And ALL had been  
justified by the theories to be justified.



I don't think we can, "justify" our theories. We can feel happy to get  
them, happy to see them working for a while, and we can be doubly  
happy when they are shown wrong, as this means that we will learn  
something.


Dark matter is rather sadly amazing in that respect.

God:   - what are the news?
God's engineer:   -  I am afraid humans have found that galaxies  
structures is inconsistent with the matter they can see!

God:- Gosh! What can we do?
God's engineer:- we can add invisible matter, perhaps.
God:- do that! excellent idea, they will see nothing
God's engineer:- Hmm, they will see it indirectly, through  
lenticular structure, and galaxies nice behaviors,

God:- do we need a lot of them?
God's engineer:- well, 90% of matter needs to be made of that  
invisible stuff ...

God:- damned!shhh . (depression).

;)

Bruno







John M


On Fri, Nov 29, 2013 at 6:05 AM, Telmo Menezes  
 wrote:
On Wed, Nov 27, 2013 at 5:03 PM, Jesse Mazer   
wrote:
> Dark matter behaves pretty convincingly like large clumps of  
matter that,
> aside from not interacting with normal matter via non- 
gravitational forces,
> obeys the same sort of dynamical laws as any other form of matter,  
see the
> following for a good quick summary (note particularly the stuff  
about the
> colliding galaxy clusters whose dark matter halos seemed to  
"outshoot" the
> position of the visible clusters themselves, since the visible  
matter like
> stars is slowed down via friction with gas and dust during the  
collision,
> but friction is an electromagnetic interaction so dark matter  
should be

> impervious to it):
>
> 
http://scienceblogs.com/startswithabang/2010/06/24/convincing-a-young-scientist-t/

Thanks Jesse, very nice article.

>
> On Wed, Nov 27, 2013 at 7:40 AM, Telmo Menezes >

> wrote:
>>
>> Hi all,
>>
>> Honest question: isn't "dark matter" a fancy name for failed  
predictions?

>>
>> Cheers,
>> Telmo.
>>
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http://iridia.ulb.ac.be/~marchal/



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Re: doesn't dark matter falsify general relativity?

[LizR]

On 8 December 2013 11:58, John Mikes  wrote:

> Telmo asked:
>
> *Honest question: isn't "dark matter" a fancy name for failed predictions?*
>
> *I would not be so rude * - just call it an ingenious way to save our
> scientific face in so far developed conventional science.
> Then it required 'dark energy' in the dark minds.And ALL had been
> justified by the theories to be justified.
> John M
>
> We shouldn't be surprised there is stuff out there we can't see.
Observation has already revealed a whole bunch of stuff we couldn't detect
as little as a century ago, what are the chances we can see the whole
Hubble Schmeer yet?

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Re: doesn't dark matter falsify general relativity?

[John Mikes]

Telmo asked:

*Honest question: isn't "dark matter" a fancy name for failed predictions?*

*I would not be so rude * - just call it an ingenious way to save our
scientific face in so far developed conventional science.
Then it required 'dark energy' in the dark minds.And ALL had been justified
by the theories to be justified.
John M


On Fri, Nov 29, 2013 at 6:05 AM, Telmo Menezes wrote:

> On Wed, Nov 27, 2013 at 5:03 PM, Jesse Mazer  wrote:
> > Dark matter behaves pretty convincingly like large clumps of matter that,
> > aside from not interacting with normal matter via non-gravitational
> forces,
> > obeys the same sort of dynamical laws as any other form of matter, see
> the
> > following for a good quick summary (note particularly the stuff about the
> > colliding galaxy clusters whose dark matter halos seemed to "outshoot"
> the
> > position of the visible clusters themselves, since the visible matter
> like
> > stars is slowed down via friction with gas and dust during the collision,
> > but friction is an electromagnetic interaction so dark matter should be
> > impervious to it):
> >
> >
> http://scienceblogs.com/startswithabang/2010/06/24/convincing-a-young-scientist-t/
>
> Thanks Jesse, very nice article.
>
> >
> > On Wed, Nov 27, 2013 at 7:40 AM, Telmo Menezes 
> > wrote:
> >>
> >> Hi all,
> >>
> >> Honest question: isn't "dark matter" a fancy name for failed
> predictions?
> >>
> >> Cheers,
> >> Telmo.
> >>
> >> --
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Re: doesn't dark matter falsify general relativity?

[John Clark]

On Fri, Dec 6, 2013 at 5:28 PM, LizR  wrote:

>> If you were falling back first into a Black Hole things that were behind
>> you would start to look as if they were ahead of you, and as you got very
>> close to the event horizon all the light from the entire external universe
>> would be coming to you from a small disk directly in front of you. When you
>> actually crossed the event horizon (the point of no return) the diameter of
>> that disk would shrink to zero and you'd be forever cutoff from the
>> universe you knew. If the Black Hole were large enough you could still be
>> alive when you crossed the event horizon, although a few seconds later
>> tidal forces would rip you apart through spaghettification[...] at the
>> event horizon of one of Einstein's Black Holes, even if the gravity was
>> only 1g, you could never escape the Black Hole and return to Earth no
>> matter how powerful your rocket is; on the surface of Michell's dark star
>> even if it was a billion g you could escape if your rocket was powerful
>> enough (assuming a billion g didn't prove harmful to your health).
>>
>
> > it's a fascinating concept.


Yes.

> What a shame it can't happen in the real world.
>

How do you figure that?

  John K Clark

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Re: doesn't dark matter falsify general relativity?

[LizR]

It's a fascinating concept. What a shame it can't happen in the real world.

On 7 December 2013 07:42, John Clark  wrote:

>
> On Thu, Dec 5, 2013 at 8:11 PM, LizR  wrote:
>
> > Ah yes I've heard that the gravity at the event horizon can be as weak
>> as you like with a suitably large hole - that you might not even realise
>> you'd crossed it
>>
>
> Yes.
>
> > though surely you'd get some optical effects?
>>
>
> If you were falling back first into a Black Hole things that were behind
> you would start to look as if they were ahead of you, and as you got very
> close to the event horizon all the light from the entire external universe
> would be coming to you from a small disk directly in front of you. When you
> actually crossed the event horizon (the point of no return) the diameter of
> that disk would shrink to zero and you'd be forever cutoff from the
> universe you knew. If the Black Hole were large enough you could still be
> alive when you crossed the event horizon, although a few seconds later
> tidal forces would rip you apart through spaghettification
>
> > So the Michell star is effectively like a solid version of a black
>> hole's event horizon.
>>
>
> It's more than that, at the event horizon of one of Einstein's Black
> Holes, even if the gravity was only 1g, you could never escape the Black
> Hole and return to Earth no matter how powerful your rocket is; on the
> surface of Michell's dark star even if it was a billion g you could escape
> if your rocket was powerful enough (assuming a billion g didn't prove
> harmful to your health).
>
>   John K Clark
>

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Re: doesn't dark matter falsify general relativity?

[John Clark]

On Thu, Dec 5, 2013 at 8:11 PM, LizR  wrote:

> Ah yes I've heard that the gravity at the event horizon can be as weak as
> you like with a suitably large hole - that you might not even realise you'd
> crossed it
>

Yes.

> though surely you'd get some optical effects?
>

If you were falling back first into a Black Hole things that were behind
you would start to look as if they were ahead of you, and as you got very
close to the event horizon all the light from the entire external universe
would be coming to you from a small disk directly in front of you. When you
actually crossed the event horizon (the point of no return) the diameter of
that disk would shrink to zero and you'd be forever cutoff from the
universe you knew. If the Black Hole were large enough you could still be
alive when you crossed the event horizon, although a few seconds later
tidal forces would rip you apart through spaghettification

> So the Michell star is effectively like a solid version of a black hole's
> event horizon.
>

It's more than that, at the event horizon of one of Einstein's Black Holes,
even if the gravity was only 1g, you could never escape the Black Hole and
return to Earth no matter how powerful your rocket is; on the surface of
Michell's dark star even if it was a billion g you could escape if your
rocket was powerful enough (assuming a billion g didn't prove harmful to
your health).

  John K Clark

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Re: doesn't dark matter falsify general relativity?

[LizR]

On 6 December 2013 03:00, John Clark  wrote:

> On Wed, Dec 4, 2013 at 8:12 PM, LizR  wrote:
>
> >> The earliest reference I can find is 1783 by John Michell, he  called
>>> them "dark stars", however it had very different properties from  a modern
>>> Black Hole. If I was far from one of Michell's Newtonian dark stars I could
>>> not see it, but unlike a real Black Hole, I could obtain a picture of it
>>> and print it in the newspaper, I'd just have to get closer in a powerful
>>> spaceship. I could even land on the classical dark star, get a sample of it
>>> and then return it to Earth, that sort of thing would be impossible with a
>>> real Einsteinian Black Hole.
>>>
>>
>> > That's the one. It was used in a story by Brian Aldiss, I guess before
>> black holes became widely known about in SF circles (which was probably
>> thanks to Larry Niven). Of course one could only "land" on it if one could
>> withstand the gravity,
>>
>
> If it was large enough the surface gravity on one of Michell's "dark
> stars" could be a earth like 1g or even less. The escape velocity from the
> surface of a object depends on BOTH its surface gravity and how big the
> object is because that determines how fast the gravity weakens with
> distance from the surface, with big objects even a long way away the
> gravity is almost as strong as it is on the surface.  Actually if it were
> big enough even with Einstein's Black Hole the gravity at the event horizon
> could be 1g, although after passing that point of no return you would find
> the gravity increasing continually until it reached infinity at the
> singularity at the center of the hole.
>

Ah yes I've heard that the gravity at the event horizon can be as weak as
you like with a suitably large hole - that you might not even realise you'd
crossed it (though surely you'd get some optical effects?) So the Michell
star is effectively like a solid version of a black hole's event horizon.
If that makes sense.

>
> > and only take off if one could travel faster than light
>>
>
> No, a continuously thrusting rocket could escape from one of Michell's
> "dark stars" as slowly as you'd like just like you can from the Earth, but
> not so with Einstein's Black Hole, from that there is no way out.
>

I suppose one could have a space elevator or whatever and just climb gently
out of the gravity well.That's very interesting. It makes me rather sad
that such objects can't exist, because they'd make for some interesting
fiction, and maybe fact.

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Re: doesn't dark matter falsify general relativity?

[John Clark]

On Wed, Dec 4, 2013 at 8:12 PM, LizR  wrote:

>> The earliest reference I can find is 1783 by John Michell, he  called
>> them "dark stars", however it had very different properties from  a modern
>> Black Hole. If I was far from one of Michell's Newtonian dark stars I could
>> not see it, but unlike a real Black Hole, I could obtain a picture of it
>> and print it in the newspaper, I'd just have to get closer in a powerful
>> spaceship. I could even land on the classical dark star, get a sample of it
>> and then return it to Earth, that sort of thing would be impossible with a
>> real Einsteinian Black Hole.
>>
>
> > That's the one. It was used in a story by Brian Aldiss, I guess before
> black holes became widely known about in SF circles (which was probably
> thanks to Larry Niven). Of course one could only "land" on it if one could
> withstand the gravity,
>

If it was large enough the surface gravity on one of Michell's "dark stars"
could be a earth like 1g or even less. The escape velocity from the surface
of a object depends on BOTH its surface gravity and how big the object is
because that determines how fast the gravity weakens with distance from the
surface, with big objects even a long way away the gravity is almost as
strong as it is on the surface.  Actually if it were big enough even with
Einstein's Black Hole the gravity at the event horizon could be 1g,
although after passing that point of no return you would find the gravity
increasing continually until it reached infinity at the singularity at the
center of the hole.

> and only take off if one could travel faster than light
>

No, a continuously thrusting rocket could escape from one of Michell's
"dark stars" as slowly as you'd like just like you can from the Earth, but
not so with Einstein's Black Hole, from that there is no way out.

  John K Clark

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Re: doesn't dark matter falsify general relativity?

[LizR]

On 5 December 2013 06:58, John Clark  wrote:

> On Mon, Dec 2, 2013 at 4:14 PM, LizR  wrote:
>
>>
>> > the 1919 eclipse data is actually somewhat equivocal, despite
>> catapulting Einstein to fame.
>>
>
> Back then the measurement was made right at the limit of what was possible
> with 1919 technology, since then it has been repeated many times with
> vastly greater precision and Einstein has always passed the test with
> flying colors.
>

That's right, yes. Indeed the most accurate measurement ever made is, I
believe, a test of GR involving gravity waves from a binary neutron star.
My point was that the eclipse result wasn't - apparently - quite as cut and
dried as it was presented, but the person who made it (was that Eddington?)
was keen to show Einstein correct.

>
>
>> > someone predicted black holes way before Einstein, too, on the basis of
>> Newtonian gravity and the measurement of c - although without realising the
>> full implications ... Mitchell???).
>>
>
> The earliest reference I can find is 1783 by John Michell, he  called them
> "dark stars", however it had very different properties from  a modern Black
> Hole. If I was far from one of Michell's Newtonian dark stars I could not
> see it, but unlike a real Black Hole, I could obtain a picture of it and
> print it in the newspaper, I'd just have to get closer in a powerful
> spaceship. I could even land on the classical dark star, get a sample of it
> and then return it to Earth, that sort of thing would be impossible with a
> real Einsteinian Black Hole.
>

That's the one. It was used in a story by Brian Aldiss, I guess before
black holes became widely known about in SF circles (which was probably
thanks to Larry Niven). Of course one could only "land" on it if one could
withstand the gravity, and only take off if one could travel faster than
light - but although those would have been ridiculous goals in Newtonian
theory, they weren't considered physically impossible.

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Re: doesn't dark matter falsify general relativity?

[John Clark]

On Mon, Dec 2, 2013 at 4:14 PM, LizR  wrote:

>
> > the 1919 eclipse data is actually somewhat equivocal, despite
> catapulting Einstein to fame.
>

Back then the measurement was made right at the limit of what was possible
with 1919 technology, since then it has been repeated many times with
vastly greater precision and Einstein has always passed the test with
flying colors.


> > someone predicted black holes way before Einstein, too, on the basis of
> Newtonian gravity and the measurement of c - although without realising the
> full implications ... Mitchell???).
>

The earliest reference I can find is 1783 by John Michell, he  called them
"dark stars", however it had very different properties from  a modern Black
Hole. If I was far from one of Michell's Newtonian dark stars I could not
see it, but unlike a real Black Hole, I could obtain a picture of it and
print it in the newspaper, I'd just have to get closer in a powerful
spaceship. I could even land on the classical dark star, get a sample of it
and then return it to Earth, that sort of thing would be impossible with a
real Einsteinian Black Hole.

  John K Clark

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Re: doesn't dark matter falsify general relativity?

[LizR]

On 3 December 2013 19:46, meekerdb  wrote:

We were both a little drunk, but he was serious.  I asked if the blob of
> metal had been tracked in orbit?  Zwicky said it was too small to track by
> radar.  So then I asked how they knew it entered orbit.  He said they knew
> because telemetry from the second stage rocket showed that it had fired the
> shaped charge at the right altitude and right direction.
>
> I had not recalled this for many years; the party was in 1963.  Consulting
> the internet (which remembers everything, many of which actually happened)
> I find that Zwicky wrote a paper about these experiments which differs
> somewhat from my recollection.
> http://calteches.library.caltech.edu/1801/1/zwicky.pdf
>

 That is seriously impressive, even if it was slightly after Sputnik as it
turns out, he was still first to launch something at above escape velocity,
so those pellets are presumably still orbiting the Sun.

PS Another 50th anniversary (of your party). They are coming thick and fast
at the moment, 1963 was a rather momentous year it seems.

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Re: doesn't dark matter falsify general relativity?

[meekerdb]

On 12/2/2013 10:19 PM, LizR wrote:
On 3 December 2013 11:55, meekerdb mailto:meeke...@verizon.net>> 
wrote:


On 12/2/2013 1:14 PM, LizR wrote:

On 2 December 2013 20:14, meekerdb mailto:meeke...@verizon.net>> wrote:

On 12/1/2013 7:35 PM, LizR wrote:

On 2 December 2013 16:16, Richard Ruquist mailto:yann...@gmail.com>> wrote:

MOND is an alternative explanation that replaces Dark Matter by 
modifying
gravity.


Yes (hence the flippant remark about bolt on extras)

Dark Matter results when gravity is not modified. (pure Newtonian)


Or rather Einsteinian, I don't think Newtonian gravity predicts 
gravitational
lensing?


Sure it does, but only half as strong as GR.

Ah yes, that's right. I believe that's why the 1919 eclipse data is actually
somewhat equivocal, despite catapulting Einstein to fame. (And someone 
predicted
black holes way before Einstein, too, on the basis of Newtonian gravity and 
the
measurement of c - although without realising the full implications ... 
Mitchell???).

Mind you, I think my correction above is still pertinent - that is, it's 
still
truer to say that "dark matter is what results when gravity is not modified 
(pure
/Einsteinian/)".


Dark matter would be implied by the same observations even assuming 
Newtonian
gravity.  Just the amount would be different.  I don't know if Fritz Zwicky 
even
used relativistic calculations of rotation curves of galaxies to infer dark 
matter -
it wouldn't have been necessary since the motions are not that fast.


OK.


Incidentally I met Zwicky at a party once and he regalled me with the story 
of how
he and a NACA team had actually beaten the Russians into space by launching 
an
artificial satellite *before* Sputnik.  When I expressed surprise that I 
had never
heard of this satellite, he explained that it was launched from a B-50 
flying at
50kft over the equator using a two stage rocket.  When the second stage 
reached it's
apogee, it fired a shaped charge which sent a molten mass of metal into 
orbit around
the Earth.

Seriously?!


We were both a little drunk, but he was serious.  I asked if the blob of metal had been 
tracked in orbit?  Zwicky said it was too small to track by radar.  So then I asked how 
they knew it entered orbit.  He said they knew because telemetry from the second stage 
rocket showed that it had fired the shaped charge at the right altitude and right direction.


I had not recalled this for many years; the party was in 1963. Consulting the internet 
(which remembers everything, many of which actually happened) I find that Zwicky wrote a 
paper about these experiments which differs somewhat from my recollection. 
http://calteches.library.caltech.edu/1801/1/zwicky.pdf


Brent

Brent

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Re: doesn't dark matter falsify general relativity?

[LizR]

On 3 December 2013 11:55, meekerdb  wrote:

>  On 12/2/2013 1:14 PM, LizR wrote:
>
>  On 2 December 2013 20:14, meekerdb  wrote:
>
>>  On 12/1/2013 7:35 PM, LizR wrote:
>>
>>  On 2 December 2013 16:16, Richard Ruquist  wrote:
>>
>>> MOND is an alternative explanation that replaces Dark Matter by
>>> modifying gravity.
>>>
>>
>>  Yes (hence the flippant remark about bolt on extras)
>>
>>
>>>  Dark Matter results when gravity is not modified. (pure Newtonian)
>>>
>>
>>  Or rather Einsteinian, I don't think Newtonian gravity predicts
>> gravitational lensing?
>>
>>
>>  Sure it does, but only half as strong as GR.
>>
>>  Ah yes, that's right. I believe that's why the 1919 eclipse data is
> actually somewhat equivocal, despite catapulting Einstein to fame. (And
> someone predicted black holes way before Einstein, too, on the basis of
> Newtonian gravity and the measurement of c - although without realising the
> full implications ... Mitchell???).
>
>  Mind you, I think my correction above is still pertinent - that is, it's
> still truer to say that "dark matter is what results when gravity is not
> modified (pure *Einsteinian*)".
>
>
> Dark matter would be implied by the same observations even assuming
> Newtonian gravity.  Just the amount would be different.  I don't know if
> Fritz Zwicky even used relativistic calculations of rotation curves of
> galaxies to infer dark matter - it wouldn't have been necessary since the
> motions are not that fast.
>

OK.

>
> Incidentally I met Zwicky at a party once and he regalled me with the
> story of how he and a NACA team had actually beaten the Russians into space
> by launching an artificial satellite *before* Sputnik.  When I expressed
> surprise that I had never heard of this satellite, he explained that it was
> launched from a B-50 flying at 50kft over the equator using a two stage
> rocket.  When the second stage reached it's apogee, it fired a shaped
> charge which sent a molten mass of metal into orbit around the Earth.
>
> Seriously?!

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Re: doesn't dark matter falsify general relativity?

[meekerdb]

On 12/2/2013 1:14 PM, LizR wrote:
On 2 December 2013 20:14, meekerdb mailto:meeke...@verizon.net>> 
wrote:


On 12/1/2013 7:35 PM, LizR wrote:

On 2 December 2013 16:16, Richard Ruquist mailto:yann...@gmail.com>> wrote:

MOND is an alternative explanation that replaces Dark Matter by 
modifying gravity.


Yes (hence the flippant remark about bolt on extras)

Dark Matter results when gravity is not modified. (pure Newtonian)


Or rather Einsteinian, I don't think Newtonian gravity predicts 
gravitational lensing?


Sure it does, but only half as strong as GR.

Ah yes, that's right. I believe that's why the 1919 eclipse data is actually somewhat 
equivocal, despite catapulting Einstein to fame. (And someone predicted black holes way 
before Einstein, too, on the basis of Newtonian gravity and the measurement of c - 
although without realising the full implications ... Mitchell???).


Mind you, I think my correction above is still pertinent - that is, it's still truer to 
say that "dark matter is what results when gravity is not modified (pure /Einsteinian/)".


Dark matter would be implied by the same observations even assuming Newtonian gravity.  
Just the amount would be different.  I don't know if Fritz Zwicky even used relativistic 
calculations of rotation curves of galaxies to infer dark matter - it wouldn't have been 
necessary since the motions are not that fast.


Incidentally I met Zwicky at a party once and he regalled me with the story of how he and 
a NACA team had actually beaten the Russians into space by launching an artificial 
satellite *before* Sputnik. When I expressed surprise that I had never heard of this 
satellite, he explained that it was launched from a B-50 flying at 50kft over the equator 
using a two stage rocket.  When the second stage reached it's apogee, it fired a shaped 
charge which sent a molten mass of metal into orbit around the Earth.


Brent

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Re: doesn't dark matter falsify general relativity?

[LizR]

On 2 December 2013 20:14, meekerdb  wrote:

>  On 12/1/2013 7:35 PM, LizR wrote:
>
>  On 2 December 2013 16:16, Richard Ruquist  wrote:
>
>> MOND is an alternative explanation that replaces Dark Matter by modifying
>> gravity.
>>
>
>  Yes (hence the flippant remark about bolt on extras)
>
>
>>  Dark Matter results when gravity is not modified. (pure Newtonian)
>>
>
>  Or rather Einsteinian, I don't think Newtonian gravity predicts
> gravitational lensing?
>
>
> Sure it does, but only half as strong as GR.
>
> Ah yes, that's right. I believe that's why the 1919 eclipse data is
actually somewhat equivocal, despite catapulting Einstein to fame. (And
someone predicted black holes way before Einstein, too, on the basis of
Newtonian gravity and the measurement of c - although without realising the
full implications ... Mitchell???).

Mind you, I think my correction above is still pertinent - that is, it's
still truer to say that "dark matter is what results when gravity is not
modified (pure *Einsteinian*)".

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Re: doesn't dark matter falsify general relativity?

[meekerdb]

On 12/1/2013 7:35 PM, LizR wrote:
On 2 December 2013 16:16, Richard Ruquist mailto:yann...@gmail.com>> 
wrote:


MOND is an alternative explanation that replaces Dark Matter by modifying 
gravity.


Yes (hence the flippant remark about bolt on extras)

Dark Matter results when gravity is not modified. (pure Newtonian)


Or rather Einsteinian, I don't think Newtonian gravity predicts gravitational 
lensing?


Sure it does, but only half as strong as GR.

Brent



IMO John Moffat has a much better mod-gravity theory
http://arxiv.org/pdf/gr-qc/0506021.pdf


That VSL idea sounds familiar, I may have heard of that before. I would imagine it 
solves the horizon problem and does away with the need for inflation in the early 
universe; if he can also sort our dark matter and dark energy he's doing rather well, 
all he needs after that is an "acid test" that will distinguish his theory from GR (much 
as the 1919 eclipse was supposed to have been the acid test for GR vs Newtonian gravity) 
and he can claim his Nobel (if he hasn't got one already).


In fact, I'm fairly sure we have the Magueijo book somewhere. (When do I get my 
ansible?)


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Re: doesn't dark matter falsify general relativity?

[Richard Ruquist]

Moffat even does away with renormalization.
The acid test was to be the fine structure constant being time dependent.
But that was not repeatable for a south hemisphere telescope whose name I
forget.

The two Keck Telescopes were built at Litton ITEK in Lexington, MA where I
worked for a few years.
They had cornered the market for spaceborne spy satellites. But after the
Berlin Wall came down the US govt decided they did not need ITEK any more
and ITEK was sold to Perkin Elmer who screwed up the Hubble Space
telescope. Most of us lost our jobs instead of moving to Connecticut. It
was the last physics research job I had.


On Sun, Dec 1, 2013 at 10:35 PM, LizR  wrote:

> On 2 December 2013 16:16, Richard Ruquist  wrote:
>
>> MOND is an alternative explanation that replaces Dark Matter by modifying
>> gravity.
>>
>
> Yes (hence the flippant remark about bolt on extras)
>
>
>> Dark Matter results when gravity is not modified. (pure Newtonian)
>>
>
> Or rather Einsteinian, I don't think Newtonian gravity predicts
> gravitational lensing?
>
>>
>> IMO John Moffat has a much better mod-gravity theory
>> http://arxiv.org/pdf/gr-qc/0506021.pdf
>>
>
> That VSL idea sounds familiar, I may have heard of that before. I would
> imagine it solves the horizon problem and does away with the need for
> inflation in the early universe; if he can also sort our dark matter and
> dark energy he's doing rather well, all he needs after that is an "acid
> test" that will distinguish his theory from GR (much as the 1919 eclipse
> was supposed to have been the acid test for GR vs Newtonian gravity) and he
> can claim his Nobel (if he hasn't got one already).
>
> In fact, I'm fairly sure we have the Magueijo book somewhere. (When do I
> get my ansible?)
>
>>
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Re: doesn't dark matter falsify general relativity?

[LizR]

On 2 December 2013 16:16, Richard Ruquist  wrote:

> MOND is an alternative explanation that replaces Dark Matter by modifying
> gravity.
>

Yes (hence the flippant remark about bolt on extras)


> Dark Matter results when gravity is not modified. (pure Newtonian)
>

Or rather Einsteinian, I don't think Newtonian gravity predicts
gravitational lensing?

>
> IMO John Moffat has a much better mod-gravity theory
> http://arxiv.org/pdf/gr-qc/0506021.pdf
>

That VSL idea sounds familiar, I may have heard of that before. I would
imagine it solves the horizon problem and does away with the need for
inflation in the early universe; if he can also sort our dark matter and
dark energy he's doing rather well, all he needs after that is an "acid
test" that will distinguish his theory from GR (much as the 1919 eclipse
was supposed to have been the acid test for GR vs Newtonian gravity) and he
can claim his Nobel (if he hasn't got one already).

In fact, I'm fairly sure we have the Magueijo book somewhere. (When do I
get my ansible?)

>

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Re: doesn't dark matter falsify general relativity?

[Richard Ruquist]

MOND is an alternative explanation that replaces Dark Matter by modifying
gravity.
Dark Matter results when gravity is not modified. (pure Newtonian)

IMO John Moffat has a much better mod-gravity theory
http://arxiv.org/pdf/gr-qc/0506021.pdf

wiki-Moffat: He proposes a variable speed of
light approach
to cosmological  problems,
which posits that *G */
*c* is constant through time, but *G* and *c* separately have not been.in
the early universe, in which the speed of light was 1030 times faster than
its current value.

Richard: That would say that the fine structure constant was different in
the early universe, which agrees with observations of the Keck telescope.
However, more recent observations in the southern hemisphere indicates the
the fine structure constant varies monotonically north to south and not as
a function of time. I have used those observations to hypothesize that the
Calabi-Yau compact space particles are numerable and a basis for
computationalism in my string cosmology papers. But he has done much more-
read his wiki.

On a personal note John Moffat was a consultant one summer in the MIT
Lincoln Lab group that I worked in in the late 1960s.
But I am not sure it's the same John Moffat.



On Sun, Dec 1, 2013 at 9:44 PM, LizR  wrote:

> I should have said that by ad hoc I mean with no, or little,  theoretical
> justification. That is, adjusting the threoy to fit the data, but with for
> no compelling theoretical justification.
>
>
> On 2 December 2013 15:42, LizR  wrote:
>
>> Ad hoc modifications to our existing theories. Although it looks like
>> it's actually bolt-on extras to Newtonian gravitation...
>>
>> http://en.wikipedia.org/wiki/MOND
>>
>>
>>
>> On 2 December 2013 14:33, Richard Ruquist  wrote:
>>
>>> Can you explain what you mean by 'bolt-on extras to GR'?
>>>
>>>
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Re: doesn't dark matter falsify general relativity?

[LizR]

I should have said that by ad hoc I mean with no, or little,  theoretical
justification. That is, adjusting the threoy to fit the data, but with for
no compelling theoretical justification.


On 2 December 2013 15:42, LizR  wrote:

> Ad hoc modifications to our existing theories. Although it looks like it's
> actually bolt-on extras to Newtonian gravitation...
>
> http://en.wikipedia.org/wiki/MOND
>
>
>
> On 2 December 2013 14:33, Richard Ruquist  wrote:
>
>> Can you explain what you mean by 'bolt-on extras to GR'?
>>
>>

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Re: doesn't dark matter falsify general relativity?

[LizR]

Ad hoc modifications to our existing theories. Although it looks like it's
actually bolt-on extras to Newtonian gravitation...

http://en.wikipedia.org/wiki/MOND



On 2 December 2013 14:33, Richard Ruquist  wrote:

> Can you explain what you mean by 'bolt-on extras to GR'?
>
>

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Re: doesn't dark matter falsify general relativity?

[Richard Ruquist]

Can you explain what you mean by 'bolt-on extras to GR'?


On Sun, Dec 1, 2013 at 7:18 PM, LizR  wrote:

> Thanks, that's an impressive list. I'd be rather surprised if "bolt-on
> extras to GR" can explain all those.
>
>
> On 2 December 2013 12:43, Richard Ruquist  wrote:
>
>> Liz,
>>
>> There are 7 other repeatable observations explained by dark matter. From
>> wiki-dark matter
>>
>>
>>- 3.1 Galaxy rotation 
>> curves
>>- 3.2 Velocity dispersions of 
>> galaxies
>>- 3.3 Galaxy clusters and gravitational 
>> lensing
>>- 3.4 Cosmic microwave 
>> background
>>- 3.5 Sky surveys and baryon acoustic 
>> oscillations
>>- 3.6 Type Ia supernovae distance 
>> measurements
>>- 3.7 Lyman-alpha 
>> forest
>>- 3.8 Structure 
>> formation
>>
>>
>>
>> On Sun, Dec 1, 2013 at 4:58 PM, LizR  wrote:
>>
>>> On 30 November 2013 12:04, Telmo Menezes  wrote:
>>>

 Thanks for the explanations. Ok, I think I now understand why dark
 matter is the best hypothesis.

 It is, to date. Neverthless, you would have been quite correct had it
>>> been the anomaly in the orbit of Mercury that you were trying to explain,
>>> rather than the anomalous rotation of galaxies observed in 1933 by Fritz
>>> Zwicky. Pre-Einstein, various theories were advanced to explain the
>>> anomalous perihelion advance of Mercury (relative to what Newtonian
>>> gravitation predicted it should have been) including "hidden matter" - an
>>> undetected planet (called Vulcan, as Trekkies and Dr Who fans will
>>> appreciate) and an odd mass distribution inside the Sun.
>>>
>>> But in that case, it turned out that the best answer WAS to modify
>>> gravity.
>>>
>>> So far DM has remained the top explanation even as more phenomena
>>> involving it have been discovered (garvitational lensing for example). Some
>>> of its characteristics are now fairly well measured; its nature remains
>>> unexplained... which makes life interesting for particle physicists and
>>> cosmologists.
>>>
>>>  --
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>>
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Re: doesn't dark matter falsify general relativity?

[LizR]

Thanks, that's an impressive list. I'd be rather surprised if "bolt-on
extras to GR" can explain all those.


On 2 December 2013 12:43, Richard Ruquist  wrote:

> Liz,
>
> There are 7 other repeatable observations explained by dark matter. From
> wiki-dark matter
>
>
>- 3.1 Galaxy rotation 
> curves
>- 3.2 Velocity dispersions of 
> galaxies
>- 3.3 Galaxy clusters and gravitational 
> lensing
>- 3.4 Cosmic microwave 
> background
>- 3.5 Sky surveys and baryon acoustic 
> oscillations
>- 3.6 Type Ia supernovae distance 
> measurements
>- 3.7 Lyman-alpha 
> forest
>- 3.8 Structure 
> formation
>
>
>
> On Sun, Dec 1, 2013 at 4:58 PM, LizR  wrote:
>
>> On 30 November 2013 12:04, Telmo Menezes  wrote:
>>
>>>
>>> Thanks for the explanations. Ok, I think I now understand why dark
>>> matter is the best hypothesis.
>>>
>>> It is, to date. Neverthless, you would have been quite correct had it
>> been the anomaly in the orbit of Mercury that you were trying to explain,
>> rather than the anomalous rotation of galaxies observed in 1933 by Fritz
>> Zwicky. Pre-Einstein, various theories were advanced to explain the
>> anomalous perihelion advance of Mercury (relative to what Newtonian
>> gravitation predicted it should have been) including "hidden matter" - an
>> undetected planet (called Vulcan, as Trekkies and Dr Who fans will
>> appreciate) and an odd mass distribution inside the Sun.
>>
>> But in that case, it turned out that the best answer WAS to modify
>> gravity.
>>
>> So far DM has remained the top explanation even as more phenomena
>> involving it have been discovered (garvitational lensing for example). Some
>> of its characteristics are now fairly well measured; its nature remains
>> unexplained... which makes life interesting for particle physicists and
>> cosmologists.
>>
>>  --
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>
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Re: doesn't dark matter falsify general relativity?

[Richard Ruquist]

Liz,

There are 7 other repeatable observations explained by dark matter. From
wiki-dark matter


   - 3.1 Galaxy rotation
curves
   - 3.2 Velocity dispersions of
galaxies
   - 3.3 Galaxy clusters and gravitational
lensing
   - 3.4 Cosmic microwave
background
   - 3.5 Sky surveys and baryon acoustic
oscillations
   - 3.6 Type Ia supernovae distance
measurements
   - 3.7 Lyman-alpha
forest
   - 3.8 Structure
formation



On Sun, Dec 1, 2013 at 4:58 PM, LizR  wrote:

> On 30 November 2013 12:04, Telmo Menezes  wrote:
>
>>
>> Thanks for the explanations. Ok, I think I now understand why dark
>> matter is the best hypothesis.
>>
>> It is, to date. Neverthless, you would have been quite correct had it
> been the anomaly in the orbit of Mercury that you were trying to explain,
> rather than the anomalous rotation of galaxies observed in 1933 by Fritz
> Zwicky. Pre-Einstein, various theories were advanced to explain the
> anomalous perihelion advance of Mercury (relative to what Newtonian
> gravitation predicted it should have been) including "hidden matter" - an
> undetected planet (called Vulcan, as Trekkies and Dr Who fans will
> appreciate) and an odd mass distribution inside the Sun.
>
> But in that case, it turned out that the best answer WAS to modify gravity.
>
> So far DM has remained the top explanation even as more phenomena
> involving it have been discovered (garvitational lensing for example). Some
> of its characteristics are now fairly well measured; its nature remains
> unexplained... which makes life interesting for particle physicists and
> cosmologists.
>
>  --
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Re: doesn't dark matter falsify general relativity?

[LizR]

On 30 November 2013 12:04, Telmo Menezes  wrote:

>
> Thanks for the explanations. Ok, I think I now understand why dark
> matter is the best hypothesis.
>
> It is, to date. Neverthless, you would have been quite correct had it been
the anomaly in the orbit of Mercury that you were trying to explain, rather
than the anomalous rotation of galaxies observed in 1933 by Fritz Zwicky.
Pre-Einstein, various theories were advanced to explain the anomalous
perihelion advance of Mercury (relative to what Newtonian gravitation
predicted it should have been) including "hidden matter" - an undetected
planet (called Vulcan, as Trekkies and Dr Who fans will appreciate) and an
odd mass distribution inside the Sun.

But in that case, it turned out that the best answer WAS to modify gravity.

So far DM has remained the top explanation even as more phenomena involving
it have been discovered (garvitational lensing for example). Some of its
characteristics are now fairly well measured; its nature remains
unexplained... which makes life interesting for particle physicists and
cosmologists.

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Re: doesn't dark matter falsify general relativity?

[Telmo Menezes]

> For years people have tried to modify the law of gravitation so that it is
> consistent with what we see with our telescopes but it just doesn't work. If
> you observe the Bullet Cluster what you see is 2 clusters colliding and the
> regular matter that we can see staying in the center just as we'd expect
> regular matter to do and the Dark Matter (detected by gravitational lensing)
> remained spread out just as you'd expect Dark Matter to do. There is no way
> modifying gravity can explain that.
>
> And in addition, if you tinker with gravity so that galaxies like our own
> Milky Way hold together and behave as they should then galactic clusters
> like the Local group don't behave as we see them do. And if you tinker with
> gravity in another way so that galactic clusters behave as they do in our
> telescopes then individual galaxies don't. But if you invoke Dark Matter
> then everything comes out fine.
>
>   John K Clark

On Fri, Nov 29, 2013 at 10:26 PM, meekerdb  wrote:

> First, that isn't just assumed.  Other theories to explain it have been put
> forward, e.g. modifications of GR.  But so far they have all been
> invalidated by observations, whereas the hypothesis that it is some kind of
> matter that interacts only (or almost only) via gravity has survived an
> increasing variety of observations.
>
>
>> As far
>> as I understand, QM hasn't been reconciled with GR gravity. Isn't this
>> + dark matter a sign that there's something fundamental we don't
>> understand yet?
>
>
> There's certainly somethings we don't understand yet.  Whether dark matter
> is 'fundamental', in the sense that QM and GR are fundamentally in conflict,
> is possible but not supported by any data yet.
>
> Brent

John and Brent,

Thanks for the explanations. Ok, I think I now understand why dark
matter is the best hypothesis.

Cheers
Telmo.

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Re: doesn't dark matter falsify general relativity?

[Richard Ruquist]

My question has nothing to do with modyfying gravity


On Fri, Nov 29, 2013 at 3:58 PM, John Clark  wrote:

> On Fri, Nov 29, 2013 at 3:31 PM, Richard Ruquist wrote:
>
> > Does the Bullet cluster display any of the characteristics expected of a
>> Dark-Matter-less galaxy such as a spinning galaxy blowing apart.?
>>
>
> For years people have tried to modify the law of gravitation so that it is
> consistent with what we see with our telescopes but it just doesn't work.
> If you observe the Bullet Cluster what you see is 2 clusters colliding and
> the regular matter that we can see staying in the center just as we'd
> expect regular matter to do and the Dark Matter (detected by gravitational
> lensing) remained spread out just as you'd expect Dark Matter to do. There
> is no way modifying gravity can explain that.
>
> And in addition, if you tinker with gravity so that galaxies like our own
> Milky Way hold together and behave as they should then galactic clusters
> like the Local group don't behave as we see them do. And if you tinker with
> gravity in another way so that galactic clusters behave as they do in our
> telescopes then individual galaxies don't. But if you invoke Dark Matter
> then everything comes out fine.
>
>   John K Clark
>
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Re: doesn't dark matter falsify general relativity?

[meekerdb]

On 11/29/2013 3:18 AM, Telmo Menezes wrote:

On Fri, Nov 29, 2013 at 4:57 AM, John Clark  wrote:

On Wed, Nov 27, 2013 at 9:07 AM, Telmo Menezes 
wrote:


if GR requires dark matter to work, and if we can't observe dark matter,
doesn't this mean that GR is falsified?


If Dark Matter really isn't there then that would indeed falsify General
Relativity; but the theory that Dark Matter really isn't there is itself
falsified by observations of the Bullet Cluster.

   John K Clark

Thanks John, and also Richard, Brent and Liz.

I know my questions are very naive, but the following occurs to me
(and I'm sure this has been debated to death by physicists): why is it
assumed that this phenomena is caused by some type of matter?


First, that isn't just assumed.  Other theories to explain it have been put forward, e.g. 
modifications of GR.  But so far they have all been invalidated by observations, whereas 
the hypothesis that it is some kind of matter that interacts only (or almost only) via 
gravity has survived an increasing variety of observations.



As far
as I understand, QM hasn't been reconciled with GR gravity. Isn't this
+ dark matter a sign that there's something fundamental we don't
understand yet?


There's certainly somethings we don't understand yet.  Whether dark matter is 
'fundamental', in the sense that QM and GR are fundamentally in conflict, is possible but 
not supported by any data yet.


Brent


Or maybe this is the sense in which "dark matter" is
already used, and I'm worrying too much about the word "matter"...

Telmo.


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Re: doesn't dark matter falsify general relativity?

[John Clark]

On Fri, Nov 29, 2013 at 3:31 PM, Richard Ruquist  wrote:

> Does the Bullet cluster display any of the characteristics expected of a
> Dark-Matter-less galaxy such as a spinning galaxy blowing apart.?
>

For years people have tried to modify the law of gravitation so that it is
consistent with what we see with our telescopes but it just doesn't work.
If you observe the Bullet Cluster what you see is 2 clusters colliding and
the regular matter that we can see staying in the center just as we'd
expect regular matter to do and the Dark Matter (detected by gravitational
lensing) remained spread out just as you'd expect Dark Matter to do. There
is no way modifying gravity can explain that.

And in addition, if you tinker with gravity so that galaxies like our own
Milky Way hold together and behave as they should then galactic clusters
like the Local group don't behave as we see them do. And if you tinker with
gravity in another way so that galactic clusters behave as they do in our
telescopes then individual galaxies don't. But if you invoke Dark Matter
then everything comes out fine.

  John K Clark

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Re: doesn't dark matter falsify general relativity?

[Richard Ruquist]

Does the Bullet cluster display any of the characteristics expected of a
Dark-Matter-less galaxy
such as a spinning galaxy blowing apart.?


On Fri, Nov 29, 2013 at 3:18 PM, John Clark  wrote:

> On Fri, Nov 29, 2013 at 6:18 AM, Telmo Menezes wrote:
>
> > why is it assumed that this phenomena is caused by some type of matter?
>> [...] and I'm worrying too much about the word "matter"...
>>
>
> Observations of the Bullet Cluster indicate that whatever this dark stuff
> is it has inertia and moves much more slowly than light, so it must have a
> rest mass and it must both produce gravity and be effected by it. To a
> physicist anything that has those properties is matter even if it's dark,
> that is to say you can't see it because it is not effected by
> electromagnetic waves.
>
>   John K Clark
>
>
>
>
>
>
>
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Re: doesn't dark matter falsify general relativity?

[John Clark]

On Fri, Nov 29, 2013 at 6:18 AM, Telmo Menezes wrote:

> why is it assumed that this phenomena is caused by some type of matter?
> [...] and I'm worrying too much about the word "matter"...
>

Observations of the Bullet Cluster indicate that whatever this dark stuff
is it has inertia and moves much more slowly than light, so it must have a
rest mass and it must both produce gravity and be effected by it. To a
physicist anything that has those properties is matter even if it's dark,
that is to say you can't see it because it is not effected by
electromagnetic waves.

  John K Clark

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Re: doesn't dark matter falsify general relativity?

[Telmo Menezes]

On Fri, Nov 29, 2013 at 4:57 AM, John Clark  wrote:
>
> On Wed, Nov 27, 2013 at 9:07 AM, Telmo Menezes 
> wrote:
>
>> > if GR requires dark matter to work, and if we can't observe dark matter,
>> > doesn't this mean that GR is falsified?
>
>
> If Dark Matter really isn't there then that would indeed falsify General
> Relativity; but the theory that Dark Matter really isn't there is itself
> falsified by observations of the Bullet Cluster.
>
>   John K Clark

Thanks John, and also Richard, Brent and Liz.

I know my questions are very naive, but the following occurs to me
(and I'm sure this has been debated to death by physicists): why is it
assumed that this phenomena is caused by some type of matter? As far
as I understand, QM hasn't been reconciled with GR gravity. Isn't this
+ dark matter a sign that there's something fundamental we don't
understand yet? Or maybe this is the sense in which "dark matter" is
already used, and I'm worrying too much about the word "matter"...

Telmo.

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Re: doesn't dark matter falsify general relativity?

[Telmo Menezes]

On Wed, Nov 27, 2013 at 5:03 PM, Jesse Mazer  wrote:
> Dark matter behaves pretty convincingly like large clumps of matter that,
> aside from not interacting with normal matter via non-gravitational forces,
> obeys the same sort of dynamical laws as any other form of matter, see the
> following for a good quick summary (note particularly the stuff about the
> colliding galaxy clusters whose dark matter halos seemed to "outshoot" the
> position of the visible clusters themselves, since the visible matter like
> stars is slowed down via friction with gas and dust during the collision,
> but friction is an electromagnetic interaction so dark matter should be
> impervious to it):
>
> http://scienceblogs.com/startswithabang/2010/06/24/convincing-a-young-scientist-t/

Thanks Jesse, very nice article.

>
> On Wed, Nov 27, 2013 at 7:40 AM, Telmo Menezes 
> wrote:
>>
>> Hi all,
>>
>> Honest question: isn't "dark matter" a fancy name for failed predictions?
>>
>> Cheers,
>> Telmo.
>>
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Re: doesn't dark matter falsify general relativity?

[John Clark]

On Wed, Nov 27, 2013 at 9:07 AM, Telmo Menezes wrote:

> if GR requires dark matter to work, and if we can't observe dark matter,
> doesn't this mean that GR is falsified?


If Dark Matter really isn't there then that would indeed falsify General
Relativity; but the theory that Dark Matter really isn't there is itself
falsified by observations of the Bullet Cluster.

  John K Clark

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Re: doesn't dark matter falsify general relativity?

[LizR]

On 28 November 2013 03:07, Telmo Menezes  wrote:

> Thanks. I didn't express myself clearly. What I mean is: if GR
> requires dark matter to work, and if we can't observe dark matter,
> doesn't this mean that GR is falsified? It seems to predict the
> existence of something that is not there...
>
> Only to the extent that beta decay invalidates quantum theory, I would
say. The "least unknowns" approach suggests that GR - observed to be
correct in all situations where it can be measured - is correct, and dark
matter is a form of matter (or at least a source of gravity) that we can't
detect. Or (like the neutrino) that we can't detect yet.

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Re: doesn't dark matter falsify general relativity?

[meekerdb]

On 11/27/2013 4:40 AM, Telmo Menezes wrote:

Hi all,

Honest question: isn't "dark matter" a fancy name for failed predictions?


No.  Although it is dark it can be 'seen' by gravitational lensing and by its effect on 
the motion of luminous matter.


Brent

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Re: doesn't dark matter falsify general relativity?

[Jesse Mazer]

Dark matter behaves pretty convincingly like large clumps of matter that,
aside from not interacting with normal matter via non-gravitational forces,
obeys the same sort of dynamical laws as any other form of matter, see the
following for a good quick summary (note particularly the stuff about the
colliding galaxy clusters whose dark matter halos seemed to "outshoot" the
position of the visible clusters themselves, since the visible matter like
stars is slowed down via friction with gas and dust during the collision,
but friction is an electromagnetic interaction so dark matter should be
impervious to it):

http://scienceblogs.com/startswithabang/2010/06/24/convincing-a-young-scientist-t/


On Wed, Nov 27, 2013 at 7:40 AM, Telmo Menezes wrote:

> Hi all,
>
> Honest question: isn't "dark matter" a fancy name for failed predictions?
>
> Cheers,
> Telmo.
>
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Re: doesn't dark matter falsify general relativity?

[Richard Ruquist]

Telmo Menezes te...@telmomenezes.com
via
 googlegroups.com
9:07 AM (12 minutes ago)
to everything-list
On Wed, Nov 27, 2013 at 3:04 PM, Richard Ruquist  wrote:
> Dark Matter is required for GR to predict that galaxies do not fly apart
> Richard

Hi Richard,

Thanks. I didn't express myself clearly. What I mean is: if GR
requires dark matter to work, and if we can't observe dark matter,
doesn't this mean that GR is falsified? It seems to predict the
existence of something that is not there...

Telmo.

No. Dark matter and energy are clearly there whether or not we know what
particles they are made of.
There are several observations/measurements that indicate that the universe
is flat.
The existence of dark matter and energy is completely consistent with them.


On Wed, Nov 27, 2013 at 9:07 AM, Telmo Menezes wrote:

> On Wed, Nov 27, 2013 at 3:04 PM, Richard Ruquist 
> wrote:
> > Dark Matter is required for GR to predict that galaxies do not fly apart
> > Richard
>
> Hi Richard,
>
> Thanks. I didn't express myself clearly. What I mean is: if GR
> requires dark matter to work, and if we can't observe dark matter,
> doesn't this mean that GR is falsified? It seems to predict the
> existence of something that is not there...
>
> Telmo.
>
> >
> > On Wed, Nov 27, 2013 at 7:40 AM, Telmo Menezes 
> > wrote:
> >>
> >> Hi all,
> >>
> >> Honest question: isn't "dark matter" a fancy name for failed
> predictions?
> >>
> >> Cheers,
> >> Telmo.
> >>
> >> --
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Re: doesn't dark matter falsify general relativity?

[Telmo Menezes]

On Wed, Nov 27, 2013 at 3:04 PM, Richard Ruquist  wrote:
> Dark Matter is required for GR to predict that galaxies do not fly apart
> Richard

Hi Richard,

Thanks. I didn't express myself clearly. What I mean is: if GR
requires dark matter to work, and if we can't observe dark matter,
doesn't this mean that GR is falsified? It seems to predict the
existence of something that is not there...

Telmo.

>
> On Wed, Nov 27, 2013 at 7:40 AM, Telmo Menezes 
> wrote:
>>
>> Hi all,
>>
>> Honest question: isn't "dark matter" a fancy name for failed predictions?
>>
>> Cheers,
>> Telmo.
>>
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Re: doesn't dark matter falsify general relativity?

[Richard Ruquist]

Dark Matter is required for GR to predict that galaxies do not fly apart
Richard


On Wed, Nov 27, 2013 at 7:40 AM, Telmo Menezes wrote:

> Hi all,
>
> Honest question: isn't "dark matter" a fancy name for failed predictions?
>
> Cheers,
> Telmo.
>
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doesn't dark matter falsify general relativity?

[Telmo Menezes]

Hi all,

Honest question: isn't "dark matter" a fancy name for failed predictions?

Cheers,
Telmo.

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