"Bill Hobba" schrieb
"mountain man" wrote
"Bill Hobba" wrote in message
Wrong. GR has yet to find experimental refutation.

Dont you mean GR plus the additional "dark matter"
postulate when considered together have yet to find
experimental refutation?

No. A simple cosmological model based on reasonable assumptions shows the
acceleration should be slowing yet is observed to be accelerating. This
either shows GR or some of the other assumptions that goes into the model
is
false. The assumption that has been found wanting is not GR but that
matter
exists that may be 'exotic' by which is meant it violates the strong
energy
condition - one of the assumptions that goes into the model.

Why not GR?

Dark matter is
supposed to do just that - violate the strong energy condition. Indeed if
inflation is correct the early universe violated the strong energy
condition. One can not claim GR has been refuted when other assumptions
can
also explain it.

In this case, we can never claim GR has been refuted. Because other
explanations can also explain every violation of the Einstein equations
G_mn = T_mn.

If G_mn =/= T_mn we simply have to postulate dark matter as

T_mn^dark = G_mn - T_mn^obs

and the Einstein equation holds again.

Although the strong energy condition is looked upon as
suspect still other assumptions (not GR) could be at fault.

Indeed. But to claim "GR has yet to find experimental refutation"
seems completely unjustified in the current situation with dark matter.

Ilja

Ilja Schmelzer wrote:


Indeed. But to claim "GR has yet to find experimental refutation"
seems completely unjustified in the current situation with dark matter.

Ilja



"Dark Matter" is simply matter that is not emitting
or absorbing photons.... What has that to do with
General Relativity?

Scientists Map Dark Matter, Prove Einstein Right
http://www.space.com/news/cosmic_shear_000512.html

Particle Dark Matter: Evidence, Candidates and Constraints
http://arxiv.org/abs/hep-ph/0404175

"Ilja Schmelzer" wrote in message
...

"Bill Hobba" schrieb
"mountain man" wrote
"Bill Hobba" wrote in message
Wrong. GR has yet to find experimental refutation.

Dont you mean GR plus the additional "dark matter"
postulate when considered together have yet to find
experimental refutation?

No. A simple cosmological model based on reasonable assumptions shows
the
acceleration should be slowing yet is observed to be accelerating. This
either shows GR or some of the other assumptions that goes into the model
is
false. The assumption that has been found wanting is not GR but that
matter
exists that may be 'exotic' by which is meant it violates the strong
energy
condition - one of the assumptions that goes into the model.

Why not GR?

No reason other than general consensus. Please remember the logic of my
argument which is a model that consists of GR. plus the strong energy
condition plus some other assumptions has been experimentally refuted. This
does not imply GR. is incorrect - the strong energy condition for example
may be at fault. Indeed this is the one that most articles I have read look
at rather than GR. This of course does not prove GR. is not at fault - but
it does not prove it is wrong either.


Dark matter is
supposed to do just that - violate the strong energy condition. Indeed
if
inflation is correct the early universe violated the strong energy
condition. One can not claim GR has been refuted when other assumptions
can
also explain it.

In this case, we can never claim GR has been refuted. Because other
explanations can also explain every violation of the Einstein equations
G_mn = T_mn.


I disagree. If, for example, the precession of mercury was not as predicted
or the Pound Rebka experiment was not as predicted GR. would be in serious
trouble.


If G_mn =/= T_mn we simply have to postulate dark matter as

T_mn^dark = G_mn - T_mn^obs

and the Einstein equation holds again.

Sure, but can every other test be explained away so easily? I doubt it.


Although the strong energy condition is looked upon as
suspect still other assumptions (not GR) could be at fault.

Indeed. But to claim "GR has yet to find experimental refutation"
seems completely unjustified in the current situation with dark matter.

I suspect this is a semantic issue. We have yet to find classical phenomena
that refutes GR. By which I mean phenomena that forces us to abandon GER.
because no other reasonable explanation exists - we for example have found
phenomena that refutes Newtonian gravity. Please remember that it is even
not possible to prove the earth is not flat as discussions with flat
earthier will readily demonstrate with their conspiracy type arguments.
However most people would reject such and say we have proof it is not flat
because the other arguments simply do not make sense The same with GR. -
and I detailed above the type of experimental refutation I would accept (and
I suspect most others would also accept) eg wrong precession measurements on
mercury.

Thanks
Bill


Ilja

"Sam Wormley" wrote in message
news:aPXSe.311421$_o.157432@attbi_s71...
Ilja Schmelzer wrote:


Indeed. But to claim "GR has yet to find experimental refutation"
seems completely unjustified in the current situation with dark matter.

Ilja



"Dark Matter" is simply matter that is not emitting
or absorbing photons.... What has that to do with
General Relativity?

Sam - point taken - dark matter is matter that does no interact with photons
and does not violate the strong erg condition. Dark matter is not really
the same thing as dark energy but many (especially non technical accounts)
also use the term dark matter when referring to exotic states of matter that
violate the strong energy condition. That is what I mean by dark matter.
And violation of the strong energy condition is indeed very interesting to
GR. Its possible existence does not disprove it mind you - but it still is
rather interesting. Considering the furor my sense of the term has
generated I will stick to dark energy from now on.

Thanks
Bill


Scientists Map Dark Matter, Prove Einstein Right
http://www.space.com/news/cosmic_shear_000512.html

Particle Dark Matter: Evidence, Candidates and Constraints
http://arxiv.org/abs/hep-ph/0404175

Bill Hobba wrote:
"Sam Wormley" wrote in message
news:aPXSe.311421$_o.157432@attbi_s71...

Ilja Schmelzer wrote:


Indeed. But to claim "GR has yet to find experimental refutation"
seems completely unjustified in the current situation with dark matter.

Ilja



"Dark Matter" is simply matter that is not emitting
or absorbing photons.... What has that to do with
General Relativity?


Sam - point taken - dark matter is matter that does no interact with photons
and does not violate the strong erg condition. Dark matter is not really
the same thing as dark energy but many (especially non technical accounts)
also use the term dark matter when referring to exotic states of matter that
violate the strong energy condition. That is what I mean by dark matter.
And violation of the strong energy condition is indeed very interesting to
GR. Its possible existence does not disprove it mind you - but it still is
rather interesting. Considering the furor my sense of the term has
generated I will stick to dark energy from now on.

Thanks
Bill


Scientists Map Dark Matter, Prove Einstein Right
http://www.space.com/news/cosmic_shear_000512.html

Particle Dark Matter: Evidence, Candidates and Constraints
http://arxiv.org/abs/hep-ph/0404175




Thanks Bill--I have to do a bit of book'n here.

"Bill Hobba" schrieb
"Ilja Schmelzer" wrote
"Bill Hobba" schrieb
"mountain man" wrote
"Bill Hobba" wrote in message
Wrong. GR has yet to find experimental refutation.

Dont you mean GR plus the additional "dark matter"
postulate when considered together have yet to find
experimental refutation?

No. A simple cosmological model based on reasonable assumptions shows
the
acceleration should be slowing yet is observed to be accelerating.
This
either shows GR or some of the other assumptions that goes into the
model
is
false. The assumption that has been found wanting is not GR but that
matter
exists that may be 'exotic' by which is meant it violates the strong
energy
condition - one of the assumptions that goes into the model.

Why not GR?

No reason other than general consensus.

IOW no reason.

Please remember the logic of my
argument which is a model that consists of GR. plus the strong energy
condition plus some other assumptions has been experimentally refuted.
This
does not imply GR. is incorrect - the strong energy condition for example
may be at fault. Indeed this is the one that most articles I have read
look
at rather than GR. This of course does not prove GR. is not at fault -
but
it does not prove it is wrong either.

A typical situation in science. Single experiments falsify only combinations
of different theories. The GR Einstein equations, if taken alone (without
assumptions about matter) does not make any falsifiable predictions. Not an
argument against GR. But a strong argument that GR has problems if there is
strange dark matter.

In this case, we can never claim GR has been refuted. Because other
explanations can also explain every violation of the Einstein equations
G_mn = T_mn.


I disagree. If, for example, the precession of mercury was not as
predicted
or the Pound Rebka experiment was not as predicted GR. would be in serious
trouble.

Why? Why not save GR using T_mn^dark = G_mn - T_mn^obs?

If G_mn =/= T_mn we simply have to postulate dark matter as

T_mn^dark = G_mn - T_mn^obs

and the Einstein equation holds again.

Sure, but can every other test be explained away so easily? I doubt it.

I'm not talking here about experiment which falsify the EEP. (IOW I assume
that the true theory is another metric theory of gravity.)

In this case, obviously. The only question is if the dark matter term
T_mn^dark = G_mn - T_mn^obs has too strange properties.

But it follows from Bianchi identities and nabla T_mn^obs = 0 that
nabla T_mn^dark = 0. Thus, even energy and momentum conservation
holds.

Although the strong energy condition is looked upon as
suspect still other assumptions (not GR) could be at fault.

Indeed. But to claim "GR has yet to find experimental refutation"
seems completely unjustified in the current situation with dark matter.

I suspect this is a semantic issue. We have yet to find classical
phenomena
that refutes GR. By which I mean phenomena that forces us to abandon GR.
because no other reasonable explanation exists - we for example have
found
phenomena that refutes Newtonian gravity.

Only after a competitor (GR) was known and considered. As long as
alternative
theories are widely ignored no classical experiment will refute GR.

Please remember that it is even
not possible to prove the earth is not flat as discussions with flat
earthier will readily demonstrate with their conspiracy type arguments.
However most people would reject such and say we have proof it is not flat
because the other arguments simply do not make sense The same with GR. -
and I detailed above the type of experimental refutation I would accept
(and
I suspect most others would also accept) eg wrong precession measurements
on
mercury.

But why wrong precession of Mercury counts but wrong rotation of the Sun
around the center of the Galaxy not?

I think the question should be handled differently. We have to compare with
competing theories. If the competing theories are simple and reasonable
(small amounts of usual but dark matter somewhere) - fine. But if we need
97% "dark matter" which cannot be baryonic and violates even energy
conditions of usual baryonic matter the situation for GR is already very
bad.

Ilja

"Sam Wormley" schrieb
Ilja Schmelzer wrote:
Indeed. But to claim "GR has yet to find experimental refutation"
seems completely unjustified in the current situation with dark matter.

"Dark Matter" is simply matter that is not emitting
or absorbing photons....

and is non-baryonic and violates the strong energy condition and we have
30 times more of it than usual baryonic matter.

What has that to do with General Relativity?

I have already explained it.

Ilja

Ilja Schmelzer:
"Bill Hobba" schrieb

Dark matter is
supposed to do just that - violate the strong energy condition. Indeed if
inflation is correct the early universe violated the strong energy
condition. One can not claim GR has been refuted when other assumptions
can
also explain it.

In this case, we can never claim GR has been refuted. Because other
explanations can also explain every violation of the Einstein equations
G_mn = T_mn.

If G_mn =/= T_mn we simply have to postulate dark matter as

T_mn^dark = G_mn - T_mn^obs

and the Einstein equation holds again.

Sure, but you should know better than that. The fact that dark
matter is postulated because it _could_ solve a problem is quite
different from saying that dark matter solves a problem. The former
is reasonable hypothesis. The second is a misrepresentation of the
hypothesis for use as a strawman.

In real life, that sort of thing happens all the time in physics
(and every other scientific field). The resolution is to find out
_if_ dark matter does solve the problem by establishing the existence
or non-existence of dark matter independent of the phenomena dark matter
is supposed to explain. In some cases that is harder to do than in others,
but I think you'll dicover that historically, physicists have no
hesitation to abandon a ship they believe is going to sink in favor of
something more promising. The key words are ``more promising'' and
most physicists consider their own ideas most promising. That's
why people become physicists.

In any case, this thread bears little resemblence to reality. Even if
general relativity were pronounced dead tomorrow (as if there was some
official person in charge of doing that), I am quite certain that the
nonsense mountainman keeps posting would still never attract any interest.
It will still be nonsense regardless of whatever else happens. From a
realistic standpoint, if what he's peddling is the alternative, then dark
matter has already solved the problem. No one is going to abandon
something which could be correct in order to persue something that isnt
even coherent.

Although the strong energy condition is looked upon as
suspect still other assumptions (not GR) could be at fault.

Indeed. But to claim "GR has yet to find experimental refutation"
seems completely unjustified in the current situation with dark matter.

Why is that? Dark matter as a solution hinges on establishing its
existence independent of that for which it was proposed. Doing that is not
particularly simple. Your perspective is skewed by the un- precedented
advancements in science made during out lifetime. It took about thirty
years from the time maxwell proposed the addition of the displacement
current until the electromagnetic radiation it predicted was experimentally
verified. So long as no one verified the existence of the electromagnetic
radiation maxwell described independent of what it was assumed to
explain by design, you could say that maxwell's equations lacked any
experimental evidence for much longer than anyone has contemplated
dark matter.

Bilge: You have pointed out that the theory of dark matter has not been
proved, so the DMT does not disprove relativity. But I think you miss
the point. To the extent that observations require the postulation of
DM, then to that extent relativity itself is called into question. Why
can't you just be honest about the whole dispute, instead of being a
hired gun for the relativist position. You would appear to be more
scientific if you would give due regard to relativity questioning,
rather than start insulting people and playing the advocate with
religious fervor.

I know, I know; in your answer, if you bother to answer, you will spend
time insulting me. Why don't we just stipulate that your answer will be
presumed to contain 2,000 words of insults. This way we save a lot of
time, and you don't make yourself look so juvenile.

"Ilja Schmelzer" wrote in message
...

"Bill Hobba" schrieb
"Ilja Schmelzer" wrote
"Bill Hobba" schrieb
"mountain man" wrote
"Bill Hobba" wrote in message
Wrong. GR has yet to find experimental refutation.

Dont you mean GR plus the additional "dark matter"
postulate when considered together have yet to find
experimental refutation?

No. A simple cosmological model based on reasonable assumptions shows
the
acceleration should be slowing yet is observed to be accelerating.
This
either shows GR or some of the other assumptions that goes into the
model
is
false. The assumption that has been found wanting is not GR but that
matter
exists that may be 'exotic' by which is meant it violates the strong
energy
condition - one of the assumptions that goes into the model.

Why not GR?

No reason other than general consensus.

IOW no reason.

Fair enough.


Please remember the logic of my
argument which is a model that consists of GR. plus the strong energy
condition plus some other assumptions has been experimentally refuted.
This
does not imply GR. is incorrect - the strong energy condition for example
may be at fault. Indeed this is the one that most articles I have read
look
at rather than GR. This of course does not prove GR. is not at fault -
but
it does not prove it is wrong either.

A typical situation in science. Single experiments falsify only
combinations
of different theories. The GR Einstein equations, if taken alone (without
assumptions about matter) does not make any falsifiable predictions. Not
an
argument against GR. But a strong argument that GR has problems if there
is
strange dark matter.

I do not quite understand your reasoning here. The EFE's follow quite
readily from the fact that the Lagrangeian must result in the RHS being the
stress energy tensor and the LHS must be linear in the second differential
degree in the metric and hence linear in the Einstein curvature tensor. We
take the Newtonian limit and in suitable units G = T. A violation of the
strong energy condition would result in the appearance of a cosmological
term on the RHS not in a violation of any of the principles of GR ie the
Newtonian limit would not hold exactly.


In this case, we can never claim GR has been refuted. Because other
explanations can also explain every violation of the Einstein equations
G_mn = T_mn.


I disagree. If, for example, the precession of mercury was not as
predicted
or the Pound Rebka experiment was not as predicted GR. would be in
serious
trouble.

Why? Why not save GR using T_mn^dark = G_mn - T_mn^obs?

If G_mn =/= T_mn we simply have to postulate dark matter as

T_mn^dark = G_mn - T_mn^obs

and the Einstein equation holds again.

Sure, but can every other test be explained away so easily? I doubt it.

I'm not talking here about experiment which falsify the EEP. (IOW I
assume
that the true theory is another metric theory of gravity.)

In this case, obviously. The only question is if the dark matter term
T_mn^dark = G_mn - T_mn^obs has too strange properties.

But it follows from Bianchi identities and nabla T_mn^obs = 0 that
nabla T_mn^dark = 0. Thus, even energy and momentum conservation
holds.

Agreed.


Although the strong energy condition is looked upon as
suspect still other assumptions (not GR) could be at fault.

Indeed. But to claim "GR has yet to find experimental refutation"
seems completely unjustified in the current situation with dark matter.

I suspect this is a semantic issue. We have yet to find classical
phenomena
that refutes GR. By which I mean phenomena that forces us to abandon GR.
because no other reasonable explanation exists - we for example have
found
phenomena that refutes Newtonian gravity.

Only after a competitor (GR) was known and considered. As long as
alternative
theories are widely ignored no classical experiment will refute GR.

Are they being ignored? eg Uncle Als experiment.


Please remember that it is even
not possible to prove the earth is not flat as discussions with flat
earthier will readily demonstrate with their conspiracy type arguments.
However most people would reject such and say we have proof it is not
flat
because the other arguments simply do not make sense The same with GR. -
and I detailed above the type of experimental refutation I would accept
(and
I suspect most others would also accept) eg wrong precession measurements
on
mercury.

But why wrong precession of Mercury counts but wrong rotation of the Sun
around the center of the Galaxy not?


Yes I see your point.


I think the question should be handled differently. We have to compare
with
competing theories. If the competing theories are simple and reasonable
(small amounts of usual but dark matter somewhere) - fine. But if we need
97% "dark matter" which cannot be baryonic and violates even energy
conditions of usual baryonic matter the situation for GR is already very
bad.

That is where I do not necessarily agree - as noted above GR follows quire
reasonably even if the strong energy condition does not hold - the
cosmological term then is simply not zero. Although I suspect more complex
models that violate the strong energy condition, if proven true, may lead to
a revision of GR.

Thanks
Bill


Ilja