any comments on astro-ph/0509230

the title does look intriguing. at least the claims are very
extraordinary.
maybe the GR experts on this forum can shed light on whether any of
this
makes sense
Melroy

wrote:
the title does look intriguing. at least the claims are very
extraordinary.
maybe the GR experts on this forum can shed light on whether any of
this
makes sense
Melroy


I am no expert but...

WHERE would the universe rotate ????????

I mean the universe is everything. To rotate it would have to have
a limit, and an enclosing body where this "rotation" could be
measured. Then the universe would not be the universe but a part
of it, since it would be enclosed in a bigger body.

Q.E.D.

Rotation makes just NO SENSE when applied to the universe, excuse me.

But I am happy that it does not rotate, of course :-)

jacob

wrote:
whether any of this makes sense
Melroy

The "repulsive" force of gravity would have to be present and
observable in some area of the universe. Not mentioned in the paper.

Spud

In article om,
writes:

the title does look intriguing. at least the claims are very
extraordinary.
maybe the GR experts on this forum can shed light on whether any of
this

I haven't yet read the paper. Here are some comments on the abstract:

The negative pressure associated with
a large vacuum energy prevents an event horizon from forming, thus
resolving the long-standing puzzle as to why gravitational collapse
always leads to an explosion.

Is this really a puzzle? First, the statement is illogical, for if
sometimes collapse did NOT lead to an explosion, then such cases would
probably not be noticed observationally. Second, with a supernova or
whatever the idea is that some of the energy generated by the collapse
powers an explosion whereas the stuff not carried away by the explosion
continues to collapse. Where is the puzzle here?

(If the authors are referring to THEORETICAL arguments, rather than
OBSERVATIONAL ones, as to collapse always resulting in an explosion,
then if the arguments are convincing then the theory must be well
understood, thus there can be no puzzle. If they are not convincing,
then the statement is wrong, and again there is no puzzle.)

An indirect consequence is that the
reverse process - creation of matter from vacuum energy - should also be
possible. Indeed this process may be responsible for the "big bang". In
this new cosmology the observable universe began as a fluctuation in an
overall steady state universe.

Forget vacuum energy, forget the steady-state universe. ANY universe
can form as a fluctuation in another universe. Unlikely? Perhaps.
However, as Penrose has pointed out many times, the standard big bang
has such a low entropy that it is more likely that the entire observed
universe arose fully formed via a fluctuation than that it evolved from
such a low-entropy big bang, at least if standard physics is all that is
involved. (Penrose does believe in the big bang, but invokes the Weyl
curvature hypothesis to explain the low entropy.) Regardless of what
one thinks of Penrose's other ideas, I've never seen a good rebuttal to
this argument; the puzzle of the low-entropy big bang seems to be
glossed over by most people.

From the paper on dark energy stars cited (which is also by one of the
authors):

Event horizons and closed time-like curves cannot exist in the real
world for the simple reason that they are inconsistent with quantum
mechanics.

There is an assumption here. Admittedly a common one, but an
assumption. Everyone knows that QM and GR conflict. The assumption is
that QM is absolutely true and that GR must be modified. Why not the
reverse? (Again, Penrose has championed this view, and provided at
least some plausibility arguments for it.)

In message , jacob navia
writes
wrote:
the title does look intriguing. at least the claims are very
extraordinary.
maybe the GR experts on this forum can shed light on whether any of
this makes sense
Melroy


I am no expert but...

WHERE would the universe rotate ????????

I mean the universe is everything. To rotate it would have to have
a limit, and an enclosing body where this "rotation" could be
measured. Then the universe would not be the universe but a part
of it, since it would be enclosed in a bigger body.

Q.E.D.

Rotation makes just NO SENSE when applied to the universe, excuse me.

But I am happy that it does not rotate, of course :-)

There's no problem with the idea of the universe rotating, and according
to George Smoot in "Wrinkles in Time" you don't have to ask "relative to
what ?" (no, I don't understand that. I'm no expert either :-)
Godel found that a rotating universe allows time travel.
And while COBE found evidence that the universe doesn't rotate, didn't
someone look at asymmetries in galactic magnetic fields and claimed that
it does, or at least a very large part of the observable universe does?
--
Boycott Yahoo!
Mail to jsilverlight AT merseia DOT fsnet DOT co DOT co DOT uk is welcome.

In sci.astro.research wrote:
[[about Chapline's astro-ph/0509230]]
the title does look intriguing. at least the claims are very
extraordinary.
maybe the GR experts on this forum can shed light on whether any of
this
makes sense

I would describe Chapline's work as "highly speculative", to say the
least.

Lubos Motol has written a strong critique of Chapline's work at
http://motls.blogspot.com/2005/03/ch...ont-exist.html
Apart from the many technical points where Chapline is way out on
some pretty thin ice, I found it remarkable that Chapline claims that
negative heat capacity is impossible. (It's actually ubiquituous in
large-N Newtonian N-body self-gravitating systems, eg globular clusters
and suchlike.)

This passage (of Motol's, reporting on a Chapline seminar at MIT)
# Someone asked whether Chapline's new picture of the black hole also
# requires one to alter the membrane paradigm by Kip Thorne, in which the
# horizon is viewed as a superconducting membrane, and the answer was that
# the speaker did not know what the paradigm was.
suggests that Chapline is seriusly uninformed about GR -- Thorne's
"membrane paradigm" is a _very_ standard concept in GR, and there's
a well-known textbook on it by Thorn, Price, and MacDonald, which
I'd expect any serious researcher to at least be aware of.

ciao,

--
-- "Jonathan Thornburg -- remove -animal to reply"
Max-Planck-Institut fuer Gravitationsphysik (Albert-Einstein-Institut),
Golm, Germany, "Old Europe" http://www.aei.mpg.de/~jthorn/home.html
"Washing one's hands of the conflict between the powerful and the
powerless means to side with the powerful, not to be neutral."
-- quote by Freire / poster by Oxfam

Jonathan Silverlight wrote:
There's no problem with the idea of the universe rotating, and according
to George Smoot in "Wrinkles in Time" you don't have to ask "relative to
what ?" (no, I don't understand that. I'm no expert either :-)
Godel found that a rotating universe allows time travel.
And while COBE found evidence that the universe doesn't rotate, didn't
someone look at asymmetries in galactic magnetic fields and claimed that
it does, or at least a very large part of the observable universe does?

There are other conceptual problems.
Rotation implies a center where the rotation is zero. The Universe
would have to have a center, what would make some point in the
universe VERY special and easy to spot... Everything in a rotating
body points to its center of rotation. It is a point that is easy to
spot.

What the book of Smoot is concerned ("Wrinkles in Time") I found only
one sentence (p 182) about this:

"Also, the absence of rotation of the universe, which we noted during
our U2 observations, becomes less of a puzzle in an inflationary
universe". Strangely, in the chapter about the U2 observations he
writes about a lot of things (The U2 pilots, Lima in Peru, etc etc) but
I did not find anything about the rotation of the universe.






There is also the
talk of Mrs Rubin, that held a conference in december
1950 about "The rotation of the universe". I cite Smoot again (page 143)

"Her talk had originally been titled "Rotation of the Universe" but the
meeting organizer thought that sounded odd, and so he had changed it to
"Rotation of the Metagalaxy". "

I would share the feeling of the meeting organizer. A "rotating"
universe is completely ridiculous. And note that there is a HUGE
difference between a "rotating universe" and a "very large part of
the observable universe". I am ready to accept the second if there is
data supporting that. But the first is just NONSENSE, and I am sure
there will be never any data to support it!

Nowhere however, I find any mention of this elementary questions in the
book of Smoot. He just writes that he doesn't have any data about the
rotation without discussing in detail how could he even consider such
an absurdity.

jacob

In article ,
jacob navia wrote:

There are other conceptual problems.
Rotation implies a center where the rotation is zero.

This is intuitively obvious, so it should come as no surprise that
it's not true.

In general relativity, there are solutions to the Einstein field
equation that describe a Universe that is rotating but that has
no center. Specifically, there are homogeneous (but not
isotropic) cosmological models in which every point can
equally well be regarded as the center of rotation.

Remember when you first learned about the expansion of the Universe?
Back then, it probably seemed completely obvious that you couldn't
have expansion without having a center away from which everything was
expanding. After a while, you probably learned enough to get used to
the idea of expansion without a center. Most people just haven't
spent enough time thinking about rotating cosmological models to get
used to the idea of rotation without a center.

As others have pointed out, we don't seem to live in such a Universe:
observations give a very strict upper limit on the rotation rate. But
such a Universe is theoretically possible, so it's a valid and
interesting question to ask why we don't live in one.

-Ted

--
[E-mail me at , as opposed to .]

In message , jacob navia
writes
Jonathan Silverlight wrote:
There's no problem with the idea of the universe rotating, and according
to George Smoot in "Wrinkles in Time" you don't have to ask "relative to
what ?" (no, I don't understand that. I'm no expert either :-)
Godel found that a rotating universe allows time travel.
And while COBE found evidence that the universe doesn't rotate, didn't
someone look at asymmetries in galactic magnetic fields and claimed that
it does, or at least a very large part of the observable universe does?

There are other conceptual problems.
Rotation implies a center where the rotation is zero. The Universe
would have to have a center, what would make some point in the
universe VERY special and easy to spot... Everything in a rotating
body points to its center of rotation. It is a point that is easy to
spot.

What the book of Smoot is concerned ("Wrinkles in Time") I found only
one sentence (p 182) about this:

"Also, the absence of rotation of the universe, which we noted during
our U2 observations, becomes less of a puzzle in an inflationary
universe". Strangely, in the chapter about the U2 observations he
writes about a lot of things (The U2 pilots, Lima in Peru, etc etc) but
I did not find anything about the rotation of the universe.






There is also the
talk of Mrs Rubin, that held a conference in december
1950 about "The rotation of the universe". I cite Smoot again (page 143)

"Her talk had originally been titled "Rotation of the Universe" but the
meeting organizer thought that sounded odd, and so he had changed it to
"Rotation of the Metagalaxy". "

I would share the feeling of the meeting organizer. A "rotating"
universe is completely ridiculous. And note that there is a HUGE
difference between a "rotating universe" and a "very large part of
the observable universe". I am ready to accept the second if there is
data supporting that. But the first is just NONSENSE, and I am sure
there will be never any data to support it!

Nowhere however, I find any mention of this elementary questions in the
book of Smoot. He just writes that he doesn't have any data about the
rotation without discussing in detail how could he even consider such
an absurdity.

Au contraire :-)

Looking at my copy (ISBN 0316905089) there are two entries in the index,
pages 115 and 135. Page 115 is just about Kurt Godel's idea, but 135
says
"it began to be all too clear to us that the DMR data contained no hint
of rotation of the universe. This was a major surprise, because we can
see that everything within the universe is rotating - planets, stars,
and galaxies. I had convinced myself that the universe should be
rotating.... I knew that general relativity allowed rotation in spite of
the inevitable question: what does the universe rotate with respect to?
From our results, we calculated that if the universe does rotate, it
does so at lass than on hundred-millionth of a rotation in the last
billion years".

It's the most accessible account of this idea I found.

Also, I found a web page about the asymmetry
http://www.rochester.edu/pr/releases/phys/borge.htm, which was linked
from Daniel Fischer's Cosmic Mirror page
http://www.astro.uni-bonn.de/~dfischer/mirror41-50.html (Item
"Physicists baffled: Is the Universe anisotropic?") Rereading it, I see
they aren't saying that the universe is rotating but that it has a
preferred orientation, which is probably just as heretical :-)

In article ,
wrote:
In general relativity, there are solutions to the Einstein field
equation that describe a Universe that is rotating but that has
no center. Specifically, there are homogeneous (but not
isotropic) cosmological models in which every point can
equally well be regarded as the center of rotation.

Remember when you first learned about the expansion of the Universe?
Back then, it probably seemed completely obvious that you couldn't
have expansion without having a center away from which everything was
expanding.

And in fact, just as there's a simple Newtonian/Euclidean proof that
there is no centre in a universe that obeys Hubble's law, even though
it appears that everything is receding from us, there's a simple proof
in vector algebra (exercise for the reader) that there is no centre in
a universe where it appears that all bodies are moving around us with
constant angular speed. Thus this isn't, particularly, some
peculiarity of general relativity.

Martin
--
Martin Hardcastle
School of Physics, Astronomy and Mathematics, University of Hertfordshire, UK
Please replace the xxx.xxx.xxx in the header with star.herts.ac.uk to mail me