Re: Why strings are required to halt collapse (was: black holes and singularities)

From: MP (pet.antispam_at_onlinehome.de)
Date: 12/08/04 

Date: Wed, 8 Dec 2004 18:08:05 +0100

"Ilja Schmelzer" <q6867901@mailstore.fernuni-hagen.de> wrote in message
news:cp6bi9$o7d$1@beech.fernuni-hagen.de...
>
> "MP" <pet.antispam@onlinehome.de> schrieb
> > "Randy M. Dumse" <rmd@newmicros.com> wrote
> > > "MP" <pet.antispam@onlinehome.de> wrote
> > > > Yet I don't really think that a matter-distribution confined to a
thin
> > > > spherical shell can be stable
> > >
> > > I agree. Which is why I resist the idea of matter confined to a thin
> > > spherical shell, and think only of a radiation shell. (We don't need
to
> > > reexamine if radiation should be called matter. You will always find I
> > > side with the idea it radiation is excluded from discussions of
matter.
> > > I make that distinction so as not to forget the unique properties of
> > > radiation, and to remain open to more yet to be found.)
>
> I don't know the details, but AFAIK the energy conditions which are
> necessary to predict the collapse are fulfilled by radiation too.

They are. For radiation (in the sourceless region)

\rho + P1 + P2 + P3 = 2 \rho

(because trace of the stress-energy tensor is zero)

so the strong energy condition is always fulfilled (no matter
what direction radiation takes) unless the energy-density
of radiation were negative.

> > I have been very skeptical of string theory, too. Have been much
> > more in favor of the loop guys and girls. Until I realized that the
> > singularity free solution for a compact object, that I found when
> > I was analyzing a particularly interesting class of spherically
> > symmetric metrics, actually is nothing else than a solution with
> > string type interior matter.
>
> I wonder why you think such a solution is important.

Because I studied its properties. And found them to be
not only very interesting from a theoretical point of view,
put to be concordant with many features you find in the
observable universe today. [Not everything is concordant,
though. At least there are several open problems, some
of which I see a possible solution, some I don't.]

Of course this concordance could be chance.
However, the more concordance you find, the less likely
chance becomes. Another possibility could be, that there
are some mistakes in the analysis. Here I can only say,
that I have been very careful, to best of my abilities. The
crucial question here is, how good these abilities are. That
is not for me to judge, fortunately.

Of course I am aware, that my belief is not universally
shared. There is no problem with this. I am not a missionary
for the *importance* of a certain solution, or certain results.
It is the sole responsibility of any serious researcher to decide
for himself, what research of others he finds important and
what not. My responsibility is to decide what I find important,
to do the analysis in the most objective way possible, and to
present the results in such a way, that the assumptions and
calculations can be checked by my fellow researchers.

> Ok, may be such a stringy solution is of some interest near the
> BH singularity. But near the surface? According to GR ideology
> we have quite normal conditions near the surface of large BHs.
> Thus, some fundamental stringy nature of matter will remain
> unimportant. Not?

Well, if you think the physically realized solutions of the Einstein
field equations for a large compact self-gravitating object are the
black hole solutions you are certainly correct. There is vacuum
at the event horizon of a black hole. [I guess I pointed this out
several times in this NG] As there is vacuum and the curvature
is negligible for a large black hole at the event horizon, there
cannot be any strings there, either.

But my point is that I believe, based on the analysis of the
solution I found, that a large compact self-gravitating object
is not correctly described, in *classical* GR, by the black
hole solutions, but by a different solution of *classical* GR,
along the lines of the "holographic solution" [or the solution
desribed by Samir Mathur]. The problem in GR is, that the
mathematical solution space is vastly larger than the physical
solution space. There is no a priori method to extract the
physical solutions from the vast mathematical solution space.
The only way is to study a solution and compare your results
to observations or theoretical expectations from other fields.
This is what I have done.

Of course you can always say, that the holographic
solution (or Mathurs solution) gives a very different picture of
the interior space-time of a large compact self gravitating
object than the universally accepted black hole solutions and
thus must be wrong. It is hard to argue against this.

[I guess you have experienced something similar with GET. ;-)
BTW, I think you did a very good job, and it is somewhat
sad that such a job is not much recognized, at least not by
the mainstream.]

> > So now, because you asked, I will make some moderate
> > advertisement for the holographic solution.
> >
> > As I already pointed out, the holographic solution is the simplest
> > solution of the field equations, and its properties are very much
> > concordant with the properties of the observable universe.
>
> I do not see such a concordance.

Of course you don't. You would have to study the solution.
Or you would have to read the papers written about this
solution and believe them to be correct. Now, I wouldn't
believe a non peer reviewed paper from an unknown
source, unless I have checked the results myself. So I
guess, you have to either check the results yourself or
wait until a peer-reviewed paper appears. [in this case
the referees would have done the checking for you :-)]

> > [Of course MP has some very strange, heretical views
> > about how classical GR must be understood: MP is of the
> > opinion, that nobody has properly understood *classical*
> > GR, who has not (yet) grasped the beauty of classical GR
> > expressed in a string context. Vice versa MP holds the
> > widely unsupported belief, that nobody has properly
> > understood string theory, if she has not (yet) understood
> > that *classical* GR requires strings in order to produce
> > sensible results, not only in high, but even more so in
> > *low* energy situations. End of digression :-)]
>
> This is exactly what I don't understand. Why do we need
> string theory for our low energy observations (which include
> the neighbourhood of large BHs)? Note that if we have to
> modify our low energy equations, all the low energy observational
> support for GR disappears.

Well, first of all you shoudn't take any "digression" of MP
too seriously. I have specifically marked the paragraph
you referred to as "digression", because it does not contain
anything that can be checked. So it is not scientific. It
shows MPs views and beliefs. They are irrelevant, at
least they should be to you. :-)

Relevant is what can be checked, because a calculation
has been done, or some at least plausible arguments have
been invoked!

But in order to answer your question:

We don't have to modify the low energy equations at all.
I am not proposing *any* modification to GR [at least
not at the low energy regime]. But I am proposing that
the correct EOS for matter on sufficiently large scales
is a string equation of state.

Why? This cannot be answered in just a few lines.
Look into the papers or study the metric

r0/r dt^2 - r/r0 dr^2 - r^2 d \Omega

yourself. [But only if you are interested, not to do
me a favor. It is *your* time, which you might invest
wisely - or maybe not so wisely, if you follow my
advice :-)]

Best MP

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