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

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

Date: Sun, 12 Dec 2004 12:34:46 +0100

"Bilge" <dubious@radioactivex.lebesque-al.net> wrote in message
news:slrncrmscr.43f.dubious@radioactivex.lebesque-al.net...
> MP:
>
> >I guess the problem with most researchers is, that they don't
> >wan't to do the thinking theirselves [unless it is along the
> >very slim topic in which they are experts].
>
> That simply isn't the case. One becomes an ``expert'' on a topic
> by recognizing why that topic has more general relevance.

Agreed. Maybe I should not have used the word "most". [The
use of the world was based on my personal experience in the
field where I am expert: spherically symmetric string type solu-
tions in GR]

But in becoming an "expert" it is solely your own responsibility
to recognize the topics of relevance. This responsibility cannot
be delegated to others.

[...]

> While you might primarily be interested in gravity, a great deal of
> data relevant to astrophysics comes from rather specialized topics that
> ends up having a great deal to do with interpreting cosmological data.

But the interpretation of the data depends crucially on the model
you choose. GR requires us to pick the *correct* model first:
There is no absolute space and time, [and most likely no ether,
sorry Ilja, but I still like your theory from a purely theoretical
point of view] which would enable us to say 'a priori' which
metric or which model to choose.

The FRW-model is based on the assumption, that the universe
is isotropic [and homogeneous] on large scales *everywhere*.
It (so far) has been an excellent description of the observable
phenomena in the universe. But isotropy at every point, back
to the "instant" of the big bang, is not a physical law, it is a
reasonable assumption. [of course inflation can, in some sense,
do away with perfect homogeneity of the initial state; but then,
inflation is a reasonable assumption, too. In fact, an assumption
necessary for the FRW-model, because otherwise the
theoretical and conceptual problems of the FRW-model
are very difficult to overcome]

There is nothing to be said against these assumptions. In fact,
I have said that reasonable assumption are necessary to make
progress. But if there is a different model, that explains all [or
most] of todays observations, but is not built from the same
assumption as the FRW-model, then it would not be a good
scientific argument to say, that the new model cannot be right,
because it doesn't have the same set of assumptions as the
[very successful] FRW-model. Rather such an argument
degrades the status of the former "reasonable assumptions"
of the FRW model to the status of "prejudice", because in
such a case the prime motivation to accept a model would not
be that it explains the *observations*, but rather that it is con-
cordant with the assumptions of the first [and not the second]
model, that researchers were able to come up with to explain
the observations.

And the insistance in homogeneity and isotropy as physical
law would even more become a prejudice, if the new model
*predicts* these features [without having to assume them]
in an unambigous way that is fully consistent with observations.

Of course requesting that a new model (that is not yet able to
explain everything the standard model can) shall prematurely
be elevated to be the new standard is no better prejudice than
the first. This is why I have said, that it is too early to say
that the FRW model or inflation has been debunked.

But if the new model has some advantages over the old, if
it makes predictions that the old model cannot, and these
predictions are concordant with observations, it would be
silly not to analyse the properties of the new model, just
because people who have become to love the old model
tell you, your model cannot be right for various vague
reasons. It is not the vague opinions of researchers, not
even of the majority of researchers, who are to decide
what scientific theory or model is best suited to describe
the real physical world in which we live. The ultimate
judge in these matters is the outcome of the tedious
comparison of a model's predictions with observations,
which might eventually falsify one or the other model.

> researchers didn't do ``the thinking theirselves [sic]'' as to how their
> research was relevant to physics in general, you would see nuclear phys-
> icists, for example, just cataloging reactions, rather than concentrating
> on nuclear reactions which have an impact that is much broader in scope
> than supporting a cottage industry for the nuclear shell model.

I guess there is a different view of what you mean by "thinking
yourself" and what I mean. I mean by "thinking yourself" that you
think a problem through from beginning to end, that you have done
all the necessary calculations yourself, that you have checked your-
self what explicit and implicit assumptions you have built your calcu-
lations on, and how reasonable these assumptions are, e.g. in
what situations they might fail. This is what I mean by "thinking your-
self." Of course someone who is expert in nuclear physics would
not have the time to make such an investment in a different field,
say GR. But if you are doing GR seriously, which has to a large
part become a theory of event horizons, singularities and trapped
surfaces, you have to understand why this is so, at a deep funda-
mental level. And for this you would have to know the singularity
theorems and their assumptions in and out. You would have to
know, in which situations the assumptions apply, in which not,
and you would have to think very hard about their reasonable-
ness. If you don't to that, e.g. if you can only parrot the majority
opinion in a vague way, then you lack the necessary qualification
to judge the works of others in this particular field.

> >They hold on to their prejudices as long as they can, often not even
> >being able to see that they are prejudices. Now I am not arguing about
> >prejudices. They are a good, because without any prejudices [or call
> >them by their other name: "reasonable assumptions], you will never be
> >able to make progress.
>
> Physicists hold on to what you call ``predjudices'', when abandoning
> them to solve a very narrow pet problem simultaneously ``unsolves''
countless
> other problems that have already been solved in a way that agrees with
> experimental data. Lots of crackpots on this newsgroup want to find a way
> to ``explain'' relativity and similarly use the argument that physicists
> are biased when offering their so-called ``theories'' as ``original
> thinking.''

"Original thinking", ususally without any calculation, usually even
lacking the broad framework in which a calculation, or a
prediction, at least could be done. Some "bogus" calculations,
where you can see from the onset that they are based on
fundamental misconceptions, long thought to be overcome, ...

Yes, I don't even look at such posts. But this sort of "original
thinking" was not the original topic of this post. The original
topic was how strings can halt collapse. I have given some very
specific arguments, fully within the context of classical GR.
However, the specific arguments put forth obviously were
not of much interest. The topic of the discussion rather has
turned into a meta-discussion, loosing its original focus and
wheeling off into realms, where rather opinions than arguments
are exchanged [Not that I see, that I have been at least
partly responsible for this loss of focus]

> Unfortunately, the mistake their lack of a broad understanding
> of physics for original thinking and typically don't even understand why
> the ``problem'' they've solved (which was only a problem in that the
> ``establisment'' solution offended their naive idea of common sense),
> has any connection to other physics. I'm not going to accept a theory
> which in the mind of some crackpot ``solves'' some personal issue they
> have with time time dilation if their solution doesn't also explain
> everything else that follows from relativity (like charge conservation
> from lorentz and gauge invariance, etc.)

I wouldn't either.

> >But sometimes, in order to make progress, especially in a situation
where
> >progress has stalled for decades, you might have to reevaluate your
> >prejudices. And in order to do that, you have to be able to see them as
> >they are: assumptions, but not physical law.
>
> Exactly what has been ``stalled for decades'' due to assumptions?

Where are the states of a black hole? What happens at space-
time singularities [assuming they exist]? How is the matter-side
of gravity constructed from first principles? Etc. ...

And why is it, that [almost] everyone believes that singularities
*must* exist in the real physical world? What assumptions
would lead to such a belief?

> What assumptions do physicists see as being physical law?

Some researchers obviously think that all of the assumptions
of the singularity theorems are undisputable physical law.
[although these assumptions often are not even known. How
else should one understand an argument of the kind: "Your
solution must be wrong, because I guess it violates one of the
assumptions of the singularity theorems, I don't know which."]

Other researchers obviously think, that the observable universe
*must* be describable by an FRW-model, which would elevate
the cosmological principle [which is merely a reasonable
assumption, that can always be falsified] to the status of
indisputable physical law.

How often have I read the categorical statement, the universe
has no center. Yes, this is true, *if* the FRW-model is the
correct model. But it is *not* true, if the FRW-model is just
an approximation [such as in the holostar model].

Now I wouldn't mind if we'd tell someone who asks this
question, that we have good evidence for our belief, that
the universe has no center, because this is a prediction of
the FRW-model - and the FRW-model describes the
universe very well. But I seldom see such a carefully phrased
answer. I rather see very authorative answers that leave
no room for doubt.

> About the assumption
> that seems to have that status is that different observers shouldn't
> require different physical laws (whatever those might be) to describe the
> same universe. Conservation of charge is about as high up on the list of
> assumptions as it gets and I can't imagine that physicists wouldn't
> abandon that assumption if doing so were of some advantage. I can see
> refusing to abandon it if doing so only solved some pet problem while
> ``unsolving'' all of the problems solved by the standard model.

So far I don't see any advantages in abandoning charge
conversation or the POE. I am not arguing to abandon all
reasonable assumptions with no benefit at all. There must
be at least the potential for a benefit. And a new assumption
[or theory] replacing an old assumption [or theory] must at
least have the *potential* to explain everything the old
theory can, and then somewhat more. And when it is first
proposed it should explain at least the basic predictions
of the old model and it should explain why there might be
enough potential to explain the other predictions, and more.

> If one wishes to offer an alternative to a theory, the amount of
> effort required depends upon the point at which they wish to depart
> from conventional physics. Offering an alternative to qed would be
> hard. Offering an alternative to relativity means offering an alternative
> to the entire standard model, since an altenative to relativity that
> can't explain what relativity explains, is not an alternative. The
> standard model can be derived from a only a few assumptions, none of
> which would seem to be especially controversial. The assumptions
> that go into general relativity are even fewer.

Correct. But I don't see the relevance of your statements to the
topic of this thread. The original topic was not an alternative
to qed, nor to conventional physics, to relativity or to GR. We
were discussing how IN THE CONTEXT OF GR gravitational
collapse can be prevented by string matter. I discussed this
within the context of an EXACT SOLUTION OF THE FIELD
EQUATIONS OF GR, a solution which obeys all of the energy
conditions, which has no timelike loops, and which has no
singularities. None of these assumptions would appear
especially controversial. And then, anybody who knows
GR can study its properties, and compare the results to
the observations or the theoretical expectations of other fields.

I guess, this makes the holographic solutions somewhat
different from crackpot-theories. Don't you think?

> >Researchers, instead of doing research (i.e. finding out something new),
> >rather requesting what I call "safe passage through the wilderness": a
> >referee, an authority, a text-book, or the majority opinion, which can
> >safely be parroted.
>
> The journals are full of speculation. I can just look through the
> ``new'' submissions to arxiv.org and find lots of speculation.

Of course. The B-brothers even managed to get their unintelligible
article into a prestigious journal. Now this journal is even more
risk-averse.

> Would you prefer the physics journals to be full of articles which don't
> meet some standard that makes them reliable as a basis for research?

Not at all. My point does not lie with the journals. You might have
seen that I argued quite in favor of the journals and of peer-review.

But neither is it true that everything in the journals is correct [see
for instance the Immirzi-parameter calculations of LQG, or the
B-brothers], nor is it true that everything that doesn't make it into
the journals is incorrect or certainly irrelevent [see for instance
Ilja's GLET theory, or Garth Barbers SCC, which even makes
some very interesting testable predictions].

So although you can much more safely "parrot" all that has been
published in a journal ["parroting" means: believing the results
without having checked the calculations and assumptions
thoroughly by yourself], it still is your sole responsibility to
decide what you believe without checking, what you believe
after checking and what you don't believe at all and don't
even care to check.

However, true understanding can only be gained by checking and
calculating results yourself, but not by parroting, no matter
how reliable the source from which you parrot might be.

> Someone who is doing research
> in general relativity ought to be able to rely on the articles published
> by other physicists without having to become experts in experimental
> nuclear astrophysics to decide that models of stellar evolution have
> some minimum level of reliability so that they can do general relativity
> with the interpreted data.

Sure. But somebody who does research in GR about compact
objects [and the universe is such a compact object, as its matter-
density is close to critical], should be able to assess for himself,
*not* relying on the assessment of others, whether e.g. the assumptions
of the singularity theorems are reasonable, particularly in light of
the new cosmological observations, why they are reasonable,
and he should be able to realize that in particular the trapped
surfaces are not at all a self-evident assumption. [See eg.
Weinberg, Gravitation and cosmology]

Best MP

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