Re: How can I become an expert anti-relativist?

From: Bill Hobba (bhobba_at_rubbish.net.au)
Date: 11/01/04 

Date: Mon, 01 Nov 2004 04:10:26 GMT

"Bill Hobba" <bhobba@rubbish.net.au> wrote in message
news:5oCgd.3343$K7.2912@news-server.bigpond.net.au...
>
> "MP" <pet.antispam@onlinehome.de> wrote in message
> news:cltt9f$7fp$1@online.de...
> >
> > "Bilge" <dubious@radioactivex.lebesque-al.net> wrote in message
> > news:slrnco4iri.93p.dubious@radioactivex.lebesque-al.net...
> > > MP:
> >
> > ...[snip]
> >
> > > >However, the singularity theorems, as any true mathematical theorem,
> are
> > > >based on assumptions.
> > >
> > > I think you've misrepresented things a bit, given that there exist
> > > zillions of papers that examine those assumptions. You fail to dif-
> > > ferentiate between knowing enough to recognize an ignorance of the
> > > most fundamental principles and knowing enough to be an expert at
> > > something that isn't relevant to addressing someone's ignorance of the
> > > fundamentals.
> >
> > That wasn't my point.
> >
> > > Requiring someone to understand singularity theorems
> > > in general relativity as a prerequiste to being competent enough to
> > > tell someone that relativity is a theory of spacetime geometry is
> > > nonsense.
> >
> > Agreed. That wasn't my point, either
> >
> > > Here's a question for you along the same lines. Do you assume
energy,
> > > momentum and angular momentum are conserved (and by that, I mean if
you
> > > include the energy dissipated by frictional forces, viscous damping,
> > > etc.)? If so, why? Can you prove those conservation laws
mathematically?
> >
> > Do you propose a proof in the context of GR or some other context?
Without
> > stating one's basic assumptions a proof is meaningless. You can never
> prove
> > your basic assumptions. You can check, if the assumptions are internally
> > consistent. You can check, whether the results derived from the
> assumptions
> > agree with experiments, observations.
> >
> > > Do you know what assumptions are necessary to prove them? Do you think
> > > it's necessary to know how to prove those conservation laws before one
> has
> > > enough knowledge of physics to recognize when someone else doesn't
> under-
> > > stand the basic principles of relativity (or even newtonian
mechanics)?
> > >
> > >
> > > > Now I suggest an experient: Ask a relativist,
who
> > > >claims you haven't understood relativity, whether he/she believes in
> > > >singularities. The common answer will be: Certainly, why ask?
(ignore
> > the
> > >
> > > Mr. kennaugh's misunderstanding of relativity is at the level of
> > > understanding the basic concept of geometry in _special_ relativity.
> > > It requires no knowledge of singularity theorems, nor does someone
> > > even need to have an in depth understanding of special relativity to
> > > point out that someone else doesn't understand the most basic
concepts.
> >
> > It was not my point, to defend Mr. Kennaugh's misunderstandings. There
is
> no
> > doubt that someone with a medium level of understanding can spot,
whether
> a
> > person has an even lower level of understanding. However, especially in
GR
> > (not so much in special relativy) one has to be careful to distinguish
> > between the "true understanding", that one has gained because one has
> > thought a problem through from all sorts of angles (and possibly made
> > several mistakes until realizing the truth) and the "shallow level" of
> > understanding, which consists of merely repeating that what others have
> > proved or said. In order to point this out, I have taken the singularity
> > theorems as one particular example. Neither does this mean, that I
think,
> > only who understands the singularity theorems has truly understood GR,
nor
> > does this mean, that I think, I have a particularly good understanding
of
> > these theorems.
> >
> > In fact, I have a medium level of understanding. I know the assumptions,
> on
> > which the proof is based (this is absolute essential knowledge, and
> > therefore nothing to brag about!). I know the sketch of the proof. But I
> > have not proved them myself in full and therefore I don't pretend to
> > understand all intricacies of the proof. But I have no doubt, that the
> > people who actually developed the singularity theorems and the people
who
> > have improved them, have an excellent understanding of these matters.
But
> > somebody who has not even looked at the assumptions should not pretend,
> that
> > he has understood this aspect of GR. Unfortunately this happens all to
> > often. And this, and only this, was my complaint and my point.
> >
> > > >undertone of slight superiosity). Then ask, on what assumptions this
> > belief
> > > >is based. The common answer will be: The singularity theorems, you
> don't
> > > >know?!. Again ignore the growing undertone of superiosity. Now comes
> the
> > fun
> > > >part: Ask on what assumptions the singularity theorems are based.
This
> > is
> > > >where the common wisdom of the crowd usually fails, and the emperor
> > finally
> > > >stands naked. Most likely you will not get a decent answer.
> > >
> > > So, should I assume that would deem einstein unqualified to
determine
> > > whether or not someone understands even the most basic concepts of
> > > relativity because (1) he obviously knew nothing about singularity
> > > theorems, since he died before any existed, and (2) had an opinion
> > > about singularities anyway?
> >
> > That was not my point. Einstein was highly unqualified. Knowing about
the
> > singularity theorems is just one small aspect of the mathematical
> structure
> > of GR. In my opinion not even of too much physical relevance.
> >
> > ...[snip]
> >
> > > >What use is a mathematically
> > > >correct theorem, if one of its crucial assumptions is badly violated
> in
> > the
> > > >true physical world? Sadly, most relativists cannot (or will not)
draw
> > the
> > > >obvious conclusion.
> > >
> > > Well, let's apply that argument to maxwell's equations. There is
> > > absolutely no question whatsoever that maxwell's assumptions are badly
> > > violated by the true physical world in blatantly obvious ways. That
> > > isn't even controversial, given the fact that charges are discrete
> > > and light comes in discrete quanta. Apparently maxwell himself would
> > > be incompetent by your criteria since he certainly had no idea that
> > > his equations hinged on the photon being massless.
> >
> > I wasn't arguing against GR, nor was I arguing against Einstein or
> Maxwell.
> > In fact, I believe that GR describes the world very very very well. But
I
> am
> > arguing against *applying* GR in a wrong and inconsistent way. For
> instance,
> > it is incorrect to say, given the experimental evidence we have today
> > (accelerating universe), that it has been *proven* that singularities
must
> > exist or must necessarily form in the real physical world (assuming the
> > world is truly described by GR). If the apparently measured acceleration
> of
> > the universe is real, the strong energy condition is violated,
>
> It is not - the equation you pointed to that supposedly showed the strong
> energy condition was violated (Wald - equation 5.2.13) was devolved using
> the assumption of a zero cosmological constant. What it shows it that if
> the strong energy condition holds then, if the cosmological constant is
> zero, the rate of expansion must be slowing. But we now think it might be
> increasing- not slowing - all this shows is that we may have a non zero
> cosmological constant - not that the strong energy condition is violated.

I just wanted to add in light of my other posts in this thread I now realize
I was wrong - the knowledge we now have that the expansion rate is probably
accelerating may violate the strong energy condition and it is not saved by
the cosmological constant. This possible violation casts doubt on the
singularity theorems - but evidently it is standard stuff these days eg
http://arxiv.org/abs/gr-qc/9705070 (but it is just one example of many that
can be found where this condition and hence the validity of the singularity
theorems has been called into question).

Thanks
Bill

>
> Thanks
> Bill
>
> and therefore
> > one of the basic assumptions of the singularity theorems has failed. So
we
> > cannot be sure, if singularities truly form in the real physical world,
> > because the mathematical solution space of GR encompassing the real
> physical
> > world is outside the mathematical solution space of space-times, where
the
> > singularity theorems can be applied.
> >
> > And: I don't consider Maxwell incompetent at all. Contrary to your
> > allegations I haven't set up any criteria, by which Einstein, Maxwell,
> > Hawking etc. can be classified as incompetent. In fact, all of these
> > scientist are very competent people, who deeply understood what they
were
> > doing! My point is merely, that not *everyone* who calls himself
> relativist,
> > and who goes boasting around what great understanding of GR he has,
truly
> > has the broad understanding that he thinks he has.
> >
> > [snip..]
> >
> >
> > > Special relativity is nothing more than a theory of geometry and is
no
> > > less self-consistent than euclidean geometry. While I assume that at
> some
> > > level, relativity will not really be meaningful except as a limiting
> case
> > > of some quantum theory, that is not the level at which the whining in
> this
> > > newsgroup occurs. The people whining about relativity being a
religious
> > > issue don't and refuse to try to understand relativity as anything but
a
> > > religious issue. Everything seems like magic to someone who doesn't
> > > know how it anything works.
> >
> > How true.
> >
> > Let me add this:
> >
> > ... and everything seems clear without doubt to someone who thinks he
> knows
> > how everything works.
> >
> >
> > Best MP
> >
> >
>
>

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