Re: Hawking says he's solved black-hole riddle

From: Edward Green (spamspamspam3_at_netzero.com)
Date: 07/17/04 

Date: 17 Jul 2004 04:01:09 -0700

sbharris@ix.netcom.com (Steve Harris sbharris@ROMAN9.netcom.com) wrote in message news:<79cf0a8.0407161459.d0cdd72@posting.google.com>...
> MrPepper11@go.com (MrPepper11) wrote in message news:<57cfd534.0407150645.67749d9b@posting.google.com>...
> > 15 July 2004
> >
> > Hawking changes his mind about black holes
> > Physicist plans to pay up on long-standing bet.
> > Mark Peplow
> >
> ...
>
> > Hawking's original view follows Einstein's general theory of
> > relativity, which predicts that, at certain locations in space, matter
> > collapses into an infinitely small and dense point, called a
> > singularity. The theory says that the force of gravity at this point
> > is so great that nothing, not even light itself, can escape, hence the
> > term 'black hole'.
> >
> > Because the singularity is infinitely small, it cannot possibly have
> > any structure and so there is no way that it can hold information. Any
> > data about particles entering the black hole must be lost forever.
> >
> > The problem is that quantum theory, which describes space and matter
> > on very tiny scales, contradicts this. Quantum theory says any process
> > can be run in reverse, so starting conditions can theoretically be
> > inferred from the end products alone. This implies that a black hole
> > must somehow store information about the items that fell into it.

This argument painted with such broad strokes as to hardly rise to the
level of logical tension. Aside from Steve's comment, below, we don't
expect general relativity to survive unification with quantum theory
unchanged to arbitrarily small lengths. So why do we even argue about
alleged difficulties on a level where one theory involved is obliged
to fail?
 
> I don't know how this mythology ever got started about no information
> being lost in quantum processes. Real quantum processes become
> irreversible when the state is observed. Real events correspond with
> wavefunction collapses, and that doesn't require an intelligent
> observer, apparently. Things just "decohere". When they do, you lose
> information about the initial state, because any number of initial
> states can result in the state you get. Any process that can happen by
> many routes is fundamentally irreversible because of this information
> loss. That's one reason for entropy increase (though maybe not the
> only one). Information isn't just hidden somewhere as a quantum system
> evolves-- it's GONE. Gas molecules expand into a larger space and it's
> not like billiard balls. They're waves. Once you see them, you don't
> KNOW where they've been, because in a sense they haven't BEEN anywhere
> in particular, between the time they started out, and when you saw
> them finally.

This model of information loss during measurment is linked to the
Copenhagen interpretation. It wouldn't occur in MWI, for example. I
happen to be inordinately unfond of the MWI, but I don't think those
are the only two logical possiblities.

The Copenhagen picture focusses on an isolated part of the universe,
"the system", which undergoes information destroying changes during
physical processes called "measurements" under the vague influence of
the remainder of the universe, lumped into "observer". The MWI at
least has the virtue of reminding us that this is an idealization.
There in fact is only one universe, and one ongoing stream of physical
process, not neatly partitioned into "system", "observer" and
"measurements" -- however useful this division may be in certain
circumstances.

Besides by the all the normal hampers, debate is hampered here by the
slogan that hidden variables have been ruled out by the Bell/Aspect
line. I harbor doubts that this line of work has even shown what it
is capable of showing (a species of non-locality), but we don't even
have to go that far to challenge a claim that hidden variables (which
would be intimately related to the ideas of information loss or
preservation in physical processes) are dead: nothing of the sort
follows from any conclusion the Bell Ansatz is capable of enforcing.

On another note, we should be careful to distinguish two senses of
"information" here. You mention entropy increase, which corresponds
to a macroscopic or descriptive loss of information; yet the black
hole argument alleged above, and the Copenhagen picture represent a
microscopic loss of information.

> The next issue, is that even aside from quantum information loss, we
> could have guessed that black holes, once we knew they evaporated,
> would evaporate into something which contains all kinds of
> non-traditional information about how they were formed. If not, you
> have to give up lots of quantum number conservation laws which are
> dear to particle physics. Not only baryon number, but lepton number
> too. Because black holes are supposed to have only mass, spin, and
> charge, but not particle conservation quantum numbers.
>
> In a thought experiment, you can take a seed black hole and then build
> it up by firing in neutrinos, or antineutrinos, or neutrons, so that
> in the end the electrically neutral hole is made up mostly (as close
> to 100% as you like) of just ONE of these types of particles.
> Conventional Hawking radiation theory predicts that these three types
> of electrically neutral black holes will then decay the same-- into
> the same paricles of all types--- dispite totally different starting
> compositions. Which means that by this mechanism you can turn just
> neutrinos (say) into ANY other kind of particle in Hawking's theory,
> without need for their antiparticle. That sounds implausible on the
> face of it. And the same with neutrons, even though it's not quite so
> implausable (supersymetry allows proton decay to positrons and other
> junk, so I think that works).
>
> And I guess Hawking has finally realized this. In his hole evap
> theory, black holes are the ultimate garbage disposal. Using a black
> hole, it's possible to destroy any kind of particle and turn it into
> gravitational radiation or anything else, WITHOUT the antiparticle.
> That's very suspicious, and I don't believe it.
>
> But I've been saying it (nyah, nyah) for years. Heck, I realized it on
> my own, in 1995 or 96. And probably others did also, long before me.

Nice, Steve!