On 24/06/2013 12:44, Davoud wrote:
Ben:
There are some intriguing and attractive ideas in this article:


http://www.newscientist.com/article/...ntanglement-so
lve
s-black-hole-paradox.html#.UcYTrfnVD6e

Davoud:
It begins with an explanation of what a wormhole *is* but wormholes are
not known to exist. Then it builds on that untested (and untestable)

Martin Brown:
It isn't in principle untestable although it would require engineering
well beyond anything that we can contemplate just to visit a large
enough black hole. Most theoretical physicists don't like the idea of
having a naked singularity from a maximally spinning black hole.

http://en.wikipedia.org/wiki/Naked_singularities

conjecture. It's a bit reminiscent of string "theory." Turns out if you
know some math you can pick one of the 10E500 string theories and run
with it and no one can prove you right or wrong. Physicists so want
there to be a theory of quantum gravity, but they haven't yet found a
hint that there is such a theory outside of their own desires.

String theory might be right. Who knows? Even the best mathematicians on
the planet can't actually make any useful or novel predictions with it
as yet that are amenable to experimental testing.

That means that it's not a theory.

String conjecture is perhaps too much of a mouthful. The mathematics
might or might not describe our universe but you can still play around
with it to see if anything useful falls out.

ISTR they are not all that far off making predictions that could test
some of the specific big bang initial conditions and fluctuations as
different from conventional cosmology.

However, the observers and their instrumentation are getting better all
the time so we live in a golden age where observation evidence will rule
out some of the theorists' wilder flights of fancy pretty soon.

No, I'm not qualified to do this research myself. But I am sufficiently
science-savvy to recognize evidence when I see it, and to remain
skeptical when I don't see it.

*****

³As a conservative, I do not agree that a division of physics into
separate theories for large and small is unacceptable. I am happy with
the situation in which we have lived for the last 80 years, with
separate theories for the classical world of stars and planets and the
quantum world of atoms and electrons.² -- Freeman Dyson in a review of
Brian Greene¹s book The Fabric of the Cosmos.

It is extremely unsatisfactory to have two theories that are mutually
incompatible at the finest scales and highest energies. It is a strong
hint that there is an underlying more complete theory that we have yet
to find. Dysons approach is a council of despair. Give up on science
since what we have now is good enough for all terrestrial engineering
purposes (which is probably true, although you can never predict what
the side effects of extreme blue sky research will be).

I don't think it's possible at this time to say whether this is despair
or realism. We're approaching 100 years of trying to unite
GR--gravity-- with quantum theory, and we're no closer than we were at
the beginning; we have nothing that qualifies as a theory of quantum
gravity in the way that Newtonian mechanics, evolution, GR, the germ
theory of disease, et al. qualify as theories.

And it took over 2000 years to get from the Greek philosophers rough and
ready explanations of the universe to where we are now. You cannot
predict when the next great paradigm shift or breakthrough will be made.
It could be tomorrow or not for another hundred years or more.

No-one would have guessed at high temperature superconductors and we
still don't have any predictive theory for the maximum temperature at
which one can operate or how to construct one to order with a higher Tc.
Sometimes it requires experimentalists to suck it and see - just
occasionally they get lucky as with Magnesium Diboride in 2001 (which
drove a coach and horses through existing theoretical models)

http://www.superconductors.org/39K.htm

We may not even recognise it when it happens. Early quantum mechanics
was far too abstract an incomprehensible when first discovered to be
anything other than controversial. Today it is possible to teach a
simplified version of it at A level and a half decent formal
mathematical treatment of it to undergraduates. Times change and
knowledge increases.

High energy physicists and astrophysicists compare notes a lot more than
you might think at first sight. There is much more in common between the
two big science disciplines of ultra large and ultra small.

No, not more than I might think. I don't know with any degree of
precision the extent of information exchange between various scientific
disciplines, but there is no extent that would surprise me.

Who would have predicted 50 years ago when the very first laser was made
from a perfect synthetic ruby crystal lovingly polished and half
silvered and illuminated by a complex flash system that one day they
would find an important use at home in every consumer CD and DVD player.

You cannot tell in advance what theoretical developments in advanced
theories will lead to new insights and ways to manipulate nature.

Theories. The laser was not a stab in the dark. It was the application
of well tested theory--as was the transistor before it. I'm sure that
the inventors of the transistor and the laser were pleased that it
worked, but I don't think that they were amazed.

String theory may yet win out. I personally don't like them. I do know a
few top cosmologists including one practitioner. He is *very* bright and
so I do not rule out the possibility he might be right.

--
Regards,
Martin Brown