Newsgroups: sci.physics.plasma
From news@hp.fciencias.unam.mx Tue Apr 16 10:08:26 1996
From: Graeme A Stewart <graeme@tonatiuh.igeofcu.unam.mx>
Organization: Instituto de Geofisica, UNAM
Subject: Re: A Q RE: Gravity

Glac Clasher wrote:
>
> I wonder why you have the unmitigated pretentious nerve to pronounce such

Please flame to /dev/null next time, but anyway...

> an opinion as if it were factual information you were passing along and as
> if you actually knew what the time of interaction between two bodies could
> be.

Actually the time of interaction in classical GR is well known to be limited
to c. It's quite straight forward to solve the field equations for solutions
which propagate at the speed of light when the matter distribution
changes - see Rindler, "Essential Relativity" (Springer-Verlag 1977)
sec 8.8 and refs therein (I'm sure any other decent GR textbook would also do).
If you are upset with the time of interaction being limited to c don't
take such umbrage at what I wrote, but rather tell us where GR goes wrong
in describing gravity. As far as I'm aware it does an excellent job
(Mercury's perihelion advance, gravitational lensing, pulsar clock
test, etc.), but you might have some other information - please post it
if you do.

> It is more than just very likely that gravity is a non-local quantum
> force.

As far as I know no-one has managed to get QM and gravity to work together,
so any speculation here is just that - speculation. On the other hand
my statements about the finite light travel time are based on GR, which
is experimentally confirmed to be an excellent model.

> Non-local means (among other things) that the force is not
> propagated at the velocity of an EM wave. Like the Aharanov-Bohm effect
> the interaction is mediated/propagated along the potentials (not
> positionally, as in a field) and therefore takes no time to propagate.

Has this effect been experimentally verified or is it just a mathamatical
solution, which may have no bearing upon reality? (Remember, just because
you can solve an equation in a certain way doesn't mean that nature behaves
that way - tachyons are a case in point.)

> Such an interaction as gravity is related to the overlapping quantum state
> which can occur between interacting particles and overlapping quantum
> states do not propagate at a finite velocity.

Again, we have no idea what the relationship between gravity and QM is. I
could go into the whole EPR paradox question, but I'm sure you're familiar
with it. Until we can do the actual experiment we won't know for sure, but
my money's on QM as being an incomplete theory (now that's speculation and
I admit it!).

Cheers,
Graeme
--
|Dr Graeme A Stewart, Instituto de Geofisica, Ciudad Universitaria, |
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