nathanm@hp-pcd.UUCP (03/18/84)
. Although gravitons have yet to be sighted, they are believed to be the "particles" through which gravity acts, just as photons function for the electromagnetic force. Gravitons, like photons, would travel at the speed of light, so the effects of your instaneous black hole would take a while to reach us. Nathan Meyers hplabs!hp-pcd!nathanm
crummer%AEROSPACE@sri-unix.UUCP (04/16/84)
From: Charlie Crummer <crummer@AEROSPACE> Gravitons, disturbances in the field, are supposed to travel at the speed of light. Einstein's theory, being a gauge theory, is non-local, however. You can think of space as being prepared (Are you listening, John Cage?) by the existence of masses. This prepared space reacts locally instantaneously to local phenomena, e.g. rotating water buckets. --Charlie
leon@hhb.UUCP (04/25/84)
Geneerally, Gauge theories are local quantum field theories.
This does not mean that distant locations are not affected, but rather
that they are affected only through a signal propagation mechanism.
In terms of the formulation of field theory through lagrangian densities
this means that only a single space-time location appears in the
lagrangian. Thus:
df(x) df(x) 4
----- . ----- + f(x)
dxi dxi
is local(xi is x - sub i, summation convention in effect), but a
lagrangian like:
df(x) df(x-y) 2 2
---- . ------ + f(x) . f(y)
dxi dxi
would be non-local. For a historical perspective on this issue,
one could study the history of field-theoretic descriptions of
weak interactions(fermi lagrangian vs. the weinberg-salaam model).
By the way, classical maxwell electrodynamics is also a gauge theory
(although it is an abelian one unlike gravity). Needless to say,
electrodynamics is local.
Although the quantization of gravity is by no means a finished program,
much work has been done on it - most recently in the context of path
integral quantization of gauge theories.
leon gordon
decvax!philabs!hhb!leon