Asri-unix.968
net.space
utcsrgv!utzoo!decvax!ucbvax!C70:sri-unix!ES@MIT-MC
Wed Mar 10 21:26:57 1982
Various cosmological comments
1. How do we know that the known laws of electromagnetism apply on a
cosmological scale? I will try to remember to research this question
next time I'm at the Stanford physucs library. Somebody remind me
if I don't respond for a while.
2. Are the laws of physics invariant with respect to the observer's
velocity? Well, no counterexample is known.
3. In an experiment in which a radar beam passed near the sun, did
its velocity differ from c as passed the sun? Removing from
consideration the index of refraction of the interplanetary plasma,
the speed of light is always c. Experimentally, the transmission time
from Earth to satellite to Earth was measured. The result was
consistent with the general theory of relativity, but inconsistent
with, for example, special relativity plus Newtonian gravity.
The general relativistic interpretation is that the sun curves the
surrounding space, and thus alters the optical path length. One
could try to claim that the speed of light was altered, but then
one can just as well claim that the Earth is the center of the
solar system; neither assumption contradicts experiment, but just
needlessly complicates the theory.
4. A very serious problem with the "bubble in de Sitter space" theory
of the origin of the universe is that it requires the de Sitter
space to have existed in a metastable state for the infinte amount
of time preceeding the formation of the bubble.
5. This de Sitter space theory is not radical enough to have any bearing
on the "Anthropic Principle". This princlple, apparently first
expounded by John Archibald Wheeler, permits the existence of all
possible universes. Those universes suited to the development of
intelligence will be the ones observed to exist. At a lecture at
Harvard many years ago, Wheeler said that one of his students had
computed that organic chemistry type life could not exist if the
fine structure constant were more than about 1% different from its
known value. There is good evidence that the fine structure constant
is the same far away as it is here, for a change in that constant
would affect atomic spectra in a manner that could not be explained
by redshift. We do not have a physical thoery to explain the value
of the fine structure constant, so it is possible that there is no
explaination for its value. Then the anthropic principle comes to
the rescue and tells us that if its value were different, we would
not be here to measure it.
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