Dear Coyote,

Thank you for our continued correspondence. You raise two issues which I
would like to respond to:

1. Expanding universe. There are many non-expanding models of the
universe in cosmology. They are called steady-state models. Indeed, when
Einstein first developed general relativity (GR), the steady-state model was the
prevailing cosmological model in his time, and he believed in it so
strongly that he had to invent a constant, the cosmological constant, to
make GR agree with the steady-state universe. When Hubble found evidence
for the expanding universe, Einstein declared that introducing the
cosmological constant into his GR equations was the biggest blunder in his
life, because had he not so firmly believed in the steady-state universe
to begin with, he could've been in a position to predict universal
expansion years before Hubble actually discovered evidence for it.
Today, we have evidence that the universe is actually ACCELERATING in its
expansion, and some have invoked Einstein's original idea of the
cosmological constant to account for this acceleration. It's too bad that
Einstein is no longer alive to appreciate how his cosmological constant is
being used today, because he may in the end actually be right, although
for the wrong original reason.

See: http://en.wikipedia.org/wiki/Universe


2. Speed of light. Einstein's special relativity (SR) is founded upon the
experimental results of Michelson and Morely, who used interferometry to
measure light's speed. The prevailing theory at the time was that light's
speed would be different depending on the direction of Earth's motion
through the "ether," a substance once thought to permeate all of space.
Michelson and Morley's experiment showed that the speed of light is
decidedly independent of the direction of Earth's motion, thus dealing a
severe blow to the ether paradigm. Thus, Einstein proposed a radically
new idea: light's speed is actually fixed in all inertial reference
frames. Of course, at the time, no one else liked that idea, because the
logical consequence of fixing light's speed would be to make time and
space relative (hence the term "relativity"). Over the next 20 or 30
years, experiment after experiment, observation after observation
confirmed SR (and all its implications). And every single day at the
particle accelerator labs, SR is being indirectly confirmed because its
effects are much more pronounced at high energies and speeds.

See:

http://en.wikipedia.org/wiki/General_relativity
http://en.wikipedia.org/wiki/Special_relativity

Also, we who do science don't hold GR and SR as though they are our holy
grails. We recognize that they are wonderful theories which make
predictions which are confirmed to the best of our abilities, satisfying
every objective test with astonishing accuracy. It has been a century
(1906-2006) since Einstein first laid down his relativity principles, and
in this time, countless tests have been performed, all of which are
consistent with relativity. This does not say they are the final word on
this aspect of nature. Not at all ... it just says that given our current
ability to test these theories, they are verifiable and seem to say
something objective about nature. As our technology advances, we will be
able to perform more precise experiments in the future, and maybe a deeper
theory will be required to explain those measurements. This does not
"disprove" GR and SR, just as Newton's laws are not "disproved" by GR and
SR. It just says that Newton's laws, GR, and SR are fabulous ways of
looking at the world in their respective regimes where they offer
verifiable predictions. And we can confidently use these theories to
guide our way toward a deeper understanding of nature.

By the way, as I'm sure you know, there are many alternative theories
about gravity and light which researchers are developing. Some show
promise, others not. All must submit to objective experimentation to be
validated and accepted. So far, GR and SR beats them all, hands down.
That is why we prefer to use GR and SR as the current working models, not
because we have some perverted attachment to these theories based on
faith, but because the evidence speaks for itself.

Best,

HF

P.S. As I mentioned to Lord Shandor, perhaps we could start another thread
to continue the more general debate, and dedicate the current thread to
your cloud-busting theme.