Re: Faster Than Light Travel - Reply

   >be instantaneous? <
   >Nope. Last I heard, gravity waves move at C, just like EM radiation.
   Don't know about that but I have a feeling I would disagree. I seem
to
   remember an experiment that attempted to measure gravity waves failed
   pretty much. Something about measureing a very long pole's position
with a
   laser.  Whether that means gravity waves don't exist or the
experiment
   didn't work, I don't know. I have a feeling that if gravity did
propogate
   at C, the expanding universe theories I hear so much about would have
big
   problems. Part of the big bang theory is based on the fact that all
bits
   attract all other bits propotionate to mass, regardless of distance.

Ok, gravitational waves move at the speed of light.  Gravitational
waves are ripples in space-time caused by masses moving around.
Stationary masses do not (NOT!) cause gravitational waves.  What, you
say?  Well, remember, stationary charges do NOT cause electromagnetic
waves.	If charge up a pith ball, it will not start emitting light.  I
have to have it accelerate to cause radiation.	The same is true for
gravitational waves.  If I were to take the sun and start wiggling it
back and forth it would cause gravitational waves just like the
wiggling electrons in a radio antenna radiate radio waves.  

With regards to the big bang.  One of the really cool things about
general relativity is that it is a local theory.  (E and M is the same
way.)  A local theory means that a particle here -->* only cares about
what is locally around it.  The electron that are screaming towards my
computer screen to light up phosphurs only care about the E and M
fields in their immediate vicinity, they don't care about the E and M
field at the plates on the sides of the Cathode Ray Tube.  This means
that you form a nice chain.  For the big bang, this means everything
effectively acts on everything else in the universe because you can
say, something a gazillion light years away gravitationally acted on
something a gazillion -1 light years away, which then acted on
something gazillion -2 light years away, etc etc etc.

Anyway, enough physics (I am an astronomer afterall).  I suggest that
everyone with questions about this read the sci.astro FAQ.  A lot of the
things we are talking about are answered there.  The http address is:

http://astrosun.tn.cornell.edu/students/lazio/sci.astro.html

and I suggest the astrophysics section for stuff on tachyons and 
gravitational waves.  

cheers
brad