On Thu, 1 Dec 2005, megalegoland@yahoo.fr wrote:
Interesting. I wonder how evidence could even show that. What amount of redshifting (in %) would correspond to traveling away from us at the speed of light?
We can't speak of a percentage, the amount of shift would correspond to the velocity of the object, also if a quasar is travelling away from us at the speed of light, the emitted light would never reach us.
Please. Something travelling away from us at speed v and emitting waves of frequency f at speed c, will sound like it's emitting frequency (c-v)*f. If it's going straight away then it's (c+v)*f.
Thus, although there's a limit to the amount of "blue shifting" that can occur (it can only go up an octave), the amount of red shifting can happen for as many octaves as you want, because an emitter can theoretically get to speed of light minus any positive (nonzero) constant.
An emitter travelling away at almost the speed of light would produce extremely low frequencies many octaves below. This could make a source of X-rays be heard as AM radio interference down here, if it happened.
My point is that you can get arbitrarily close to 100% of redshifting, so no amount of redshifting is important enough to not be attributable to the Doppler effect, unlike what was suggested in this thread.
Mathieu Bouchard - tél:+1.514.383.3801 - http://artengine.ca/matju Freelance Digital Arts Engineer, Montréal QC Canada