That's why I said it only one theory. There's another really complex cosmological one. It takes into account that if v = d / t. Both v & d constant (speed of light and distance light travels) are constant, but t is not necessarily constant (b/c of general relativity). Of course that's grossly oversimplified.
I don't know what GR stands for, but I remember that this explanation of cosmology came from Humphrey.
Time is distorted by gravity according to Einstein's theories of relativity. Velocity of light is constant. Distance is constant. But time is not. Which means the time in which we supernova 1987A could be different.
edit: Wait! GR=general relativity (duh!)
This message has been edited by commike37, 01-18-2005 19:23 AM