# Irrelevant to ask if c changes?

1. Jan 9, 2006

### Anders Lundberg

In the summer 2004 I read an article in New scientist discussing if lightspeed has changed during the last few billion of years. (I have also read some Creationist stuff about light being much faster about 6000 years ago, explaining why we can see stars billions of lightyears away in spite of the mere 6000 years since creation:yuck: )
My question is: Would not a change of the speed of light (or rather; the speed that not light or gravity or any other fenomena can exceed), change the speed of all chemical reactions also? Would it not change every aspect of the universe? And would not that universal change "even out" the change of the speed of light so that we will never be able to notice it?
If the increased speed of light eg. also makes clocks tick faster (or makes the space expand a bit?), then we may still measure the speed of light to be 299 792 548 m/a. In other words, do we not chase our on tail here?

2. Jan 13, 2006

### hellfire

Actually there are experimental ways to test theories with varying speed of light. One of the consequences of these theories is that the electromagnetic coupling constant $\alpha=e^2/2\epsilon_0 h c$ does also vary. This constant determines for example the spitting of the spectral lines of the hydrogen (the “fine-structure”). Comparing distant spectral lines with the ones of today might provide information about a varying $\alpha$.

3. Jan 13, 2006

### matt.o

for example;

http://arxiv.org/abs/astro-ph/0601264

on astro-ph today.

4. Jan 14, 2006

### Chronos

Observational evidence, of the kind hellfire mentioned, severely constrains any possible changes in the speed of light over time to parts per billion. If you assume the fundamental constants of nature are coupled, as I do, this is the expected result. Causality would otherwise break down at some distance/time; which is pretty much what happens at the big bang.

5. Feb 3, 2006

### Chaos' lil bro Order

space itself can exceed light speed

I've read that no particle or force can exceed C, however, there is no limit on how fast space's velocity can go. Perhaps (now I will speculate) that during the Period of Inflation (10*-36s -to- 10*-32s) when space is estimated to have expanded by a factor of 10*20 -to- 10*30 times, space actually expanded faster than C. However, since I am not sure how large space was at the time of this initial Inflationary Period, I cannot calculate its exapansion velocity during this Period.

Reference: Mark Filipenko, Berkeley