Has Lightspeed Changed Over Billions of Years?

  • Thread starter Anders Lundberg
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In summary: Physics DepartmentIn summary, the article discusses the possible changes in the speed of light over time. Observational evidence suggests that this speed has not changed in the last few billion years. There are experimental ways to test theories with varying speeds of light, and one consequence is that the electromagnetic coupling constant alpha (which determines the spitting of spectral lines) varies. However, I am not sure how large space was at the time of the initial Inflationary Period, so I cannot calculate its expansion velocity.
  • #1
Anders Lundberg
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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 o:) 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 )
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?
 
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  • #2
Anders Lundberg said:
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?
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 [itex]\alpha=e^2/2\epsilon_0 h c[/itex] 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 [itex]\alpha[/itex].
 
  • #3
hellfire said:
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 [itex]\alpha=e^2/2\epsilon_0 h c[/itex] 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 [itex]\alpha[/itex].

for example;

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

on astro-ph today.
 
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  • #4
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
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
 

FAQ: Has Lightspeed Changed Over Billions of Years?

What is the meaning of "c" in this context?

"c" in this context refers to the speed of light, which is a constant in physics and is denoted by the letter "c".

Why is it irrelevant to ask if "c" changes?

As mentioned, "c" represents the speed of light, which is a fundamental constant in physics. It has been extensively measured and has been found to be constant in all reference frames. Therefore, it is considered a universal constant and it is irrelevant to ask if it changes.

Can "c" ever change?

Based on current scientific understanding, "c" is considered a universal constant and is not expected to change. However, there are some theories that suggest the possibility of "c" changing in extreme conditions, such as in the early universe or near a black hole. Further research and evidence is needed to confirm these theories.

What are the implications if "c" were to change?

If "c" were to change, it would have major implications on our understanding of the laws of physics. It would require a significant revision of many fundamental theories, such as Einstein's theory of relativity. It could also have practical implications in fields such as astronomy and telecommunications, where the speed of light is used in calculations and measurements.

Is there any research being done on the possibility of "c" changing?

Yes, there is ongoing research on the possibility of "c" changing. Scientists are constantly conducting experiments and observations to test the constancy of "c" and to explore the implications of a changing "c". However, at this point, there is no conclusive evidence to suggest that "c" does indeed change.

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