Is it possible for variable speed of light in a vacuum?

[kissfire]

TL;DR Summary

Here is a paper which proposed the possbility and provided some evidence.

<unacceptable reference deleted>

As our universe is expanding, that is, our vacuum is becoming more and more sparse, I believe it is possible that some key characterics of our vacuum is also variable.

 

[PeterDonis]

Here is a paper which proposed the possbility and provided some evidence.

This paper looks highly questionable to me. The author is not a physicist and does not appear to understand the physics being used.

A good review by physicists of research into the possibility of variation in the fine structure constant (which is what "variable speed of light in a vacuum" actually means physically; the fine structure constant is the relevant invariant quantity) is here:

https://arxiv.org/abs/astro-ph/9803165

The bottom line is that no variation over time of the fine structure constant has been found, from today back as far into the early universe as we have evidence.

As our universe is expanding, that is, our vacuum is becoming more and more sparse

No, it isn't. The density of dark energy is constant; it does not decrease as the universe expands.

 

[Dale]

Summary: Here is a paper which proposed the possbility and provided some evidence.

<unacceptable reference deleted>

This paper is not an acceptable source. It is not even listed in either the Clarivate MJL or the Eigenfactor databases. It does not have an impact factor but advertises a high impact factor based on a Google search impact factor. It claims to be peer reviewed but promises publication in 2 to 3 days. It has all of the hallmarks of a predatory publisher and we do not support such unethical practices.

This thread is closed.