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I have read that the theory of relativity is based on two postulates,
1- that the speed of light in a vacuum is constant and not dependent on the source or the observer and
2- that the mathamatical forms of the laws of physics are invariant in all inertial systems.

But the speed of light is not a constant, for example, at time zero it was 10 billion times faster than it is today (the speed of light is decreasing/decaying) and that the laws of physics do not work in black holes, how how can it be correct?

Question Date: 2007-06-07
Answer 1:

Theres no solid indication that the inherent maximum speed of the universe is changing. Some scientists have claimed they have measured the change, or that they have some theory in which the speed of light is changing would solve some problems, but frequently they create more problems than they solve which disagree with current measurements and experiment, and so there is no solid evidence for any theory as such. In physics there is no such thing as absolute truth, only degrees of certainty. And practically all of the physics community is very certain (at least as of right now given current experiment and theoretical agreement) that the speed of light is constant.

As for laws of physics in black holes, they are actually very well preserved. If you want to think about it in a fun way, there's nothing different inside a black hole. In fact, if our entire milky way had the density of air on earth (luckily it doesn't) then our milky way would be a black hole. Theres nothing about physics that changes noticeably inside a black hole than outside, save the singularity at the center (that is an area of physics that no-one understands). however, everything outside the singularity is well understood (if Einsteins theory is correct, and it's been well-tested for awhile, as well as good observation support for the existence of black holes and the physical effects of strong gravity in objects such as neutron stars), and given Einsteins equations for gravity, it is known that inside a black hole the laws of physics are no different than outside. It is simply an enclosed area that cannot interact with the remainder of the universe. Thats what's currently thought of as true.

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