# QM and relativity.

1. Jul 26, 2010

### wittgenstein

My understanding is that any uniform motion ( according to relativity) can be considered stationary. For example if object A is moving at a constant velocity, it is as legitimate to say that it is stationary as to say that it is in motion. Why cannot a photon, moving at the speed of light and at a constant velocity ,be considered stationary? In that case according to the photon's "viewpoint" the space it traverses is non existent. This seems to me to coincide with QM's idea of non-locality.
One more related question. Why is the speed of light 186,282 mps? Why not 186,283mps? To make my point more dramatic, suppose that photons of light in a vacuum traveled at 45 miles per hour. Would time dilation effects then be noticeable at 20 miles per hour? I would guess not ( I could be wrong, I'm not a physicist, just a curious layman) . Then, my question becomes why do photons move at the exact speed that time ( for them) ceases?

2. Jul 26, 2010

### Staff: Mentor

A postulate of relativity is that all uniformly moving reference frames are equivalent and equally entitled to be considered 'stationary'.
OK.
Since another postulate of relativity is that the speed of light is the same in all reference frames, light itself cannot be at rest in any reference frame.

3. Jul 27, 2010

### AJ Bentley

There's no reason why one can't consider a photon to be stationary.
It might be amusing to do so.
I guess that from that perspective the entire universe would contract to a two dimensional plane and time would freeze.
I've never looked into the physics of Black Holes (one day if I live long enough) but I would have thought the math involved should consider a situation close to this.

As to Light at 45mph, George Gamow wrote a book entitled 'Mr Tompkins in paperback' where he discussed this, and other concepts in detail at a popular level - worth a read if you can find a copy.

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