Does the speed of light decay as it travels through space?

Question

Or light itself?

Answer 1

If the speed of light did not stay constant, than physics would not be the same in different frames of reference.  If we could get light to go slower, we would have time machines; at lest theoretically.

Answer 2

Nash is pretty much right.  When a light beam passes by a massive body, it is deflected, but the speed does not change.  Einstein teaches us that the speed of light in a vacuum, anywhere in the Universe, will be the same EVEN IF THE SOURCE OF LIGHT IS ALSO MOVING.  This is the very fabric of relativity, which is proven to be accurate to within several thousand decimal places.

Answer 3

no

Answer 4

To the best of my knowledge the speed of light never changes. It's basically the universal speed limit.

Answer 5

I think gary B is wrong.  I believe light can be bent by gravity, that is to say its direction can change but I don't think gravity changes its speed.

As to Decay, As you get further and further from a light source the photons hitting you are fewer and fewer but I don't think their speed changes. But I'm no expert. I could be wrong.

Answer 6

I would make the argument that it does.

The speed of light IS affected by gravity.  We can prove that.  

Now, if we were to send out a single photon of light, it would head off in some direction, presumably toward the "end of the universe".

Once it got out into Deep Space (between the galaxies) the effect would basically be that it has the gravitational effect of the whole universe acting on it, trying to pull it back, like the gravity of the earth tries to pull back a baseball.

So my guess is that  it WOULD slow down (decay). Moresoe if it travels near a galaxy, and in that case it would also curve its path.

Answer 7

No, because light is constant.  Which means that no matter what speed you go light is always coming to you and leaving you at the speed of light.