From the point of view of a light particle/wave, is time stopped completely? If so, does that mean that from that point of view, it exists everywhere simultaneously?
Yes, in the way that you are probably thinking. If you were a particle of light, you would have the sense of time moving normally but it would look to you like the whole universe was frozen in time.
Well, from a quantum standpoint I believe there would be a nonzero probability that the particle would exist at any given point, but I don’t think that’s what you’re getting at. When an object speeds up it does not cause it to exist in more places, so when it hits c it does not exist everywhere. Not quite sure what your thinking is on this one.
Yup. Light never grows old. Time “slows down” for the observer when moving faster, reaching infinite slowdown at the speed of light. Since a photon by definition moves at the speed of light, as far as the photon is concerned no time ever passes no matter how far it goes. You might think that sounds just jolly if you’re used to commercial air travel. No travel time at all! Wow, I’m in Hawaii - I was just in Cincinnati! This is great! That’s not the whole story, though. As you approach the speed of light, distances are also compressed along the axis of travel for the observer - again, reaching an infinite compression at the speed of light. So, not only does no time pass for the photon, from its perspective it’s also not moving any distance at all!
Talk about going nowhere fast.
Yes and Yes. In as much as a photon experiences anything it doesn’t experience time. There’s a Einstein thought experiment, what would a ray of light look like if you could catch up with it? A stationary magnetic wave. It’s not moving. It’s unchanging. Frozen. Stationary.
Anyone care to put the Maths on that?
In any case, I think I got that about right. Feel free to slap me with a trout and correct any mistakes in that reasoning.
There’s also an Einstein thought experiment. Sorry about that.
A stationary electro-magnetic wave. I’ll get this right eventually.
Yes. Time is not moving normally as CookingWithGas stated. There is no time.
No, it means that a photon has no internal existence. It appears and disappears in no time at all from its internal frame. That’s not something easily imaginable by anything with mass.
To sum up, neither “space” nor “time” really means anything to a photon.