According to the Lorentz factor from Special Relativity, time grinds to a halt if v=c (i.e. if something goes at the speed of light)
Well, *light * goes at the speed of light (at least in a vacuum), so for a photon, time does not pass.
Is this a valid statement?
If so, the following this should be true
Even if photons have a half-life, they will never decay, since no time ever passes for them
A photon can whiz around an entire galaxy in zero time (at least in its frame of reference, since time does not pass for a photon). That means that the distance between any two points in the universe seems to be zero, at least to the photon because it gets from any point A to point B in zero time.
So, to a photon, the size of the universe is zero.
In essence, from a photon’s perspective, the universe is still at the moment of the Big Bang, when the whole universe was concentrated in one point.
Anyway, some thoughts I’ve had for some time now, and I wanted to see what people knowledgeable in the subject might have to say.
I was going to mention that photons do experience changes–like frequency changes, etc.–but then I realized that this isn’t exactly true; most of these “changes” are from photons being re-emitted after interacting with matter, so essentially you have a new photon.
But the fact is that photons are created and destroyed (by being absorbed by and emitted by matter) all the time. So we can at least say that photons have different lifespans. So there should be a beginning and an end to their experience of time, if not a middle. So perhaps, rather than their time being stretched to a standstill, it is in fact compressed to an instant, where they are destroyed as soon as they are created (those lucky ones that hit matter).
Photons are indeed timeless. One good way to think about it is that everything always travels at exactly the same speed though spacetime - the speed of light. Large objects like ourselves travel fairly slow though space, and we travel quickly though time, so that our total velocity though time and space is equal to the speed of light. A photon travels at the speed of light though space, and thus doesn’t travel at all though time.
I’m not sure though that the universe would appear as zero space and zero time though. They are without time, not of zero time. So I would guess that to a photon, they would be a timeless straight line, with one end being the event that generated them, and the other end being the event that absorbed or destroyed them. The universe around them would be unchanging timeless space. I think. I’m not a physicist so i may be completely wrong.
I don’t think it has a “factual” answer, as I think there is a lot of conjecture as to what light really is, and how it behaves.
In any case, there haven’t been many responses to this question from actual physicists, so maybe moving it to GQ might be a good idea if it resulted in more responses from physicists.
I don’t see how that’s possible. Photons are created and destroyed all the time. When a photon hits a surface and is absorbed, it’s destroyed. When you take an electron and shake it, a photon appears out of nowhere (well, from the energy you expended to shake it).
Perhaps you are thinking about the “theory” that positrons are electrons travelling backwards in time, and therefore all electrons are just one electron travelling back and forth in time?
I don’t think this question really has an answer. A photon, of course can’t think, so what you’re really asking is “what would the world look like if I could ride along with a photon?” But you can’t: special relativity guarantees that anything with mass always moves slower than light. AFAIK, there’s no way to build a sentient being out of photons, so we will never be able to ask what it’s like, either.
