Photon & Time: Is Movement Possible?

[taylrl3]

I'm just wondering how a photon can move if it does not experience the passage of time?

 

[Sojourner01]

What makes you think it shouldn't?

 

[taylrl3]

How can anything change if does not pass?

 

[Sojourner01]

Ok, suppose we freeze you cryogenically and put you on a train. When the train moves, do you move?

Ridiculous example. But that shows what I'm trying to express here, which is that the question you asked is not a useful one. You've tried to project human assumptions onto a system which does not know or care about your opinion or how you think things 'ought' to behave. The real way to understand physics is to examine the mathematical formalism, which will then show you that questions as vague as this have no meaning.

 

[taylrl3]

Nice response. Thanks :-).

I've just been thinking about it a bit further. In the reference frame of the photon t=0 and always will. Therefore it is not the photon which moves but my movement through time which causes it to reach my eye.
Quite a nice way of seeing how space and time are so intrinsically connected, ay?

 

[taylrl3]

Sorry my first response should have said; "how can anything change if TIME does not pass?".
(I should read my messages before posting. lol)

 

[andrewkirk]

I think the answer might be that there is no 'reference frame of the photon'. If you could have such a frame wouldn't it contract space in the direction of propagation to a point, so that spacetime becomes only three-dimensional in that frame (ie loses a dimension)?

 

[powerplayer]

this thread gave me an interesting thought, which is related to the topic.

when we observe photons are we observing them with no time?

so to try to make that clearer, the closer something gets to c the slower time for that thing appears to an observer in a rest frame, so wouldn't a photon appear to be frozen in time to us?

 

[ghwellsjr]

when we observe photons are we observing them with no time?
...
wouldn't a photon appear to be frozen in time to us?

We cannot observe photons until they hit something and are detected. Detecting a photon ends its existence. Observing a photon ends its existence. Photons have no appearance while they are in transit, only when they hit something and are detected. We can measure the time at which they hit something and are detected but otherwise, there is no point in trying to determine anything related to time with regard to photons while they are traveling at the speed of light.

 

[petm1]

I'm just wondering how a photon can move if it does not experience the passage of time?

I like thinking of photons both ways, with the matter wave standing still and the photon expanding at c into it, or the photon standing still with the matter wave dilating into it at c.

"how can anything change if TIME does not pass?".

Time is local and changes are how we count it.

In the reference frame of the photon t=0 and always will. Therefore it is not the photon which moves but my movement through time which causes it to reach my eye.

The photon moves through space at c, we on the other hand must be moving in time at the same speed just to receive these photons with no gaps.

so to try to make that clearer, the closer something gets to c the slower time for that thing appears to an observer in a rest frame, so wouldn't a photon appear to be frozen in time to us?

Does a photon form an image of the past within my eye? I think of these images as my present but in some cases I see an image over a billion light years old.

 

[arkajad]

And does the electron experience the passage of time?

 

[Fredrik]

There's probably a hundred threads about this already. One of my previous replies:

For something to actually age, it needs to have an internal structure that can change with time. No elementary particles do, so they can't really age.

For something to really experience the passage of time (or anything else), it needs to be conscious. Things without internal structure certainly can't be conscious.

What we mean when we say that an object or a particle "experiences X" is that in the coordinate system that the standard synchronization procedure associates with the object's world line (or its tangent), some sequence of events is described as "X". That's how the term "experiences" is defined in the context of special and general relativity. The problem is that the standard synchronization procedure doesn't work for null geodesics, i.e. for the curves that can be world lines of massless particles. So the term "experiences" is undefined for photons.

See also this.