# Do photons age?

1. Jun 11, 2009

### DB Katzin

In another post there is an example of a vessel moving close enough to the speed of light that the journey to the galaxy Andromeda 2.5M light years takes only 4 hrs on the vessel's clock. In its own frame of reference the vessel is moving just above 600K LY/hr. Yet a photon that left at the same instant would arrive before the vessel and always be measured as traveling at velocity c with respect to the vessel. As the velocity of the vessel S/T approaches the speed of light T (actually delta t) approaches 0, ie the 2.5 M LY trip takes, 3 hrs, 1 hr, 1 minute, 1 second, etc as v approaches c. At c, T (delta t) = 0, for all distances S, implying that time does not exist for a photon. In the photon's frame of reference its arrival and departure and the trip in between are simultaneous, its velocity is effectively infinite and since no time passes it doesn't age no matter how "old" it is--how long ago it was emitted.

Last edited: Jun 11, 2009
2. Jun 11, 2009

### HallsofIvy

Yes, time does not exist for an electron, it does not "age".

Last edited by a moderator: Jun 11, 2009
3. Jun 11, 2009

### clem

"In the photon's frame of reference"
This does not exist.

4. Jun 11, 2009

### Coto

Space also becomes a point.

5. Jun 11, 2009

### Rasalhague

Why doesn't space become a two dimensional surface, given that length is only contracted along the direction of movement?

6. Jun 11, 2009

### Coto

I was just ragging.

IMHO, the ideas of length and time contraction breakdown for photons. But that's just an opinion with no justifying science behind it.

Edit: Sweet, that was my 100th post.

7. Jun 11, 2009

### Staff: Mentor

The photon's frame of reference is non-inertial and poorly defined, but the spacetime interval between any two events on the photon's worldline is indeed 0. You cannot really say that this interval represents either proper time or proper distance since it is neither timelike nor spacelike.