[AGarvin]

I think it goes something like this:

Assuming we're talking within the framework of special relativity, the photon experiencs zero time, in other words, from its point of view it gets there instantly.

It has to do with the concept of spacetime separation as defined by the metric:

dS^2 = c2 dT^2 - dX^2 - dY^2 - dZ^2

where dS^2 is the spacetime separation between two events, c2 dT2 is the time dimension and dX^2 - dY^2 - dZ^2 are the spacial dimensions. This metric will give either a positive, negative or zero result. The time is the proper time experienced by an observer travelling between these two events.

If the time component is greater than the spacial separation, you get a positive result and the two events are causally connected (known as a timelike interval). If you get a negative result, the spacial distance is greater such that not enough time will pass between the two events to allow them to be causally connected (a spacelike interval).

If the answer zero, the events have a lightlike interval, often refered to as null. This would be like two events occuring one light year and one year apart. In the case of the photon from the Sun, the travel time is ~8.3min and the distance equally ~8.3 light min, so the interval is lightlike and the proper time interval experienced by an observer on the photon would be zero.

DOH, hope I've got that right after that ramble.

Andrew