High Speed - Lights
High Speed - Lights (Photo credit: Wikipedia)
This is the most mind blowing implication of relativity, in my opinion. Time slows down as things approach the speed of light. At the speed of light, no time passes. Photon travel at the speed of light. Therefore, photons exist for no time, because the entire duration of their existence no time is passing.

Photons are generated from some electrical shift in an atom, and when they are absorbed by an atom, they causes an electrical shift. So, from the perspective of a photon traveling from the sun to the earth, what's really happening is there is an electrical shift in an atom on the sun that instantaneously causes an electrical shift in an atom on the earth.

I don't recall when/where I first read/realized this. But now I like to think of the speed of light as actually being the speed of time.