c

I was reading Neil deGrasse Tyson's AMA on Reddit. I came across two shit-brix ways to interpret how light works.

Not for the faint-of-physics, but uses content from HSC Phys and before.

1) A photon will be absorbed the instant it is emitted, in its own frame of reference. All we have to do is rearrange the time dilation formula for t_0 to see that it's 0. I previously never considered this but this is goddamn cool.

2) I understood why travelling faster than the speed of light is essentially travelling back in time. It's because time is a relative concept that depends on the interactions with light that you are receiving. If you were somehow teleported 20 million light years away and had a sick telescope, you could observe the extinction of the dinosaurs. Although I don't get what would happen if you orbited the Earth a tangential velocity of greater than c, then reentered. I'm guessing that since circular motion is far from inertial, special relativity can go to hell, and nothing cool will happen =(.
It seems like the perfect tradeoff - if we could go >c, we would be able to view events from the past, at the expense of not being able to interact with them.