I was talking with a group of people today about a bunch of "what if" predicaments such as the ability to travel at or faster than light speed and how you could travel through time and witness the past (not your own but actually a source of light from the past) but not be a part of it, only experience it.
We also went into the perception of time, and how it's possible for animals to perceive time differently, such as a starfish, which moves incredibly slowly, perceiving it's actions to actually be moving normally. For example walking as opposed to running, theoretically, a starfish could move to one side of a rock in around a half a day's time as we perceive it, but to the starfish it could as well be jogging over to meet it. Don't just discard this theory, especially if you toke, since everyone that has, has experienced something called "Marijuana Minutes" where 2 minutes feels like two hours.
Another topic was sensory depravation, being kept in a box, with it pitch black, for an elongated amount of time, would you eventually lose your sense of time, and have either a week feel like a month or vice versa?
Feel free to elaborate on any of the above topics, or start your own
Things like:
Black Holes
Color Definition
Possibility of Alien Lifeforms
Perception of reality
Go nuts