Interesting thread idea...
When I'm high I think really deeply into interesting things. Like time. I don't really have any background education on stuff like the theory of relativity and whatnot, so a lot of what I think about probably already has a few answers. Lately, I've been thinking about how time is totally perspective, and that it doesn't exist in a constant state. What sparked this idea was just one day I looked at the clock at work, and it seriously felt like an hour had passed, when only TEN had passed, and I was totally baffled and it made me temporarily question my sanity. And then I started thinking about how bizarre that is, and how psychedelic drugs (not to mention other drugs; but these, I think, on a higher level) (LSD, shrooms, salvia, DMT, etc.), are all known for their time-distorting effects. I remember a few of my earlier shroom trips I made the mistake of looking at the time frequently, which totally blew my mind because of the time-distortion. Now I always take off my watch when I trip. I also never look in the mirror because I always have this really cool, residual image of myself and don't like to ruin it by looking at what I ACTUALLY look like XD. Anyway, people have also described their trips on more powerful psychedelics like salvia as feeling as if thousands of years had passed. And so that got me thinking that time is really just a feeling that we recognize naturally as a species. Etc...
ANYWAY, that's just a taste of some of the ranting I could go on to now, but I won't, for everyone's sake.