My music taste has expanded and changed quite a bit since I was in HS. Some of the things I liked then still hold up, but I would NOT have liked the things I do now when I was in highschool.
I'm assuming you are thinking that time is the 4th dimension and we have time here so we are 4d?
Time may be the 4th dimension, but in our universe, time doesn't actually behave like a proper dimension. For one thing, dimensions should be spatially perpendicular to each other and time is not. We also seem to only be able to move one way through time whereas we can move back and forth through the other 3 dimensions.
Dimensions get weird and complicated. For the intents and purposes of this conversation it's correct to say that the universe were experiencing now is 3 dimensional.
People don't "rot" in US prisons. For the right person it could be hell, but for most people, they just kinda get used to it over time and return to their base level of happiness. It's not a great place to be but most people would prefer it over death.
He wants AI to become strictly regulated so no one can catch up to his stagnating bullshit engine.