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Anti-gravity: impossible based on known physics. Artificial gravity: doable, just make it spin.
“Gravity is a mysterious phenomenon that we’re only beginning to understand and will likely never master, baked into the very fabric of the universe. But we can almost perfectly simulate it by spinning real fast :)” will never not be funny to me.
Spinning is definitely a close cousin to gravity but objects in a spinning reference frame don’t fall straight down. Whereas water poured on earth will fall straight down towards the gravitational center, water in a spinning gravitational reference frame will arc. So, definitely close, but not a one to one approximation.
You just have to make the spinny thing bigger!
Dark Energy has entered the chat
Even theoretically, we have no prospects for manipulating gravity. No way to, say, generate a gravitational force without a lot of mass or remove the gravitational influence of a large mass. The closest we can get is tricks like using freefall-like motion to simulate microgravity within Earth’s gravitational field. Or (and I don’t think this one’s been done, but it’s theoretically pretty straightforward, if involved engineering-wise) using rotation to mimic the effects of gravity in microgravity. I suppose one could also argue that being in orbit simulates microgravity even though you’re well within the gravitational influence of Earth. Oh, I guess I can also mention that people training to be astronauts sometimes train underwater because that simulates some of the conditions of microgravity. But yeah. The closest we come to what you’re asking about is “tricks”.
Feels like not far.
The other two answers are spot on, so all I can add is how annoyed I get when sportscasters says someone is defying gravity. There are not, in fact, the parabolic arcs that skaters and snowboarders travel are defining gravity, not defying it. Hang time is a myth, 32 feet per second squared isn’t just a good idea, it’s the law.
