system
Given the following post, respond as if you're commenting on Reddit:
human
Is there any serious research into antigravity?

I know NASA was interested in the 90s to replicate the russian experiments (superconducting rings or something similar) but I don't know if it lead to anything. Magnetic fields are one thing but is the cancellation of gravity being seriously explored?
gpt
There are three ways to answer this question.

The first is simply to say no, none at all. With the advent of general relativity, we now know that antigravity would be exactly equivalent, both mathematically and physically, to doing backwards in time.

The second is to get slightly liberal with our definitions and talk about how whatever force propels the metric expansion of spacetime is, in a very sketchy sense, an antigravity of sorts. But it only looks that way if you're very careful about choosing your frame of reference, and it's not possible to interpret the physics in any way that a reasonable person would call "antigravity."

The third is to be a complete wiseass and point out that *flight* is equivalent to antigravity, and there's plenty of research being done in that regard.