negative mass

A form of mass that repels, not attracts.
Expressed as: -1 kg

Guy 1: I'll put negative mass in my friend's bed so he can't sleep.
- later -
Guy 2: WHY CAN'T I GET IN MY BED?!?!?!?

by themastermcadochemist March 14, 2020

Negative Mass and Anti-Mass

Hypothetical forms of matter that would respond to forces in reverse—push them, and they accelerate toward you; pull them, and they accelerate away. Negative mass would violate everything we know about physics while enabling reactionless drives, warp bubbles, and perpetual motion machines. Anti-mass is even stranger, potentially canceling out normal mass and creating all sorts of paradoxical effects. Neither has ever been observed, and most physicists suspect they're impossible. But the math allows them, and where math leads, dreamers follow. Negative mass and anti-mass are the ultimate engineering fantasy: materials that would let you build starships, time machines, and devices that make your commute actually enjoyable. They're also the ultimate scientific cautionary tale: just because you can write an equation doesn't mean you can build a thing.

Negative Mass and Anti-Mass Example: "He claimed to have synthesized negative mass in his garage, proving it with a video of something moving the wrong way when pushed. The video was blurry, the methodology was absent, and the object looked suspiciously like a balloon on a string. Negative mass remained in the realm of theory, where it could be as wonderful as imagination allowed."

by Dumu The Void February 16, 2026