Does antimatter fall…up?
Nope. Sadly, antimatter particles don’t have negative mass. They have the same mass as their matter counterparts. It’s only other qualities (like charge) that are reversed.
That probably tells us something deep about the quest for quantuum gravity, but don’t ask me. I got a B in quantum mechanics.
enolancooper, are you referring to an actual measurement? The reason I ask is that some years ago (maybe ten?) a first actual measurement of which way antimatter falls was being planned, but hadn’t happened yet. I never heard whether the measurement ever took place.
I meant to address Podkayne in my post above.
Er, well, the same theory that predicts that antimatter should have negative charge relative to matter predicts that its mass should be positive. Antimatter is generally produced particle-by-particle, and the particles on their own are subject to magnetic and electric fields that are many orders of magnitude stronger than the force of gravity.
I did some clicking around online and found that Thomas J. Phillips at Duke is working on making a beam of neutral antimatter atoms, anti-hydrogen, that won’t be deflected by magnetic and electric fields, and fire it horizontally for a long distance and measure the deflection due to gravity.
It would “break” general relativity if it turned out that antimatter=>antigravity. But that’s what makes it an interesting project, I guess. It’s not an easy experiment to do, so it’ll be interesting to hear if he gets any good results.