I'm reading Stephen Hawking's "A Briefer History of Time". In it he says that antiparticles can be thought of as regular particles going back in time. Assuming that's true, it logically follows that antiparticles should have antigravity instead of gravity. Do they?

Gnomon

Antiparticles have opposite electrical charge, but the same mass, as their particle counterparts. They don't have antigravity. Jul 27 06, 4:46 PM

PaleBlueDot1

gravity's supposed to come about because of gravitons. If it was going backwards in time, it wouldn't be emitting gravitons, but it would be sucking them up (or the opposite of what it may be), right? Jul 27 06, 7:34 PM

starNumberA399

Mass and time are not related, therfore going forward or backward in time does not affect mass or gravity. Jul 27 06, 8:23 PM

peasypod

If I saw you going backwards in time, I might find some things about you strange, but not your mass. It is the same with the particle-antiparticle interchange. Some things (like electric charge) reverse for the antiparticle, (a negative charge going back in time, would appear deflected like a positive charge going forward in time), while other properties (like mass) are invariant. Jul 28 06, 1:55 AM

Baloo55th

They haven't actually proved the gravitons yet. On the subject of which, if something keeps emitting them, where do they come from? (And whur do 'ee go?) Jul 28 06, 4:44 AM

PaleBlueDot1

Wow. There are still so many of the same people around here. I guess I'll "come out"... I'm TheAlphaWolf, remember me? :P Well... mass is related to gravity, which is related to time in the sense that gravity "slows" time down (I know this is relative and there isn't an objective way to measure this... but the point is that gravity affects time)... so why doesn't time affect gravity/mass? And you have a good point baloo... and also... if gravitons are being emitted, how is gravity an attractive foce? You'd expect things to be sucked in, not being emitted. Jul 28 06, 8:41 PM

peasypod

Well, well, well, Luis, I've have been wondering you know.....you do have a certain, um, style of writing... Well, you can have an attractive force through a particle interchange (the electromagneitic force interchange particle - or boson - is the photon, which can provide an attraction). There are relativistic time dilation effects due to the gravitational field. However this is something different than saying that mass is "time-interchange invariant". Jul 28 06, 11:17 PM