Lemme see,
Negative matter is one of those postulated exotics. It has never been seen, but it's existance is required in some cosmological models, or at least there is no known physical prohibition.
Cool stuff.
Hello M!
I was thinking of massive particles for my example, because mass is related to gravity. Photons can feel gravity in the sense that they follow curved space, but do not generate gravity themselves.
Meebe this will clear this up.. In this example a proton (could be any other massive particle you like) and a negative proton are placed close enough so each can feel the other's gravity. Cant be too close in this case, because a negative proton has a positive charge and repells the garden variety one. Now the "regular" proton senses the mass of the negative one. It falls towards it. The negative gravity of the negative particle senses the regular proton. It falls AWAY from it. One trys to capture the other and the other trys to escape. Because the force of gravity in this case is identicle, neither particle moves in respect to the other, but it does to the rest of the universe. It is a PushmePullu. Otherwise undisturbed, it will continue to accelerate, ever approaching the speed of light.
It violates no conservation of energy rules, because remember that classically, gravity is an acceleration. How much energy does the moon use up falling around the earth? What is it's means of propulsion? None. Same here.
Silverpig, Moonbeam is correct in saying there are antiphotons. A cornerstone of the understanding of particles calls for every particle to have an antiparticle. Photons, neutrons, everything.
Moonbeam has a knack for picking out the oddballs though
OK, I will give this a try. An antiparticle can be considered an "normal" particle travelling backwards in time. If an antiphoton has not interacted, it behaves in a different way than one that does. It's kinda of complicated, because it involves some abstract concepts that are not easy to give here. Look it up if you dont believe me
For most purposes, a photon is considered it's own antiparticle.
Oh, to really make your head spin, you could have an negative antiparticle
