That depends on whether, by “attraction”, you mean the force or the acceleration. If I let go of a negative-matter baseball, it would feel a gravitational force upwards, but that upwards force would cause it to fall downwards.
And gravity propagates at exactly c.
Didn’t Dan Simmons use an idea like this in his Hyperion novels? It’s been a while since I’ve read them, but I seem to recall that there were a few characters who were moving backward in time. I couldn’t get my brain around the concept then either.
Actually we’re moving through spacetime at the speed of light, and that’s because the magnitude of velocity four vector equals c. In other words if we’re stationary in space then we are moving through time at c, and if we are stationary in time then we’re moving through space at c. (The last is obviously impossible unless we are photons)
Is it negative mass or is it matter with a negative energy density? If it’s the latter then we can get a little of it between Casimir plates.
Sorry alimarx upon rereading your post I see that that’s what you said.
OK, you invent a machine that can reverse the flow of time. But while you were building the machine over the years, you notice a strange lump of metal in the backyard. Slowly the metal begins to resemble the wreck of a car. You go out back and notice a dent in the car. You take a hammer and pound where the dent is, and the dent disappears. After a while the car is whole and new, in fact almost brand new, a Cadillac. But the car won’t run. You walk to the car dealership and notice an identical car, buy it and drive it home. Finally you finish your time-reversal ray. You clamp the wheel still, weight down the accelerator and point it at the mystery car, and step out. The car jumps forward. Suddenly the mystery car jumps backwards and both cars are racing towards each other. Quickly you get out your time-reversal ray and point it at the car. Just as they are about to collide you pull the trigger and they both vanish in a blast of energy equivalent to a thousand nuclear bombs.
Car and anti-car, just like particle and antiparticle.
Whoah.