If, somehow, an experiment created conditions in which gravitational mass turned negative, that would likely violate fundamental physics laws, and things would get weird — fast. For instance, if there were a negative gravitational mass particle and a positive mass particle in proximity, one would be attracted to the other, while the other would be repelled. So one particle would essentially chase the other one forever, reaching infinitely high speeds, Forbes said.
That's the most interesting paragraph I've read in some time.
Particles in perpetual motion, and the subsequent energy that could be generated from that would be true zero point.
On the other hand, good luck with that negative gravitational mass.