Is it possible to go below Zero-Gravity?

Answer 1

Certainly. Gravitational force is a vector. If you travel from earth to the moon, downward gravitational acceleration starts at 1g, then decreases to zero, and ends at -0.1654g.

Answer 2

Yes it is: first off, negative G's are experienced by accelerating toward the centre of a gravitational field faster than a free-falling object. But more interestingly, in a tiny sliver of a fraction of a second after the Big Bang (according to theory, this has never been proven experimentally) the Higgs boson created a field which was stretched into a negative-energy state. Since the Higgs particle is supposed to communicate gravitational forces, the negative-energy field was equivalent to a colossal expansion force that enlarged the universe from about the size of an atom to the size of the modern solar system in about 10^-30 seconds — far, far faster than the speed of light. This negative energy field was unstable, so it snapped back to a positive energy state and released immense amounts of energy, that condensed into matter and — poof! — there was the beginnings of the universe.