[jeffreyH (OP)]

One of Stephen Hawking's views was that the big bang caused an equal amount of positive and negative energy. Where is the negative energy?

[Kryptid]

I've always read that the negative energy was in the form of gravitational potential energy.

[jeffreyH (OP)]

If that were the case there would be an equivalent negative mass associated with the gravitational field. Electromagnetism could be defined as a positive energy proton and a negative energy electron. That wouldn't make it true. Negative energy is likely linked to the expansion of the universe and which is repulsive in nature.

[jeffreyH (OP)]

Another point on this subject. Choice of coordinates matter. If there are two large bodies, with a smaller one in between, and all lie on the z axis, we can define one object to be in the positive momentum direction and the other in the negative momentum direction. Relating this to potential and kinetic energies does not indicate negative energy. Negative energy would relate to mass energy.

Having E = mc^2 implies -E = -mc^2. You could say that it is a negative speed rather than the mass that gives negative energy. That is when things are moving away from each other. Hence negative energy indicates an expanding universe.