Hawking and Stenger

Hawking and M... 's idea is that the gravitational potential energy exactly cancels out the positive energy of the gravitating masses. In terms of energy, it is the same as having nothingness. The problem with this kind of approach is that the notion of energy is given significance only by theories of physics. So we can always ask: why should such-and-such a theory be the correct one out of so many possibilities?

Also, to argue that zero total energy (or stress-energy or whatever) is equivalent to the energy of nothingness assumes a background physical theory. Once again we would want to know why that theory obtains.

Stenger has said nothingness is unstable. By "unstable" one means nothingness is likely to decay into a state of somethingness as time goes along. But this assumes both time and the background physical theory defining what it is that is unstable. So it suffers from the same problem.