How meaningful could the comparison between the, for lack of a better word, existential void, and the physical void from which matter is spontaneously generated, as understood by mainstream physics?
Zizek seems happy to suggest that these are two "versions" of the same thing, although he would introduce language to complicate their relationship.
William Lane Craig points out, though - not in response to Zizek but generally - that the quantum-cosmic void is really not a nothingness at all. The whole point, in fact, it that it is swarming with energy (the Higgs boson etc)
Of course, so is the existential void...