I'm going to grant Dr. Craig that if indeed the objection means to define "nothing" in the same terms as he does, it's a nonsensical objection. Absolute nothingness, which I like to call "Nothing" with a capital "N", is indeed devoid of any properties whatsoever; that's the whole point! The question, then, is whether the objector, whoever s/he was, meant Nothing in that sense, or "nothing" in the sense used by physicists like Alexander Vilenkin, Stephen Hawking and Lawrence Krauss – empty space, or even the absence of space itself. Craig does not say.
Nonetheless, Craig missteps on a couple of points.
To say that the universe was caused by nothing is to say that the universe had no cause.Craig makes this mistake often – interchanging the terms "without a cause" and "coming from nothing". But they are not the same thing. Not only do we have an example of virtual particles emerging from "something" (a quantum vacuum) without a cause, but Alexander Vilenkin, in describing a quantum-tunneling model of the past boundary of the universe, has this to say in his book Many Worlds in One:
If there was nothing before the universe popped out, then what could have caused the tunneling? Remarkably, the answer is that no cause is required. In classical physics, causality dictates what happens from one moment to the next, but in quantum mechanics the behavior of physical objects is inherently unpredictable and some quantum processes have no cause at all.Craig's foray into a passage from Plato's Timaeus fails as well. Imagine ancient times, when humans thought the Earth was flat. There were two possibilities: that the Earth went on forever, or that it had a boundary or "edge". But we now know there was a third possibility – that the surface of the Earth is finite, but has no boundary or edge. Similarly, a picture of the universe in classical physics gives us two possibilities – the observable universe is past-eternal, or it has a beginning. But quantum mechanics reveals a new possibility: that the universe is finite, but has no boundary – much like the surface of the Earth.
This is precisely what Stephen Hawking and John Hartle describe in their "No Boundary Proposal". We know that, at least in the formulation of General Relativity, the universe has a past boundary at the Big Bang – the so-called "cosmic singularity". We know the observable universe could not have gone infinitely into the past, though it could be part of a cycle of infinite expansion and contraction . The "boundary" could be merely an artifact of our limited understanding, and a quantum theory of gravity will erase it. It's also possible, along the lines of the model proposed by Borde, Guth and Vilenkin, that the boundary is a "closed spacelike hypersurface" that is spaceless and timeless, springing the universe into existence uncaused.
We do not know, of course. What we do know is that Plato didn't know anything about quantum mechanics or cosmology, and we ought to be mindful of that fact when considering the relevance of his existential musings.
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