"Everything that begins to exist..."

If you travel (or read) in atheist (or apologetic) circles, then you've probably encountered the Kalam Cosmological Argument. It goes something like this:

1. Whatever begins to exist has a cause.
2. The Universe began to exist.
3. Therefore, the Universe had a cause.

Although it is historically linked to Islamic scholarship, it's most ardent proponent and popularizer is Christian apologist (and amateur Scott Bakula impersonator) William Lane Craig, who holds it up as unassailable proof of a Prime Mover.

This argument was brought to my attention again when I listened to a debate between Justin Shieber (one of the hosts of Reasonable Doubts, my favourite counter-apologetics podcast) and Scott Smith. Smith brought up this argument, and it was discussed briefly. Kalam is rife with problems, among them the compositional fallacy, one or more potentially unsupportable premises, and what amounts to special pleading. If you want a detailed deconstruction, I'd recommend the deconstructions of the argument on RationalWiki and Iron Chariots (we even covered it briefly on Life, the Universe & Everything Else). But as I listened to the debate, I got to thinking...

What does it mean for something to "begin to exist"?

As I thought about that some more, I got to wondering: Does anything "begin to exist", when it comes right down to it? I mean, at the level of common usage, things "come into being" all the time, from trains to mountains to people. But none of these things are created ex nihilo: they're merely examples of stuff (train parts, rocks, cells, molecules, subatomic particles) moving about. So while it makes sense to talk about these things "beginning to exist" in some sense (as we talk of the sun "rising and setting", for example), in the strictest sense I'm not sure.

I asked a physicist friend friend about this. He thought for a moment, chuckled, and said, "Maybe a photon? But not really..." And he couldn't come up with anything either. So this is something that I'm honestly wondering: Do we know of anything that can meaningfully be said to have "begun" to exist, rather than being simply an example of matter or energy changing form? Because if not, that's another significant blow to the argument. What do you think?

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Addendum: On the Facebook thread, my friend Javier Hernandez has pointed out that virtual particles and perhaps even space itself may qualify as "beginning to exist":

How about the "creation" of space in our Universe. The Universe is expanding, which means that more Vacuum is being created. There does not appear to be a Energy-to-Vacuum conservation law that is being followed, so this Vacuum appears to be "coming into existence" on it's own.

I find the idea of space itself "coming into being" tough to wrestle with, since this expansion of "space" is hard to quantify in discrete units, and it's a process that is continuous, rather than instantaneous. That said, both virtual particles and perhaps space itself seem to be fair candidates for what I was looking for here. Thanks to Javier for that!

This in mind, however, neither space nor virtual particles would seem to be "caused" in the strict sense implied by Kalam, so among the examples we've been able to identify, the argument remains incredibly weak on that particular score.