But what is more interesting than what it forbids is what quantum theory permits. It permits particles to pop into existence spontaneously, if briefly, out of a vacuum. This scenario of creation ex nihilo led quantum cosmologists to entertain an arresting possibility: that the universe itself, through the laws of quantum mechanics, bounded into existence out of nothing. The reason there is Something rather than Nothing is, as they fancifully put it, that nothingness is unstable.
