One of the chapters of my book about the way that we see our place in the universe (see the column on the right) is about the idea that the universe is essentially composed of nothing at all – despite its obvious solidity (in places at least). It’s about the way that nothing can give rise to something. The chapter is titled Nothing Matters (which is meant to be a pun by the way).
Here’s a very entertaining lecture by theoretical physicist Lawrence Krauss which deals nicely with aspects of this subject. (Should you only want to dip into the lecture briefly the most relevant quote is about 40 minutes in. Should you not want to dip in at all, the quote is, in truncated form, [The universe] has zero total energy, and it could have begun from nothing…which answers the question…’Why is there something rather than nothing?’.)