Why is there something rather than nothing?
This is, supposedly, the "big question" of religion, metaphysics, and philosophy. But it's a stupid question: at some point everyone, theist and atheist alike, has to say, something just is. Whether it's God or the laws of physics and the initial conditions of the universe, something just is. The "big question" is not: why is there something rather than nothing? but: what are the characteristics and properties of the something that just is?
In the 18th century, when the philosophies of deism and atheism began to take hold (especially with David Hume (1711 - 1776)) one proposed something-that-just-is was the whole natural universe, which (barring a few anomalies) appeared to be more-or-less stable and eternal. The whole universe (comprising at the time the solar system and the nearby stars visible to simple telescopes), complex as it was, was considered by atheists to be simpler than the alternative theistic something-that-just-is of an interventionist creator deity. But the whole universe is still extremely complex, especially when we include human beings and all of Earth's varied life forms. There was some appeal to the compromise position of deism: a deity has to get the complex universe started; the operation of non-teleological natural law is sufficient to explain and understand everything that happens afterward. The creator endows human beings with reason (and perhaps a moral sense), but after that it's up to us to work out what we do with it.
As we investigated these natural laws with increasing sophistication, we discovered quite a lot of the apparent complexity of the universe emerged from a much simpler basis. With the nebular hypothesis, the something-that-just-is no longer includes each planet in its particular orbit, but just a diffuse nebula. With the theory of evolution, the something-that-just-is no longer includes hippopotamuses, giraffes, gorillas and human beings, just the simplest possible life form. And with modern physics, cosmology, chemistry, etc. we got the natural story of the something-that-just-is down to the Standard Model of the laws of physics and the initial conditions of the Big Bang (with some quantum randomness thrown in to mix things up a bit).
It bears repeating: even if the simplest natural something-that-just-is were the present-day physical universe in all the complexity modern observational methods have revealed, that model would still be better than the deistic model and incomparably better than the theistic magical creator deity who not only magically pops the whole thing into existence but magically (but undetectably) dabbles and adjusts affairs from time to time and who has an obsessive concern with what we do with our genitals and requires his spokesmodels to wear silly hats. But the natural something-that-just-is isn't so complex as the whole physical universe; it's eight skitty zillion times less complicated. A handful of laws, a couple of dozen parameters, some mass-energy, a few microscopic irregularities in the initial distribution and Bang! the whole physical universe follows. If the whole thing is better than theism, this dramatically reduced version relegates theism to the outskirts of the peanut gallery.
Supposedly, Stephen Hawking's new book — which I haven't read yet, as it hasn't been released — simplifies the natural something-that-just-is even more. Even the Standard Model (somehow) emerges from just gravity. Some people wanted to believe that we needed a creator deity to fiddle with a score of dials to get this universe; Hawking now claims — as I understand it — if we want a creator deity, His only job is to push one button, a job for which the nervous system of a fruit fly is vastly overqualified.
The theistic story of something-that-just-is was made absurd in Ancient Greece, when we first realized that the physical world operated according to mechanical, non-teleological laws. Once we don't need a god to make the wind blow, to make the Nile flood every year, and to sustain the process of life from moment to moment, we don't need a god, period. The entire debate since then has been the retreat of the parasitical priests and prophets from their positions of power and privilege (hooray for alliteration!), a retreat where these bastards have extracted blood, death and suffering for every inch of ground they've lost.
But they have indeed lost.