Because there is a law such as gravity, the Universe can and will create itself from nothing. Spontaneous creation is the reason there is something rather than nothing, why the Universe exists, why we exist. … It is not necessary to invoke God to light the blue touch paper and set the Universe going.According to Stephen Hawking's theory, the universe as we know it can develop from the cosmological equivalent of an empty string. (Actually, I'm not so sure about that. His theory might involve the universe developing from zero, which requires even more to be defined.) Zero is not the same as undefined. If a physicist says he has evidence the universe started from zero, the question of how the zero was created is not meaningless.
I'm reminded of a famous anecdote about teaching statistics:
One of my college professors liked to ask his classes, “What is the difference between zero and nothing?” After allowing the students several minutes of metaphysical and sophomoric discussion he would write “0” and say, “That's zero.” Then, with a flourish he would erase the zero explaining, “And that's nothing.”To a physicist, the differences between undefined, nothing, and zero might seem like quibbling. To a mathematician or a computer programmer, it's not.
Digression: The theory, by the way, is still speculative. If I recall correctly, the “no-boundary” condition requires a finite universe and it is currently unknown if the universe is finite or infinite. On the other hand, that really is just quibbling.
To return to the creation question: Some people have been claiming that it makes sense to assume this universe is a simulation running in a larger universe. I'd like to see a debate between those people and Stephen Hawking.