From The Washington Post:
In “The Hitchhiker's Guide to the Galaxy,” Douglas Adams famously had his characters ask a computer to provide the ultimate answer to “Life, the Universe, and Everything.” As Stephen Hawking and Leonard Mlodinow point out in their book “The Grand Design,” the computer's response — 42 — was less than helpful. Hawking, who needs no introduction, and Mlodinow, a Caltech physicist with a string of excellent books to his credit, have taken on that ultimate question in a somewhat more rigorous form by asking three related ones:
Why is there something instead of nothing?
Why do we exist?
Why does this particular set of laws govern our universe and not some other set?