I don’t make any claims to answer any questions that science cannot answer, and I have tried very carefully within the text to define what I mean by … - Lawrence M. Krauss

Whenever one asks “Why?” in science, one actually means “How?”. “Why?” is not really a sensible question in science because it usually implies purpose and, as anyone who has been the parent of a small child knows, one can keep on asking “Why?” forever, no matter what the answer to the previous question. Ultimately, the only way to end the conversation seems to be to say “Because!

the universe is big and old and, as a result, rare events happen all the time. Go out some night into the woods or desert where you can see stars and hold up your hand to the sky, making a tiny circle between your thumb and forefinger about the size of a dime. Hold it up to a dark patch of the sky where there are no visible stars. In that dark patch, with a large enough telescope of the type we now have in service today, you could discern perhaps 100,000 galaxies, each containing billions of stars. Since supernovae explode once per hundred years per, with 100,000 galaxies in view, you should expect to see, on average, about three stars explode on a given night.

If you have nothing in quantum mechanics, you will always have something.