I was holding [my four-year-old daughter] and I said, 'Sophia, I love you more than anything in the universe.' And she turned to me and said, 'Daddy, universe or multiverse?'

A unified theory would put us at the doorstep of a vast universe of things that we could finally explore with precision.

When kids look up to great scientists the way they do to great musicians and actors, civilization will jump to the next level

When I give this talk to a physics audience, I remove the quotes from my 'Theorem'.

That is, you can have nothingness, absolute nothingness for maybe a tiny fraction of a second, if a second can be defined in that arena, but then it falls apart into a something and an anti-something. And that something is then what we call the universe. But can we really understand that or put rigorous mathematics or testable experiments against that? Not yet. So one of the big holy grail of physics is to understand why there is something rather than nothing.

Sometimes nature guards her secrets with the unbreakable grip of physical law. Sometimes the true nature of reality beckons from just beyond the horizon.

Most scientists like to operate in the context of economy. If you don't need an explanatory principle, don't invoke it.