“The usual approach of science of constructing a mathematical model cannot answer the questions of why there should be a universe for the model to describe. Why does the universe go to all the bother of existing?”

“Even if there is only one possible unified theory, it is just a set of rules and equations. What is it that breathes fire into the equations and makes a universe for them to describe?”

“It is no good getting furious if you get stuck. What I do is keep thinking about the problem but work on something else. Sometimes it is years before I see the way forward. In the case of information loss and black holes, it was 29 years.”

“If we do discover a complete theory, it should be in time understandable in broad principle by everyone . . . . Then we shall all, philosophers, scientists, and just ordinary people be able to take part in the discussion of why we and the universe exist.”