“There’s no particular reason why our human brain should have evolved just far enough to be able to simulate the deepest levels of reality. What is amazing is that we have been able to make so much sense as we have of the external world. I believe when the history of science is written, then what has been discovered about our universe in the last decade or two will be one of the most exciting chapters. But the key question, of course, is: “What we still don’t know?” And that is the challenge for the coming century.”

— Sir Martin Rees, What We Still Don’t Know: “Are We Real?” (Channel 4 series, 2004)