"There are two great mysteries that overshadow all other mysteries in science. One is the origin of the universe. That’s my day job. However, there is also the other great mystery of inner space. And that is what sits on your shoulders, which believe it or not, is the most complex object in the known universe. But the brain only uses 20 watts of power. It would require a nuclear power plant to energise a computer the size of a city block to mimic your brain, and your brain does it with just 20 watts. So if someone calls you a dim bulb, that’s a compliment."