Once again, my colleague Stephen Hawking has upset the apple cart. The event horizon surrounding a black hole was once though to be an imaginary sphere. But recent theories indicate that it may actually be physical, maybe even a sphere of fire. But I don't trust any of these calculations until we have a full-blown string theory calculation, since Einstein's theory by itself is incomplete.

The idea that excites me the most concerns the two greatest puzzles in science: the origin of the universe, and the origin of consciousness. The origin of the universe is what I do for a living, working on string theory. But I am also fascinated by consciousness.

We have learned more about the brain in the last fifteen years than in all prior human history, and the mind, once considered out of reach, is finally assuming center stage.

Our best shot at finding life in our solar system might be to look at the moons of Jupiter and Saturn. Mars, increasingly, looks like a dead planet. But the oceans beneath the ice cover of the moons of Jupiter and Saturn may actually have more liquid water than the oceans of Earth.

The strength and weakness of physicists is that we believe in what we can measure. And if we can't measure it, then we say it probably doesn't exist. And that closes us off to an enormous amount of phenomena that we may not be able to measure because they only happened once. For example, the Big Bang. ... That's one reason why they scoffed at higher dimensions for so many years. Now we realize that there's no alternative.

Srinivasa Ramanujan was the strangest man in all of mathematics, probably in the entire history of science. He has been compared to a bursting supernova, illuminating the darkest, most profound corners of mathematics, before being tragically struck down by tuberculosis at the age of 33, like Riemann before him. Working in total isolation from the main currents of his field, he was able to rederive 100 years' worth of Western mathematics on his own. The tragedy of his life is that much of his work was wasted rediscovering known mathematics.

What differentiates human from lower-animal consciousness is time. You can't explain the concept of "tomorrow" to your dog. Our consciousness is dominated by time - We're constantly running simulations of the future. Our brain is a prediction machine. The hallmark of intelligence, indeed of genius, is the number and complexity of the feedback loops we use in predicting the future.