Physics is really figuring out how to discover new things that are counterintuitive, like quantum mechanics. It's really counterintuitive.

The lessons of history would suggest that civilisations move in cycles. You can track that back quite far - the Babylonians, the Sumerians, followed by the Egyptians, the Romans, China. We're obviously in a very upward cycle right now and hopefully that remains the case. But it may not.

If anyone thinks they'd rather be in a different part of history, they're probably not a very good student of history. Life sucked in the old days. People knew very little, and you were likely to die at a young age of some horrible disease. You'd probably have no teeth by now. It would be particularly awful if you were a woman.

It's important that we attempt to extend life beyond Earth now. It is the first time in the four billion-year history of Earth that it's been possible, and that window could be open for a long time - hopefully it is - or it could be open for a short time. We should err on the side of caution and do something now.

Even if producing CO2 was good for the environment, given that we're going to run out of hydrocarbons, we need to find some sustainable means of operating.

I think life on Earth must be about more than just solving problems... It's got to be something inspiring, even if it is vicarious.

I always had an existential crisis, trying to figure out ‘what does it all mean?’ I came to the conclusion that if we can advance the knowledge of the world, if we can expand the scope and scale of consciousness, then, we’re better able to ask the right questions and become more enlightened. That’s the only way to move forward.