However, we will not establish self-sustaining colonies in space for at least the next hundred years, so we have to be very careful in this period. Most of the threats we face come from the progress we’ve made in science and technology. We are not going to stop making progress, or reverse it, so we must recognise the dangers and control them. I’m an optimist, and I believe we can.
The laws of physics say that new energy can’t be created, but something must have created the universe’s energy. Can we call it God? — Basil Philipsz
The positive energy of matter exactly balances its negative gravitational energy. So universes can be created for free, without violation of the law of conservation of energy. I’m not sure what this has to say about God, but it’s an idea with a lot of creative potential.
If you were a Time Lord, what moment in time would interest you, and why? —John Brookmyre
I would like to meet Galileo, the first modern scientist. He pointed out that simple observations, such as dropping weights from a height, show that things do not work in the way that Aristotle said they do. This must have been realised by many people, who put it down to imperfect observations, or other reasons.
But Galileo said the ancients were wrong, and started to work out the correct laws from the observations. That makes him the father
of modern science. I was born exactly 300 years after the death of Galileo, I hold the same job at Cambridge as Newton did, and I work on Einstein’s general theory of relativity.
Of the three, I feel closest to Galileo. He followed his nose, and was a bit of a rebel.
If you had to offer a piece of advice to future of scientists, what would it be? — Tara Struthers
Be curious, and try to make sense of what you see. We live in a universe governed by rational laws that we can discover and understand. Despite recent triumphs, there are many new and deep mysteries that remain for you to solve. And keep a sense of wonder about our vast and complex universe, and what makes it exist.
But you also must remember that science and technology are changing our world dramatically, so it’s important to ensure that these changes are heading in the right directions. In a democratic society, this means that everyone needs to have a basic understanding of science, to make informed decisions about the future.
So communicate plainly what you’re trying to do in science, and who knows, you might even end up understanding it yourself.
Stephen Hawking is delivering this year’s Reith Lectures, starting on Tuesday morning at 9:00 am on Radio 4 FM