I have lived with the prospect of an early death for the last 49 years. I'm not afraid of death, but I'm in no hurry to die. I have so much I want to do first. I regard the brain as a computer which will stop working when its components fail. There is no heaven or afterlife for broken down computers; that is a fairy story for people afraid of the dark.

In real time, the universe has a beginning and an end at singularities that form a boundary to space-time and at which the laws of science break down.

The human race shouldn't have all its eggs in one basket, or on one planet. Let's hope we can avoid dropping the basket until we have spread the load.

Gravity is so strong that space is bent round onto itself, making it rather like the surface of the earth. If one keeps traveling in a certain direction on the surface of the earth, one never comes up against an impassable barrier or falls over the edge, but eventually comes back to where one started.

Government works best under the glare of public scrutiny. Absent such scrutiny, abuses occur.

Do you ever wonder how much deeper the ocean would be without sponges?

I thought Eddie Redmayne portrayed me very well... At times I thought he was me.