What is life? It's not so much the question, how did life come about on our planet? That's a historical question. In order to find out how life originated on earth you have to have witnesses, and you have to... and since this time precedes the geological witnesses there is not much we can do. So the questions we can really answer is: how is it possible that something like life can come about? So in our case life is not the historical process which took place. Life is a principle. Life is some behaviour of matter and many people have asked that question: what type of behaviour of matter is it? What is life?

Well, first of all we see life now as being represented by the living beings, and there is a huge multiplicity of different living beings. And to subsume them under one word, namely the word 'life', wouldn't give you much information about what life really is. If you know everything about coli, what do we know about man? So we asked more the question: what are the principles? What has to be fulfilled? What has to come about? And we see it's not so much the structures you find there. Of course, I said life is formed on structures, therefore I am not a believer in simulation of life by computers. Why not? Because the computer only does what you program it for. In other words, if I want to program life in a computer, I must program the whole physics and chemistry in it. Because life takes care of those things, life makes... takes advantage of the structures being present. And if the computer will tell you about how really the systems that evolve look like, you must program that all into the... But you can do much more by doing experiments on it, or doing very directed experiments, to ask certain questions.

[Q] I call that 'if then' questions.

Yes.

[Q] If you have this random circumstance, these random conditions, then the system will behave...

That's all we can do in science, that's all we can do in physics too, given that... what follows from it. We can't ask for the principal causes, for the first causes, and I think the biggest mistakes which have been made were to ask such questions. Rather than to find out what really happens, what follows from what and what has to be fulfilled in order that something like that comes. So life to us appears to be a dynamical process. There's no evolution of single individuals. Evolution is the property of populations, so life as a whole thing evolves... up to humans.