Paul Davies

Astonishingly, in spite of decades of research, there is no agreed theory of cancer, no explanation for why, inside almost all healthy cells, there lurks a highly efficient cancer subroutine that can be activated by a variety of agents - radiation, chemicals, inflammation and infection.

A permanent base on Mars would have a number of advantages beyond being a bonanza for planetary science and geology. If, as some evidence suggests, exotic micro-organisms have arisen independently of terrestrial life, studying them could revolutionise biology, medicine and biotechnology.

To ask questions can become the laziest and wobbliest occupation of a mind, but when you must yourself answer the problem that you have posed, you will meditate your question with care and frame it with precision.

Every time I see documentaries or infomercials about little kids with cancer, I just freak out. It affects me on the highest emotional level... Anytime I think about it, it makes me sadder than anything I can think of.