As those who have seen Jurassic Park will know, this means a tiny disturbance in one place, can cause a major change in another. A butterfly flapping its wings can cause rain in Central Park, New York. The trouble is, it is not repeatable. The next time the butterfly flaps its wings, a host of other things will be different, which will also influence the weather. That is why weather forecasts are so unreliable.

I cannot give any scientist of any age better advice than this: the intensity of a conviction that a hypothesis is true has no bearing over whether it is true or not.

The great mathematician fully, almost ruthlessly, exploits the domain of permissible reasoning and skirts the impermissible. That his recklessness does not lead him into a morass of contradictions is a miracle in itself: certainly it is hard to believe that our reasoning power was brought, by Darwin's process of natural selection, to the perfection which it seems to possess.

It was unthinkable not long ago that a biologist or paleontologist would be at the same conference as an astrophysicist. Now we have accumulated so much data in each of these branches of science as it relates to origins that we have learned that no one discipline can answer questions of origins alone.

Indeed, the whole human species is endangered, by nuclear weapons or by other means of wholesale destruction which further advances in science are likely to produce.

As climate change moves from a model of the future to the reality of the present, health care systems across the country are facing a difficult set of questions. What are doctors supposed to do when wildfires, rising floodwater or other natural disasters threaten their ability to provide care for patients?