When the poet Paul Valery once asked Albert Einstein if he kept a notebook to record his ideas, Einstein looked at him with mild but genuine surprise. "Oh, that's not necessary," he replied . "It's so seldom I have one.

For a long time it puzzled me how something so expensive, so leading edge, could be so useless. And then it occurred to me that a computer is a stupid machine with the ability to do incredibly smart things, while computer programmers are smart people with the ability to do incredibly stupid things. They are, in short, a perfect match.

Because time moves more slowly in Kid World ... it goes on for decades ... It is adult life that is over in a twinkling.

It is a slightly arresting notion that if you were to pick yourself apart with tweezers, one atom at a time, you would produce a mound of fine atomic dust, none of which had ever been alive but all of which had once been you.

I really enjoy going to a library and spending the day doing research - to me that is the most pleasurable part of writing the science book.

The universe is not only queerer than we suppose; it is queerer than we can suppose

In a funny way, nothing makes you feel more like a native of your own country than to live where nearly everyone is not.