So far as physics is concerned, time's arrow is a property of entropy alone.

Never accept a fact until it has been verified by theory.

The mathematics is not there till we put it there.

The understanding between a non-technical writer and his reader is that he shall talk more or less like a human being and not like an Act of Parliament. I take it that the aim of such books must be to convey exact thought in inexact language... he can never succeed without the co-operation of the reader.

The pursuit of truth in science transcends national boundaries. It takes us beyond hatred and anger and fear. It is the best of us.

Our ultimate analysis of space leads us not to a "here" and a "there," but to an extension such as that which relates "here" and "there." To put the conclusion rather crudely-space is not a lot of points close together; it is a lot of distances interlocked.

A hundred thousand million Stars make one Galaxy; A hundred thousand million Galaxies make one Universe. The figures may not be very trustworthy, but I think they give a correct impression.