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

It is also a good rule not to put overmuch confidence in the observational results that are put forward until they are confirmed by theory.

In the world of physics we watch a shadowgraph performance of the drama of familiar life. The shadow of my elbow rests on the shadow table as the shadow ink flows over the shadow paper. It is all symbolic, and as a symbol the physicist leaves it. ... The frank realisation that physical science is concerned with a world of shadows is one of the most significant of recent advances.

An electron is no more (and no less) hypothetical than a star. Nowadays we count electrons one by one in a Geiger counter, as we count the stars one by one on a photographic plate.

You cannot disturb the tiniest petal of a flower without the troubling of a distant star.

In any attempt to bridge the domains of experience belonging to the spiritual and physical sides of nature, time occupies the key position.

Observation and theory get on best when they are mixed together, both helping one another in the pursuit of truth. It is a good rule not to put overmuch confidence in a theory until it has been confirmed by observation. I hope I shall not shock the experimental physicists too much if I add that it is also a good rule not to put overmuch confidence in the observational results that are put forward until they have been confirmed by theory.