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

Schrödinger's wave-mechanics is not a physical theory, but a dodge - and a very good dodge too.

The universe will finally become a ball of radiation, becoming more and more rarified and passing into longer and longer wave-lengths. The longest waves of radiation are Hertzian waves of the kind used in broadcasting. About every 1500 million years this ball of radio waves will double in diameter; and it will go on expanding in geometrical progression for ever. Perhaps then I may describe the end of the physical world as-one stupendous broadcast.

I don't believe any experiment until it is confirmed by theory. I find this is a witty inversion of "conventional" wisdom.

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

[When thinking about the new relativity and quantum theories] I have felt a homesickness for the paths of physical science where there are ore or less discernible handrails to keep us from the worst morasses of foolishness.

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.