If your theory is found to be against the second law of thermodynamics I give you no hope; there is nothing for it but to collapse in deepest humiliation.

Every body continues in its state of rest or uniform motion in a straight line, except insofar as it doesn't.

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

[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.

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.

What is possible in the Cavendish Laboratory may not be too difficult in the sun.

Whatever else there may be in our nature, responsibility toward truth is one of its attributes.