Physics is the science of the natural world, which deals with the fundamental particles the universe is made of, the interactions between them, and the interactions of objects composed of them (nuclei, atoms, molecules, etc).
- Physicists use the wave theory on Mondays, Wednesdays and Fridays and the particle theory on Tuesdays, Thursdays and Saturdays
- William Henry Bragg; quoted in Dictionary of Scientific Quotations by Alan L. Mackay, Institute of Physics Publishing, Bristol, 1994, p. 37 
- Variant: On Mondays, Wednesdays and Fridays we teach the wave theory and on Tuesday, Thursdays and Saturdays the corpuscular theory.
- Quoted in Physically Speaking: A Dictionary of Quotations on Physics and Astronomy by C.C. Gaither, 1997, ISBN 0750304707. 
- unsourced variant: God runs electromagnetics by wave theory on Monday, Wednesday, and Friday, and the Devil runs them by quantum theory on Tuesday, Thursday, and Saturday. 
- Physics and philosophy are at most a few thousand years old, but probably have lives of thousands of millions of years stretching away in front of them. They are only just beginning to get under way.
- Physics and Philosophy (1942), p.217.
- Our judge is not God or governments, but Nature.
- "If I were forced to sum up in one sentence what the Copenhagen interpretation says to me, it would be 'Shut up and calculate!'"
- All science is either physics or stamp collecting.
- Sir Ernest Rutherford
- Variant: In science there is only physics; all the rest is stamp collecting.
- Even if there is only one possible unified theory, it is just a set of rules and equations. What is it that breathes fire into the equations and makes a universe for them to describe?
- Guests at a cocktail party in the Southern Hemisphere tend to circulate in an anticlockwise direction.
- Corollary to Parkinson's 2nd Law
- I think I can safely say that nobody understands quantum mechanics.
- If [quantum theory] is correct, it signifies the end of physics as a science.
- My goal is simple. It is a complete understanding of the universe, why it is as it is and why it exists at all.
- Nothing is more interesting to the true theorist than a fact which directly contradicts a theory generally accepted up to that time, for this is his particular work.
- Physics is like sex. Sure, it may give some practical results, but that's not why we do it.
- The theory of quanta can be likened to medicine that cures the disease but kills the patient.
- The universe is an intelligence test.
- Toast always lands buttered-side down, and a cat always lands feet first. I propose we strap buttered toast to the back of a cat; the two will hover, spinning inches from the ground. With a giant buttered-toast/cat array, a hovering monorail could easily link New York with Chicago.