1st Baron Rutherford of Nelson

An alleged scientific discovery has no merit unless it can be explained to a barmaid. As quoted in Einstein: The Man and His Achievement (1973) by G. J. Whitrow, p. 42
Variants:If you can't explain your physics to a barmaid it is probably not very good physics. As quoted in Journal of Advertising Research (March-April 1998)
A theory that you can't explain to a bartender is probably no damn good. As quoted in The Language of God (2006) by Francis Collins, p.60`~~~~Ernest Rutherford, 1st Baron Rutherford of Nelson