Physics and equations

Paul Dirac: Professor of Mathematics at the University of Cambridge 

and discoverer of antimatter

What it means really to understand an equation — that is, in more than a strictly mathematical sense — was described by Dirac. He said: “I understand what an equation means if I have a way of figuring out the characteristics of its solution without actually solving it”. So if we have a way of knowing what should happen in given circumstances without actually solving the equations, then we “understand” the equations, as applied to these circumstances. A physical understanding is a completely unmathematical, imprecise, and inexact thing, but absolutely necessary for a physicist.

Richard Feynman [1918-1988, 1965 Nobel Prize in Physics]