Tuesday, October 20, 2009

Physics by the seat of the pants

I've long considered myself a 'seat of the pants' physicist, and have tried explaining the concept to a number of people. One way of putting it is to say I'm a 'first-order' sort of person. But that's not quite it. Another is to say that I have 'a feeling' for the physics, but that sounds like a pile of new-age bollocks. It's just that - sometimes - I know what the answer will be before I've worked it out. So, unless I have to, I don't bother working it out rigourously.

Today I came across these words of Feynman, who (of course) put it far more eloquently than my amateurish attempts:

"Mathematicians, or people who have very mathematical minds, are often led astray when 'studying' physics because they lose sight of the physics. They say "Look, these differential equations - the Maxwell Equations - are all there is to electrodynamics; it is admitted by the physicists that there is nothing which is not contained in the equations. The equations are complicated, but after all they are only mathematical equations and if I understand them mathematically inside out, I will understand physics inside out." Only it doesn't work that way.

What it means to really 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, 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."

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