A New World
My ramblings about science….

The following is based on a conversation with a friend on IRC earlier…

So what is handwaving? We often hear people describe something as handwaving…

So here’s my take on what a handwaving argument is:

There’s no real evidence or scientific rigour shown you just say “well it kinda works like this” and say something that sounds ligitimate but without every saying why it is legitimate, or really explaining anything.

I’ll explain this with a quick example, the Magneto-Optical Kerr Effect, is a change in the polarisation state of light incident on a magnetised sample. It’s a purely quantum mechanical effect relying on the exchange interaction, but a handwaving argument of how it works is:

The incident photon comes in and is absorbed by an electron, because the field of the photon is oscillating the electron oscillates, but as it’s magnetised and a moving charge there is a lorentz force applied to the electron:

So this changes the oscillation direction, so when the photon reemits the photon the oscillation direction has changed and therefore the polarisation state is different.

Everything I’ve said is wrong, it’s a classical interpretation that cannot be applied, and yet it sounds perfectly fine! Now the thing you didn’t see is that when I explain this to people I wave my hands around to give some idea, implying a physical reality that just isn’t true…
So why do we do this? Simply Because it can turn REALLY complicated things into just some bloke waving his hands about…

This entry was posted on Sunday, March 23rd, 2008 at 1:17 am and is filed under Quantum Mechanics, Research, classical physics. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.