Friday, February 5, 2010

Let's get right to the point.

I hate physics because I can't do it anymore. Once I could, or thought I could. Now I can't.

I can still do this and that, but when it comes down to it I don't really know what I'm doing. And that bothers me. Because I think I ought to know what I'm doing.

When I used to be able to do physics, it was because I made up my own rules. All you had to do was point me in the direction of the problem and I'd sit down figure out what was going on. It had to make sense, and in the end it always did. It seemed like I could do anything.

I remember in first year physics we had a lab on the Helmholtz resonator. You blow across the top of a beer bottle and you get a sound out of it. We had to do some measurements and plot the frequency against the volume of air in the bottle. They had a formula for us and it was no big deal. But I didn't want to look at the formula. I remember I went for a walk one night and just thought about it. I thought about it until I figured out what was going on, and then I came up with my own way to calculate the frequency. Oh, I might have been out by a factor of 2 or so, but I had an angle on the problem and I could work it out. I didn't need anyone to rely on a formula from the textbook. And if my calculation was partly wrong, there was at least a reason why it was wrong; and I could understand what the reason was.

Of course there were things I couldn't do. There is a calculation done by Maxwell in the 1870's where he took molecules of air in an enclosure, gave them a certain amount of total energy, and then calculated what percentage of them would have a given velocity: in other words, the whole statistical distribution. And I couldn't do it. But it didn't really matter, because I could still see what was going on. You have two molecules and when they glance off each other, there is an exchange which conserves energy and momentum, but the individual energies get re-arranged. And after a long enough time there would be a statistical equilibrium where the velocities and energies, no matter how they had started out, would be mixed up into a stable unchanging state. And that made sense, even if I didn't have the mathematical tricks to actually calculate the distribution. So I felt alright about it.

I don't feel alright anymore, and it's quantum mechanics that's to blame.

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