Saturday, February 05, 2005

Physics Fantasia

I told Ken to find me something to blog about, and he told me I ought to share the glories of Falstad's physics applets with my readers.

Paul Falstead appears to be a California software developer with too much time on his hands. He's written little programs to help scientists visualize the systems that they frequently describe mathematically. Ken is such a nerd that he thinks this is really cool.

The only problem with showing these to a non-physics audience is that there is no explanation included with the applets. If you don't know what a wave function is, how are you supposed to appreciate the full beauty of the breathtakingly complex hyrodgen atom wavefunctions?

I suppose he left off the explanations because they're hard, but let me try, a little. A hydrogen atom is the simplest kind, a heavy, positively charged "proton" with an electron "orbitting" it. Most people have seen pictures that show something like a baseball going in a circle around something like a basketball, but the truth is, the electron is more like the ripple from a rock dropped in a pond, than it is like a baseball. It is a wave pattern, which we call a wavefunction because we're usually describing the pattern mathematically, rather than looking at pictures of it. If I shine light on the atom, I can distort the pattern... The applet shows all of the different patterns I can have, all of the intricate, stunning shapes. Here are the things you should try. First, select "complex orbitals" from the top drop down menu. Go to a high "n" -- like 14. Then give it a big "l" -- like 11. Now look at the different "m" values... Zero and 3 and 4 are pretty cool, but so are some of the less symmetrical shapes you get at the higher numbers. Make sure to turn the resolution up. Now click and hold on the image to drag it around and look at it from different angles. Try turning up the simulation speed or stopping it. Now try to remember, as you're doing this, that these are probably the most accurate depictions of real atoms that you've ever seen. That these shapes occur in nature. That you yourself are nothing but the sum of seven billion billion billion overlapping, ghostly clouds, just like this.

Try making less symmetrical patterns by choosing "complex combos" off of the top drop down menu, and then picking two or three of the circles which appear at the bottom of the picture. (Make sure you have the simulation speed somewhere in the middle of the slider, and don't have it stopped.) Try clicking on the top left circle from each block of circles, and then click on the image again and drag it around. Clear it, and try other combinations. Hypnotic, isn't it? These are real too.

Now try going back to the main page and picking the atomic dipole transitions applet. This shows an animated picture of how light transforms one of these patterns into another. This is what we study all day. These are the pictures in our minds, as we try to provoke atoms into moving and glowing and interacting in the ways we want. Sometimes we even have a specific shape in mind, a specific wavefunction, that we try to prod the atoms into with lasers beams and magnetic fields, vaccuum chambers and heating coils and cavities. When I look at these pictures, I love my job.

There's a lot more there -- the vector field and Fresnel diffraction toys are especially fun to play with if you know what you're looking at... Only I am not up to the challenge of explaining those right now, without using math.

But they're gorgeous, aren't they? Perhaps later I'll attempt to write a poem about them, like the ones Andrew discovered by James Clerk Maxwell... (Or maybe I'll just post that one, as next month's poetry post.)

Physics is beautiful.

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