my work

Some people have been asking about my job. I think this is flattering but maybe they don't know how long I can talk about it. I will try to keep it short and not go on tangents.

Here is my machine.

It looks like my old machine but smaller. In some ways it is a lot more sophisticated, mostly because I didn't build it! It's a vacuum chamber with a jet source on one end. The source is called a jet because when molecules spray out, they get accelerated to supersonic speed.

The middle of the chamber has this glass chip in it. The chip has electrodes all along it in a little stripe pattern. When we put a charge on the electrodes, little traps form for the molecules. Molecules get stuck hovering 20 microns above the chip and sit there.

What we want to do is image the molecules one by one using a camera. This sounds impossible, but it's really quite simple--at least in principle! The way we plan to do it is to use a laser to make the molecules absorb energy. The molecule would rather give up that energy, so it spits the light back out. We just wait until after the laser fires, then turn on our camera!

So why do it? My boss says, "I don't know what it's good for, but it's fun." But I think there is a lot of potential for this kind of work. You never know when something will come in handy. When the guys built the first laser in the 60s everyone thought is was nice, but a little unnecessary. A curiosity. Now you can use it to get your eye fixed or that ugly tattoo removed.

I think trapped molecules on a chip can make a quantum-mechanical computer, or measure whether the fundamental constants of the universe change with time, or help people understand general relativity. We are just laying the groundwork now, figuring out the more mundane stuff before people can make the really exciting things work. That's what I hope anyway. We will see.

But in the meanwhile the whole thing is a bit of a kludge. See what I mean? These are how we make a magnetic field:

Bike wheels! They are wrapped in wire. When charged particles go in a circle, they make a magnetic field that points out of the circle's plane. Instead of a bike wheel, imagine a clock. When a positive charge goes clockwise the field points into the clock face. Why not out of the clock? This is one of the mysteries of nature.

Speaking of mysteries of nature, did you know that no one has ever found a magnetic monopole? On the surface this seems like a tedious thing to bring up, but I think it's fascinating. Here's why.

Electric charges moving in a circle make magnetic fields. These fields always have crazy shapes. The simplest shape anyone has ever seen is a dipole, like the field of the bike wheel. It points out of the clock face if you sit in the middle of the ring, but it reverses direction when you go outside the ring. Why no monopole fields? These are fields that point outward from the center, like a pincushion. Electricity has monopoles. Gravity has monopoles. Even nuclear forces have monopoles. Only magnetism doesn't.

But, it gets weirder.

It turns out that only one magnetic monopole, anywhere in the universe, forces all the electric charges to come in neat little integer bundles. Turns out they do come in integer bundles--multiples of e, the electron's charge. And that totally strange, totally implausible fact about electricity is exactly what experiments tell us. So, is there one magnetic monopole somewhere out there, quietly quantizing all our electric charges? No one knows. I hope there is. I hope it's in our house.