Everybody's Heard About The Bird

Last week, after going to see DJ Dan play in Halifax, we were driving home when I saw a dead pheasant (frozen solid) in the road. Ian Allen was acting as my Transportation Engineer that night (ie. designated driver) and I told him that I had to have the pheasant. I took it home and hid it in the freezer at the house, so when my roommate Jamie opened the freezer, this dead bird would lunge out at him. He finally found it today, six days later.

But that’s not what I came here to tell you about. I came to talk about the draft. Oh wait, no, that’s a line from “Alice’s Restaurant,” by Arlo Guthrie.

In honor of the frozen pheasant in the freezer, today’s blog topic is about what happens to objects when they get really cold: specifically, what happens to them at absolute zero. So this is a physics-oriented post.

Now I knew that things stop moving around much as they get colder, and even gases will eventually freeze into a liquid form. As a liquid gets colder, the molecules move around less and less, and get closer together. The liquid will then turn into a solid as it gets extremely cold. So I was thinking about this, and trying to decide if that means that all motion stops at absolute zero. I wondered this because I figured that if this was actually the case, the object would shrink massively and become extremely dense. I had to do some digging and reading to figure this out.

I was under the impression that the molecules (or atoms) of a solid are effectively dense and “locked into place,” and stop moving as its gets colder. However, what about the electrons? An atom of a substance is the smallest individual unit possible of a chemical element. For convenience, we generally describe an atom being semi-analogous to a solar system, with the nucleus of the atom being like the sun, and electrons being like planets which are orbiting the sun. But if all motion stops at absolute zero, then the electrons would stop orbiting the nucleus and that obviously does not happen, because if it did, the atom would collapse and become extremely small, and would no longer exist as we know it. Or does it?

After a bit of reading, I learned that while an object does stop emitting radiation at absolute zero, its constituent parts don’t stop moving entirely. The energy and motion is certainly reduced, but the behavior of the object is explained by what is called zero-point motion. That’s a quantum physics theory, not classical physics, so I won’t get into that. But at least my curiosity was solved.

The pheasant certainly doesn’t appear to be moving, but it is interesting to know that even if it was frozen to absolute zero, its component substances would remain active on an atomic/sub-atomic level.