Question: What sort of effects do you see at what temperature?

Suzanne McEndoo answered on 18 Mar 2012:

Ooo, good question. There are lots of cool things, but I’ll tell you about the few I know best.

For starters, how low can temperature go? Temperature is a measure of how fast the atoms in something are moving and vibrating, so if everything stopped moving, then it would be the lowest temperature possible. We call this absolute zero, and it’s about -273.15 degrees below zero. We can never actually reach this temperature, but we get pretty close.

The types of temperatures I talk about in my work are about a billionth of a degree about absolute zero. This is much, much colder than outer space, which is actually about 3 degrees above absolute zero.

One of the things that can happen when things get this cold is that large number of atoms can start behaving like a huge single atom. If you think about the air in the room, all the atoms are whizzing around randomly, so kinda like people walking along a street, everyone is doing their own thing.

Below a certain special temperature, some atoms will start moving more like an army, so everyone is moving at the same speed, moving in time with each other. So you have a million atoms acting like a huge quantum object (it can be as big as a few micro metres across).

This army of atoms is called a Bose-Einstein condensate (I’m going to call it a BEC for short, because that’s kinda long). A BEC has lots of cool properties, like being a superfluid. Superfluids can do weird stuff, like flow up hill, or flow without friction (so it doesn’t slow down). If you make a whirlpool in a superfluid it keeps spinning even after you stop stirring it.

There are lots of other things you can do at these really cold temperatures, like make grids of “atom traps” where you can trap one atom in each grid space. Then you can kick some of the atoms out and draw pictures with single atoms.