Helium balloons?

Have you seen helium balloons (the balloons that float)? Did you know that helium can be used for other things, as well? There is only a small amount of helium on the planet. We use helium in our experiments to measure things at low-temperatures. Liquid nitrogen can only cool things to around 77  K. Liquid helium, however, can cool things much more (to less than 0.2 K; 0 K is the lowest temperature and it is impossible to actually reach (this can be proven)). Some things are easier to measure at low-temperatures (or are impossible to measure at high temperatures). Save the helium!

Comic from Maki Naro