Cool Science

Helium is a tricky thing - it's a very light, monatomic gas, which is exceedingly unreactive (inert). With a great deal of effort you can cool liquid helium to about -269^o Celsius and it will finally liquify at this temperature. It's pretty tedious to call this -269 degrees Celsius, and it's kind of hard to wrap your brain around a temperature that cold, so to put this on the Kelvin absolute temperature scale that is the same as 4 K. Helium is one of nature's most amazing gifts to scientists. And of course, like any precious resource, we're using it up. Helium is so light it escapes eventually to space. What's it good for?

Magnets of course - really, really, big magnets. Some conductors, when cooled to very low temperatures (like 4 K) become superconductors. They transmit current without resistance. So a terrific way to make a magnet is to make a coil of this wire, immerse the wire in liquid helium, and then put some current in the wire. The current will persist indefinitely and the magnetic field that results from the electric current flowing through the coil will also persist indefinitely. It's a magnet you don't have to plug in! These are the kinds of magnets used in magnetic resonance imaging, for example, and a lot of other important things too.

Political aside : I know nobody reads this and it's just my own journal, but I'll make a suggestion for some political action anyway. Helium is a big part of the foundation on which most modern research has been built. It doesn't always get a lot of time in the spotlight, but if it ever goes away we're in big trouble. If you find yourself writing your congressional rep, please consider putting in a word for Helium as a precious resource in the nation's interest that we should be stockpiling, and finding new sources for mining, etc.