7.17.2009

More cold in more places

I spotted some structure amongst all the scientific snarl.

The bottom parts are cylindrical to fit in a dewar. The rig hangs from a big disk which covers the top of the dewar and the air is pumped out. Vacuums are used in cryogenics because no heat can conduct or convect (technically some heat does make it) through space (but there is radiation) when there isn't any air so it's much easier to get and keep stuff really cold.

I don't know in particular what most of these are for, but the rightmost one with three cylinders is used to calibrate thermometers. A certain gas works best for a certain temperature range so using three gives the instrument a wide range of reliability.