By Anupum Pant
Reaching temperatures really cold, at the point where Nitrogen is a liquid is relatively simple. Just use the liquid Nitrogen you have stored in a nice insulated container. Like that, you could attain temperatures of about 77K (or about -196 degrees centigrade). Going cooler is also simple, use liquid Helium (or about -269 degrees centigrade). Now you’ll reach 4K.
But what if you need to go colder than that? A few experiments like one that measures the extremely tiny change in dimensions of a metal ball due to the gravitational waves needs temperatures like these. That’s because these extremely tiny changes due to the gravitation waves have to be larger than the movement of atoms in the metal ball itself. And this happens at very low temperatures (in the range of millikelvins). So how do we reach temperatures like those? Dr. Morello explains.