I’m the kind of person who would get annoyed if they saw this blog because there’s no closure. What happened to this guy who made two posts in 2013? So for anybody who somehow stumbles across this page, here’s the answer.
I’m more than halfway to my physics Ph.D. on cold atoms, the same field as the experiment in the “below absolute zero” post. Still don’t know what to do afterwards, but I’ll figure something out.
Thanks for visiting my site.
Here’s my skin-deep understanding of the negative Kelvin temperatures mentioned in this article.
Rod of length 
and mass 
swinging about a pivot. First time using Inkscape, so I went and added 
, too.
I came across a slightly more advanced variation of this problem in a mechanics course earlier last semester, and for some reason I just couldn’t figure out how to find the kinetic energy. I found it instructive to go through a quick calculation…