My professor for the physics class I've been taking all Summer, Dr. Turner, taught my dad back in the day. They're actually good friends (my dad did some research and some other stuff with him, etc.), and I didn't even know it when I signed up for the class. Before class at the second week or so he came up to me and knew my name without me even introducing myself- I had sent him an email before the class started, and he recognized the last name. He was on the lookout for me, and figured out who I was based on my similarities to my dad. I told my dad and that pretty much made his day.
Every other lecture he has experiments to show us, which are usually pretty cool. Most of the stuff today dealt with magnetism and electric current. They're always neat, but one of the cooler ones (no pun intended) today demonstrated what happens when a magnet is near a superconductor. The superconductor needs to be very cold to work, and liquid nitrogen fits the job perfectly. At 77 Kelvin (about-200 C or -320 F), there's no way you can accurately describe how freaking cold that is in terms we can easily grasp. I'll stop here, just short of a CSI-style pun.
Above a superconductor, a magnet will levitate, and will be surprisingly stable.
You can even spin it along the magnetic axis and it will go for a while since air resistance is the main thing slowing it down.
At the end of class, Dr. Turner decided to put some of the remaining liquid nitrogen to good use:
"There should be a law against wasting perfectly good liquid nitrogen."
