Liquid Nitrogen Avalanche

In physics lab today, we were doing experiments with superconductivity, and liquid nitrogen was involved. (Note that unlike my experiences in the summer of 2008, this was a special high temperature superconductor for which liquid nitrogen alone was cold enough). One of my lab partners had put his laptop computer on a desk surface near where I was working with liquid nitrogen, and had numerous times before expressed fear of his laptop getting droplets of liquid nitrogen in it, in case that would be bad for it.

Now, my two lab partners were busy looking at some circuitry, while I was pouring liquid nitrogen into a cup. I decided to move farther from the laptop, which turned out to be a good idea. Suddenly, the cup fell over and a flood of boiling liquid nitrogen, 77 Kelvin, came rampaging out of the cup, along the desk surface, and falling onto the carpeted floor in a loud fwooooooooooooooosshhhh! of vaporizing nitrogen. I said nothing, merely responding to the spill.

My lab partners did not look up from what they were doing, but clearly they heard the long, drawn-out liquid nitrogen avalanche. Eventually they began to laugh. "I hope a certain party is OK," one of them said, chuckling.

I looked over.

"Yes, and it was especially funny since you didn't say anything, but we heard it. I was just thinking No! My computer!"

"Luckily," I replied, laughing, "I thought to move away from your computer when I was doing this."

And so we returned to our work, which involved nothing less than levitating magnets and creating currents that go on in a ring-shaped sample "forever", as long as liquid nitrogen is always on it.

-Philip