“LHC, The Universe and Everything” was the title of a lecture giving an update on the Large Hadron Collider and CERN. Dr David Evans of Birmingham University outlined the physics behind the LHC in an entertaining and comprehensive, but adequately basic manner for this non-academic would be physicist.
He illustrated his talk with fascinating PowerPoint and gratuitous use of volunteers who followed his instructions to manipulate magnets and demonstrate particles moving through tubes representing the collider. Then he explained about the cooling process needed for these particles which are superheated to many times the temperature of the sun. They need to be cooled to lower than the temperature of outer space.
He used liquid nitrogen and rubber tubing to discuss the type of cooling needed. Rubber tubing inserted into liquid nitrogen becomes friable and can be smashed easily against a table - a great effect during a lecture. In reality, CERN supercools with superfluid hellium. Liquid nitrogen is safer in a lecture room.
After questions, dominated as per usual by volubly egotistical elderly blokes who appeared to be even more wannabe physicists than me, Dr Evans offered the audience a chance to play with the liquid nitrogen. Yippee! I love to experiment, so I moved toward the front to stand in line to get a polystyrene cup of liquid nitrogen to pour over my palm. In order not to give yourself a freezer burn, it is best to hold your palm at an angle so that the liquid nitrogen can slide off onto the floor where it evaporates harmlessly (without damage to the flooring). I tried this a few times, expecting to feel whatever it was that caused some hulking great brutes who’d pushed ahead of me to squeal. I felt nothing; maybe my hot little palms were too superheated to allow the liquid to get close enough to do more than give a faint tingle.
In a corner of the room, some opportunistic student types had drawn back the curtains to expose a broad window ledge where they were engaged in their own experiment: throwing small amounts of liquid nitrogen along the ledge to watch it fizzle, pop and evaporate. Some reminiscences were shared about antics in labs by those of us a little older, but clearly not wiser.
I was left with the consequences of my own inadvised playing with the cup of liquid nitrogen; I stuck my rather arthritic forefinger into it and, while, again feeling nothing, was left with a persistent ache for the next day, as the joint swelled a little as a result of the low temperature. This is a warning to myself to think before doing this again and to remember that extreme cold is the wrong environment for arthritis.
For more scientific discussion look up CERN.
http://public.web.cern.ch/public/en/spotlight/SpotlightCool-en.html
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