A while back, Sixty Symbols asked a bunch of physicists what they thought would happen if you were to place your hand in the particle beam at the LHC and... none of them knew. Now they've done some digging, and found out.
As it turns out, the LHC's beam is focussed down to a tiny spot, less than 1 millimeter across. Also, it contains as much energy as an aircraft transporter in motion.
So, responses range from "I certainly wouldn't advise doing that" to "It's gonna burn right through you" and "It would hurt a lot". But really, I can't do justice to a bunch of incredibly intelligent physicists talking about shoving a hand in front of the world's most expensive experiment. You'll just have to watch it yourself. [Sixty Symbols via The Guardian]