Keep Your Hands Inside The Ride at All Times

Not just a good idea; it's the law!

The Large Hadron Collider at the European Organization for Nuclear Reseach (CERN) uses a beam of protons to investigate the most basic nature of the universe.  It does this by accelerating the protons to a speed of 0.999999991c; that is 99.9999991% of the speed of light.

Courtesy of CERN

So the people at Sixty Symbols [I highly encourage visits to this site!] asked scientists what would happen if one were to stick a hand into the proton beam.

Here's the video: