The Oh-My-God particle

John Walker of Fourmilab Switzerland, founder of Autodesk and author of AutoCAD wrote in 1994 about the Oh-My-God particle – a proton that was detected travelling at only 1½ femtometres per second slower than the speed of light.


What I think is really interesting are the comparisons of distances and travel times: At that speed the particle would, after travelling for a light-year, lag only 46 nanometres behind a photon released at the same point and the same time. Indeed an observer tavelling along with this particle could travel from Earth to Alpha Centauri in 0.43 milliseconds, but even so it would take over 19 days to reach the edge of the universe.


This came up in a Slashdot discussion about the activation next year of the LHC at CERN. This collider is expected to create tiny black-holes as a result of high-energy collisions – and some commentators are voicing concerns about the possibility of one of these objects not evaporating (due to Hawking radiation) but instead absorbing the other particles in the accelerator and expanding uncontrollably. Whilst this is discounted by most physicists as being a very remote possibility, it should probably be borne in mind that the scientists working on the Manhatten Project weren’t entirely sure that an nuclear detonation wouldn’t ignite and burn off the atmosphere until after the first detonation…