
Re: This Week's Finds in Mathematical Physics (Week 227)
Posted:
Mar 18, 2006 10:52 PM


In article <gerry17370D.09372316032006@sunb.ocs.mq.edu.au>, Gerry Myerson <gerry@maths.mq.edi.ai.i2u4email> wrote:
> John Baez wrote:
>> An EeV is an "exaelectronvolt", which is the energy an electron picks up >> going through a potential of 10^18 volts. 300 Eev is about 50 joules  >> the energy of a onekilogram mass moving at 10 meters/second, presumably >> all packed into one particle! Nobody knows how such high energies are >> attained 
>How fast does, say, a proton have to be going to have that much energy?
It's sort of tiresome figuring out the right number of nines, so I won't bother with the precise figure, but it's something like .999999... times the speed of light. Fast.
Too vague for you?
The massenergy of a proton is very roughly 1000 MeV. This particular proton had an energy of 300 EeV. So, find the velocity v, as a fraction of the speed of light, such that
300 EeV / 1000 MeV = 1/sqrt(1  v^2)

