My question is concerning wikipedia article on Oh-my-God particle, to be precise, this paragraph:
This particle had so much kinetic energy it was travelling at 99.99999999999999999999951% the speed of light. This is so near the speed of light that if a photon were travelling with the particle, it would take 220,000 years for the photon to gain a 1 centimeter lead. Also, due to special relativity effects, from the proton's reference frame it would have only taken it around 10 seconds to travel the 100,000 light years across the Milky way galaxy. 
I would like to see demonstration how the special relativity effect allows the particle to travel the distance in 10 seconds.
Thanks for all responses, I have one more question: you all explain the situation from the "Proton reference frame". What about from "Observer reference frame"? We can imagine the observer (and also the whole universe around) moving at 99.99999999999999999999951% the speed of light comparing to the "stationary" proton. How will the proton look from this reference frame?
This was not a homework, just a weekend curiosity while reading wikipedia :-)