We Have No Idea: A Guide to the Unknown Universe

by Jorge Cham

But here is the mind-blowing fact about particles this high on the energy spectrum: we don’t know anything in the universe that is capable of making such high-energy particles. That’s right, we are being bombarded by millions of extremely high-energy particles on a daily basis, and we have no idea what could be creating them. If you ask astrophysicists75 to estimate what the highest speed a particle anywhere in space could ever have (based on what we know right now), they will (a) thank you for asking them such a cool question, (b) come up with crazy situations like particles surfing on exploding supernovas or black holes swinging particles around like slingshots, and (c) still come up short. Based on all the things we know about in the universe right now, the highest energy a particle could have in space is about 1017 eV, which is still more than a thousand times less energetic than the ones hitting the Earth every day.