Let's say you're in an interstellar spaceship traveling at a billion miles an hour towards another star system and you hit a hydrogen atom in space. What kind of damage will it cause and what kind of energy is it?
Hmm... let's see. 1 billion miles per hour = 447 040 000 metres per second. The speed of light is 300 000 000 metres per second. So, the answer is that you couldn't be travelling at a billion miles an hour.
Haha, well as James says, you're faster than light so physics has gone to hell. But for fun, lets pretend relativity doesn't exist. Mass of hydrogen atom = 1.67*10^-27 kg Velocity = 4.5*10^8 m/s (I'll just believe James on the conversion here, I'm lazy) Kinetic energy = 1/2mv^2 ~ 10^-10 J Which would be pretty much nothing still, as far as us macroscopic objects go. You wouldn't notice it. However, if you choose a slower speed and let us use relativity then you can make the energy of the atom infinite as you go arbitrarily close to the speed of light. It still wouldn't do anything if it hit you though, it would just go straight through you and you'd never be the wiser. Might leave a couple of free radicals in your body somewhere, better eat some food with anti-oxidants Please Register or Log in to view the hidden image!.
This is actually one of the reasons why interstellar travel is so dangerous. The Earth's core gives us a very strong magnetic field, which shields us from incoming charged particles. IF we didn't have a huge magnetic field, we'd be hit by much more cosmic radiation, and we'd probably all get cancer. When you're on a space ship far from earth, you don't have a huge magnetic field shielding you from cosmic radiation. So your space ship is constantly bombarded by high energy particles, which interact with its hull. The particles can either tunnel through the hull and hit you, or they can hit the hull and shower. ``Showering'' is what happens in a very high energy nuclear collision---the proton from the hydrogen atom you hit hits a nucleus of iron in your ships hull (or any other nucleus that happens to be hanging around) and produces a bunch of sub-atomic particles: more protons, neutrons, pions, kaons, alpha particles ... All of these particles decay, and what you're left with is a bunch of free neutrons (bad), x rays (bad) and beta radiation (bad). The subatomic particles can decay inside you, or inside your ship, or they can interact with you, producing another shower of sub-atomic particles inside your body. Presumably, the only way to solve this problem is to generate a huge magnetic field around your space ship, or a magnetic field with a huge radius. Otherwise, you'd get to Alpha Centauri to kill some blue kitties, and find that you have cancer.
