25. The Speed of Light
Everybody loves to imagine themselves flying through the galaxy at the speed of light, at roughly 299,792,458 meters per second; however, the reality might be less fun and a lot more fatal. When coming in contact with an object moving at light speed, hydrogen atoms transform into intensely radioactive particles that could easily wipe out the crew of a starship and destroy electronics in seconds. Just a few stray wisps of hydrogen gas floating through the cosmos could have a radioactive output equivalent to a proton beam created by the Large Hadron Collider.