I really love the Earth's atmosphere. Air to breathe, rain from clouds, clouds that look like bunny rabbits…and an umbrella of atoms and molecules that shelters the surface from a withering onslaught of high energy particles – AKA cosmic rays, usually the nuclei of hydrogen atoms (protons) traveling at very high speeds – coming from space. The density (flux) of these particles is low, but some of them pack quite a wallop: their energy is measured in electronvolts (eV), and although the average cosmic ray has an energy of about 3 x 10 9 eV, some have energies on the order of 10 20 eV, which is about 40 million times more energy than we can create at the Large Hadron Collider! The good news is that our atmosphere is great at shielding the surface of our planet from cosmic rays – it works as well as four meters of solid concrete. But if we travel outside the atmosphere, our umbrella is gone, and we now have a problem.

The year is 2050 and super-intelligent robots have taken over the planet. Except you have no idea, because you're living in a computer simulation, depicting what life was like in 2015. Everything you see and touch right now has been created by robotic overlords who are using humanity as playthings in their virtual game. That's the radical theory put forward by a number of scientists over the years, who claim there is a possibility that our world as we know it is fake. The universe and everything you see in it is fake.