“Fusion relies on the same basic process that powers the sun. You start with a gas—most research focuses on certain types of hydrogen—and get it extraordinarily hot, well over 50 million degrees Celsius, while it’s in an electrically charged state known as plasma. At these temperatures, the particles are moving so fast that they hit each other and fuse together, just as the hydrogen atoms in the sun do. When the hydrogen particles fuse, they turn into helium, and in the process they release a great deal of energy, which can be used to generate electricity. (Scientists have various ways of containing the plasma; the most common methods use either powerful magnets or lasers.)”