Scuba Diving -> Electrical Outlet

I’m surprised “electrical outlet” was a “Hard” Pictionary result. That seems like a pretty easy thing to draw. Regardless, let’s get diving.

Scuba diving involves taking a tank of oxygen underwater, which is necessary because humans, tragically, are only fish in the most pedantic of senses. We need to breathe oxygenated air, and the oxygen we breathe comes from plants: We’d suffocate without them, while they’d be fine without us. They make oxygen using plentiful carbon dioxide and water. But where does that oxygen come from—the stuff in the carbon dioxide and water molecules? We’ve got a ways to go, so let’s make this answer quick: Mostly molten rocks, and also some dead stuff.

But that doesn’t satisfy me yet. Where do the actual oxygen atoms come from that have been kicking around our planet for billions of years? They don’t come from chemistry or geology. They come from physics. Stars bigger than the Sun make oxygen all the time out of carbon and hydrogen (and another hydrogen), although admittedly most of it then turns into nitrogen. Dying stars of all stripes make more lasting oxygen by smashing together carbon with helium. When really big stars die, they explode in a supernova, blasting oxygen and other elements out into the cosmos. (Sun-sized stars typically hold onto the heavier elements they make, although evidence is mounting that they often end up growing big after they die and exploding anyway.) We breathe—and are made from—the ashes of ancient stellar explosions.

Stars themselves are made of plasma, which is either a fourth state of matter or a super-hot gas, depending on whom you ask. If you ask someone who’s focused on molecular motion, plasmas and gases are the same thing: Substances whose molecules zing around so quickly that they don’t clump together. But if you ask someone focused on conductivity, they’ll say plasmas and gases are quite different. In a plasma, the molecules move so fast that electrons are knocked off of them, creating a sea of charge through which electricity can flow quite easily. Plasmas are conductors, while most gases are much too diffuse to conduct electricity.

Back down on Earth, of course, we don’t have to seek out a plasma to find something conductive. We have metals that we form into wires and plugs. Plug something in and electricity—electrons—flow down the conductive wire from the electrical outlet.