What's the coolest math or science fact you know?

The fusion taking place in the core of the sun is actually not that power-dense. One cubic meter of the incredibly hot and dense solar core only produces about 275 Watts of energy. You could fit two or three humans in the same space, and generate more heat from the waste heat of their bodies. It just goes to show how difficult a proposition it would be for us to make a useful fusion reactor here on earth. At least for plain old proton-proton fusion, it's just impossibly inefficient. (Which is why fusion experiments use deuterium, tritium, and other more exotic stuff) Now, of course, that glob of solar core generates 275 watts continuously for billions of years and the sun has a stupidly huge number of cubic meters of the stuff. That's why, with each of those pumping out that energy continuously, the sun burns with the firey passion of a million.... er, well, of just one sun. But that's still pretty hot. As far as energy density, though, your backyard barbecue is way bette