"Today we’re going to talk about what it means to have a swarm of arklets," he said. "In normal space, like on Earth, we use three numbers to tell where something is. Left-right, forward-back, up-down. The x, y, and z axes from your high school geometry class. Turns out that this doesn’t work so well in orbit. Up here we need six numbers to fully specify what orbit an object, such as an arklet, happens to be in. Three for position. But another three for velocity. If you’ve got two objects that share the same six numbers, they’re in the same place. Right now, my six numbers are the same as those of this arklet that I’m floating in, and so we’re moving through space together. But if one or more of my numbers changed, you’d see me drifting."