“Believe it or not, light has momentum,” I said. “It exerts a force. If you were out in space and you turned on a flashlight, you’d get a teeny, tiny amount of thrust from it.” “I didn’t know that.” “Now you do. And a teeny-tiny thrust on a teeny-tiny mass can be an effective form of propulsion. I measured the dots’ average mass at about twenty picograms. That took a long time, by the way, but that lab equipment is awesome. Anyway, the movement I see is consistent with the momentum of the emitted light.”
