Scientists have developed a new kind of tiny motor — which they term a “microrocket” — that can propel itself through acidic environments, such as the human stomach, without any external energy source, opening the way to a variety of medical and industrial applications. Their report in the Journal of the American Chemical Society describes the microrockets traveling at virtual warp speed for such devices. A human moving at the same speed would have to run at a clip of 400 miles per hour.