Talents, Incorporated by Murray Leinster — Read

There was a fleet on the way to Kandar. It could not be said to be traveling in space, of course. If there had been an observer somewhere, he could not conceivably have detected the ships. There would be no occultations of stars; no blotting out of any of the hundreds and thousands of millions of bright specks which filled all the firmament. There would be no drive-radiation which even the most sensitive of instruments could pick up. The fleet might be at one place to an observer's right -- where it was imperceptible -- and then it might be at a place to the observer's left -- where it was undetectable -- and nobody could have told the difference.

Actually, each ship of the Mekinese fleet was in overdrive, which meant that each had stressed the space immediately around it so that it was like a cocoon of other-space; as if it were out of this cosmos altogether and in another. In sober fact, of course, nothing of the sort had happened. An overdrive field changed the physical constants of space. The capacity of a condenser in an overdrive field was different from that of a condenser out of it. The self-induction of a coil in an overdrive field was not the same as in normal space. Magnetic and gravitational fields also did not follow the same laws in stressed space as in unstressed extension. The speed of light was different. Inertia was different. In short, a ship could drive at many hundreds of times the velocity of light and the laws of Einstein did not apply, because his laws referred to space that men had not tampered with.