Gravitational redshift was an optical illusion that occurred as an object fell into a black hole. As the speed of the falling object exceeded the frequency of the light it emitted, to an outside observer it would appear to have stopped just outside the black hole.
In 2259, Captain Christopher Pike took advantage of gravitational redshift to deceive a Gorn destroyer into believing that the USS Enterprise had been destroyed, by accelerating toward the central black hole of the Finibus system while detonating an AP 350 atmospheric processor behind it. Lieutenant Erica Ortegas termed this the "Pike Maneuver". (SNW: "Memento Mori")