“The Philadelphia Experiment” is an urban legend about a U.S. Naval experiment that purportedly took place in 1943 at the Philadelphia Naval Shipyard in Pennsylvania, with the U.S. Navy destroyer escort USS Eldridge being rendered invisible to detection systems.
The tides of World War II had turned with the surrender of Italy to the Allies. With a sense that Germany was on the ropes, there was a great desire for the U.S. to shore up the gains the Allied forces had made. If they could get war craft into enemy waters without being seen, bringing with them the advantage of surprise, the war could end in short order. A ship with a cloaking device onboard could do the trick.
One problem: it’s not true.
In 1955, writer and astronomer Morris K. Jessup purportedly received letters from unknown sources describing the experiment. Known for his belief in the supernatural and extraterrestrial, Jessup published books including The Case for the UFO (1955), The UFO Annual (1956), and The Expanding Case for the UFO (1957).
According to David Ritchie’s 1994 book UFO: The Definitive Guide to Unidentified Flying Objects and Related Phenomena, Jessup claimed to have made a breakthrough regarding the Philadelphia Experiment on April 19, 1959. Just one day later, he was found dead in his car from carbon monoxide poisoning. The death was ruled a suicide, although conspiracy theorists believed he was silenced to keep from revealing things he was not meant to know.