The Philadelphia Experiment is the name of an alleged naval military experiment said to have been carried out at the Philadelphia Naval Shipyard

Philadelphia Naval Shipyard

The Philadelphia Naval Business Center, formerly known as the Philadelphia Naval Shipyard and Philadelphia Navy Yard, was the first naval shipyard of the United States. The U.S. Navy reduced its activities there in the 1990s, and ended most of them on September 30, 1995...

 in Philadelphia, Pennsylvania

Philadelphia, Pennsylvania

Philadelphia is the largest city in the Commonwealth of Pennsylvania and the county seat of Philadelphia County, with which it is coterminous. The city is located in the Northeastern United States along the Delaware and Schuylkill rivers. It is the fifth-most-populous city in the United States,...

, USA sometime around October 28, 1943. It is alleged that the U.S. Navy

United States Navy

The United States Navy is the naval warfare service branch of the United States Armed Forces and one of the seven uniformed services of the United States. The U.S. Navy is the largest in the world; its battle fleet tonnage is greater than that of the next 13 largest navies combined. The U.S...

 destroyer escort

Destroyer escort

A destroyer escort is the classification for a smaller, lightly armed warship designed to be used to escort convoys of merchant marine ships, primarily of the United States Merchant Marine in World War II. It is employed primarily for anti-submarine warfare, but also provides some protection...

 USS Eldridge

USS Eldridge (DE-173)

USS Eldridge , a , was a ship of the United States Navy named for Lieutenant Commander John Eldridge, Jr., a hero of the invasion of the Solomon Islands. Its keel was laid down by the Federal Shipbuilding and Dry Dock Company in Newark, New Jersey. Eldridge was launched on 25 July 1943, sponsored...

 was to be rendered invisible

Invisibility

Invisibility is the state of an object that cannot be seen. An object in this state is said to be invisible . The term is usually used as a fantasy/science fiction term, where objects are literally made unseeable by magical or technological means; however, its effects can also be seen in the real...

 (or "cloaked

Cloaking device

Cloaking devices are advanced stealth technologies still in development that will cause objects, such as spaceships or individuals, to be partially or wholly invisible to parts of the electromagnetic spectrum...

") to enemy devices. The experiment is also referred to as Project Rainbow

Project Rainbow

Project Rainbow was the name given by the CIA to a research project aimed at reducing the radar cross section of the Lockheed U-2 to reduce the chance that it would be detected and tracked by Soviet radars during its overflights of the USSR.-Early Flights:...

.

The story is widely regarded as a hoax

Hoax

A hoax is a deliberately fabricated falsehood made to masquerade as truth. It is distinguishable from errors in observation or judgment, or rumors, urban legends, pseudosciences or April Fools' Day events that are passed along in good faith by believers or as jokes.-Definition:The British...

. The U.S. Navy maintains that no such experiment occurred, and details of the story contradict well-established facts about the Eldridge, as well as the known laws of physics.