The Philadelphia Experiment is an alleged military experiment supposed to have been carried out by the U.S. Navy at the Philadelphia Naval Shipyard in Philadelphia, Pennsylvania, sometime around October 28, 1943. The U.S. Navy destroyer escort USS Eldridge (DE-173) was claimed to have been rendered invisible (or "cloaked") to enemy devices.
The story first appeared in 1955, in letters of unknown origin sent to a writer and astronomer, Morris K. Jessup. It is widely understood to be a hoax; the U.S. Navy maintains that no such experiment was ever conducted, that the alleged details of the story contradict well-established facts about USS Eldridge, and that the claims do not conform to known physical laws.
Origins of the story
In 1955, astronomer and UFO buff Morris K. Jessup, the author of the just published book The Case for the UFO, about unidentified flying objects and the exotic means of propulsion they might use, received two letters from a Carlos Miguel Allende (who also identified himself as "Carl M. Allen" in another correspondence) who claimed to have witnessed a secret World War Two experiment at the Philadelphia Naval Shipyard. In this experiment, Allende claimed the destroyer escort USS Eldridge (DE-173) was rendered invisible, teleported to New York, teleported to another dimension where it encountered aliens, and teleported through time, resulting in the death of several sailors, some of whom were fused with the ship's hull. Jessup dismissed Allende as a crackpot.
In early 1957, Jessup was contacted by the Office of Naval Research (ONR) in Washington, D.C., who had received a parcel containing a paperback copy of The Case for the UFO in a manila envelope marked "Happy Easter." The book had been extensively annotated in its margins, written with three different shades of pink ink, appearing to detail a correspondence among three individuals, only one of which is given a name: "Jemi." The ONR labelled the other two "Mr. A." and "Mr. B."
The annotators referred to each other as "Gypsies" and discussed two different types of "people" living in outer space. Their text contained non-standard use of capitalization and punctuation, and detailed a lengthy discussion of the merits of various elements of Jessup's assumptions in the book. There were oblique references to the Philadelphia Experiment (one example is that "Mr. B." reassures his fellow annotators who have highlighted a certain theory which Jessup advanced).  Based on the handwriting style and subject matter, Jessup concluded a large part of the writing was Allende's, and others have the same conclusion, that the three styles of annotations are from the same person using three pens.
The ONR funded a small printing of 100 copies of the volume by the Texas-based Varo Manufacturing Company, which later became known as the Varo edition, with the annotations therefore known as the Varo annotations.
Jessup tried to publish more books on the subject of UFOs, but was unsuccessful. Losing his publisher and experiencing a downturn in his personal life led him to commit suicide in Florida on 30, April 1959. 
George E. Simpson and Neal R. Burger published a 1978 novel titled Thin Air. In this book, set in the present day, a Naval Investigative Service officer investigates several threads linking wartime invisibility experiments to a conspiracy involving matter transmission technology.
Large-scale popularization of the story came about in 1979 when the famed linguist Charles Berlitz, who had written a best selling book on the Bermuda Triangle, and his co-author, ufologist William L. Moore published The Philadelphia Experiment: Project Invisibility, which purported to be a factual account. The book expanded on stories of bizarre happenings, lost unified field theories by Albert Einstein, and government coverups, all based on the Allende/Allen letters to Jessup.
Moore and Berlitz devoted one of the last chapters in The Philadelphia Experiment: Project Invisibility to "The Force Fields Of Townsend Brown," namely the experimenter and then-U.S. Navy technician Thomas Townsend Brown. Paul Violette's book Secrets of Anti-Gravity Propulsion[when?] also recounts some mysterious involvement of Townsend Brown.
The story was adapted into a 1984 time travel film called The Philadelphia Experiment, directed by Stewart Raffill. Though only loosely based on the prior accounts of the "Experiment", it served to dramatize the core elements of the original story. In 1990, Alfred Bielek, a self-proclaimed former crew-member of USS Eldridge and an alleged participant in the Experiment, supported the version as it was portrayed in the film. He added details of his claims through the Internet, some of which were picked up by mainstream news outlets.
- Note: Several different and sometimes contradictory versions of the alleged experiment have circulated over the years. The following synopsis recounts key story points common to most accounts.
The experiment was allegedly based on an aspect of some unified field theory, a term coined by Albert Einstein to describe a class of potential theories; such theories would aim to describe — mathematically and physically — the interrelated nature of the forces that comprise electromagnetic radiation and gravity, in other words, uniting the fields of electromagnetism and gravity into a single field.
According to some accounts, unspecified "researchers" thought that some version of this field would enable using large electrical generators to bend light around an object via refraction, so that the object became completely invisible. The Navy regarded this of military value and it sponsored the experiment.
Another unattributed version of the story proposes that researchers were preparing magnetic and gravitational measurements of the seafloor to detect anomalies, supposedly based on Einstein's attempts to understand gravity. In this version, there were also related secret experiments in Nazi Germany to find anti-gravity, allegedly led by SS-Obergruppenführer Hans Kammler.
There are no reliable, attributable accounts, but in most accounts of the supposed experiment, USS Eldridge was fitted with the required equipment at the Philadelphia Naval Shipyard. Testing began in the summer of 1943, and it was supposedly successful to a limited extent. One test resulted in Eldridge being rendered nearly invisible, with some witnesses reporting a "greenish fog" appearing in its place. Crew members complained of severe nausea afterwards. Also, reportedly, when the ship reappeared, some sailors were embedded in the metal structures of the ship, including one sailor who ended up on a deck level below that where he began and had his hand embedded in the steel hull of the ship, as well as some sailors who went "completely bananas." There is also a claim the experiment was altered after that point at the request of the Navy, limiting it to creating a stealth technology that would render USS Eldridge invisible to radar. None of these allegations have been independently substantiated.
The conjecture then claims that the equipment was not properly re-calibrated, but that in spite of this, the experiment was repeated on October 28, 1943. This time, Eldridge not only became invisible, but she disappeared from the area in a flash of blue light and teleported to Norfolk, Virginia, over 200 miles (320 km) away. It is claimed that Eldridge sat for some time in view of men aboard the ship SS Andrew Furuseth, whereupon Eldridge vanished and then reappeared in Philadelphia at the site it had originally occupied. It was also said that the warship went approximately ten minutes back in time.
Many versions of the tale include descriptions of serious side effects for the crew. Some crew members were said to have been physically fused to bulkheads while others suffered from mental disorders, some re-materialized inside out, and still others vanished. It is also claimed that the ship's crew may have been subjected to brainwashing, to maintain the secrecy of the experiment.
Evidence and research
The historian Mike Dash notes that many authors who publicized the "Philadelphia Experiment" story after that of Jessup appeared to have conducted little or no research of their own. Through the late 1970s, for example, Allende/Allen was often described as mysterious and difficult to locate, but Goerman determined Allende/Allen's identity after only a few telephone calls. Others speculate that much of the key literature emphasizes dramatic embellishment rather than pertinent research. Berlitz's and Moore's account of the story (The Philadelphia Experiment: Project Invisibility) claimed to include factual information, such as transcripts of an interview with a scientist involved in the experiment, but their work has also been criticized for plagiarising key story elements from the novel Thin Air which was published a year earlier.
Personnel at the Fourth Naval District have suggested that the alleged event was a misunderstanding of routine research during World War II at the Philadelphia Naval Shipyard. An earlier theory was that "the foundation for the apocryphal stories arose from degaussing experiments which have the effect of making a ship undetectable or 'invisible' to magnetic mines." Another possible origin of the stories about levitation, teleportation and effects on human crew might be attributed to experiments with the generating plant of the destroyer USS Timmerman (DD-828), whereby a higher-frequency generator produced corona discharges, although none of the crew reported suffering effects from the experiment.
Observers have argued that it is inappropriate to grant credence to an unusual story promoted by one individual, in the absence of corroborating evidence. Robert Goerman wrote in Fate magazine in 1980, that "Carlos Allende" / "Carl Allen", who is said to have corresponded with Jessup, was Carl Meredith Allen of New Kensington, Pennsylvania, who had an established history of psychiatric illness, and who may have fabricated the primary history of the experiment as a result of his mental illness. Goerman later realized that Allen was a family friend and "a creative and imaginative loner ... sending bizarre writings and claims."
The USS Eldridge was not commissioned until August 27, 1943, and it remained in port in New York City until September 1943. The October experiment allegedly took place while the ship was on its first shakedown cruise in The Bahamas, although proponents of the story claim that the ship's logs might have been falsified or else still be classified.
The Office of Naval Research (ONR) stated in September 1996, "ONR has never conducted investigations on radar invisibility, either in 1943 or at any other time." Pointing out that the ONR was not established until 1946, it denounces the accounts of "The Philadelphia Experiment" as complete "science fiction."
A reunion of Navy veterans who had served aboard USS Eldridge told a Philadelphia newspaper in April 1999 that their ship had never made port in Philadelphia. Further evidence discounting the Philadelphia Experiment timeline comes from USS Eldridge’s complete World War II action report, including the remarks section of the 1943 deck log, available on microfilm.
Researcher Jacques Vallée describes a procedure on board USS Engstrom (DE-50), which was docked alongside the Eldridge in 1943. The operation involved the generation of a powerful electromagnetic field on board the ship in order to deperm or degauss it, with the goal of rendering the ship undetectable or "invisible" to magnetically fused undersea mines and torpedoes. This system was invented by a Canadian, Charles F. Goodeve, when he held the rank of commander in the Royal Canadian Naval Volunteer Reserve, and the Royal Navy and other navies used it widely during World War II. British ships of the era often included such degaussing systems built into the upper decks (the conduits are still visible on the deck of HMS Belfast (C35) in London, for example). Degaussing is still used today. However, it has no effect on visible light or radar. Vallée speculates that accounts of USS Engstrom's degaussing might have been garbled and confabulated in subsequent retellings, and that these accounts may have influenced the story of "The Philadelphia Experiment."
Vallée cites a veteran who served on board USS Engstrom and who suggests it might have travelled from Philadelphia to Norfolk and back again in a single day at a time when merchant ships could not: by use of the Chesapeake and Delaware Canal and Chesapeake Bay, which at the time was open only to naval vessels. Use of that channel was kept quiet: German submarines had ravaged shipping along the East Coast during Operation Drumbeat, and thus military ships unable to protect themselves were secretly moved via canals to avoid the threat. The same veteran claims to be the man that Allende witnessed "disappearing" at a bar. He claims that when the fight broke out, friendly barmaids whisked him out of the bar before the police arrived, because he was under age for drinking. They then covered for him by claiming that he had disappeared.
- Diffused lighting camouflage, prototype Royal Canadian Navy counter-illumination system for ships
- List of conspiracy theories
- Montauk Project
- Morris K. Jessup
- Yehudi lights, prototype US Navy counter-illumination system for aircraft
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- The Philadelphia Experiment from A-Z
- The Philadelphia Experiment by the DEPARTMENT OF THE NAVY - NAVAL HISTORICAL CENTER
- PDF version of "The Case for the Unidentified Flying Object" by Morris K. Jessup - 2003 transcription of the Office of Naval Research (ONR) annotated "Varo edition", with three-color notes supposedly by Carlos Miguel Allende