The Philadelphia Experiment: The Navy's Alleged Invisibility Test

The Philadelphia Experiment stands as one of the most enduring conspiracy theories in American military history. According to the story, in October 1943, the U.S. Navy conducted a secret experiment aboard the destroyer escort USS Eldridge (DE-173) at the Philadelphia Naval Shipyard. Using powerful electromagnetic generators, the Navy allegedly rendered the ship invisible to radar — and possibly to the naked eye — before the vessel spontaneously teleported to Norfolk, Virginia, and back. The experiment reportedly had catastrophic effects on the crew, with sailors allegedly fused into the ship’s metal structure, driven insane, or phased in and out of visibility.

The Navy has consistently denied the experiment ever took place. The story’s origins are traceable to a single, troubled source. Yet the Philadelphia Experiment refuses to die, continuing to generate books, films, documentaries, and passionate debate decades after its supposed occurrence.

The Origins: Carlos Allende’s Letters

Morris K. Jessup and the Allende Letters

The Philadelphia Experiment story traces back not to a military leak or government whistleblower, but to a series of strange, rambling letters sent to astronomer and author Morris K. Jessup beginning in 1955. Jessup had published The Case for the UFO in 1955, a book exploring the possibility that UFOs were real and that anti-gravity technology might explain their flight characteristics. Shortly after publication, he began receiving letters from a man identifying himself as Carlos Miguel Allende (also using the name Carl M. Allen). Writing in an erratic style with unusual capitalization, colored inks, and underlined passages, Allende made extraordinary claims.

According to Allende, he had been a sailor aboard the SS Andrew Furuseth, a merchant marine vessel, in October 1943. From the deck of the Furuseth, Allende claimed to have witnessed the USS Eldridge become “invisible” and then teleport from the Philadelphia Naval Shipyard to Norfolk, Virginia — a distance of over 200 miles — before reappearing in Philadelphia. He described the effects on the Eldridge’s crew in horrifying detail: men fused into the ship’s bulkheads, some who became invisible and could not reverse the effect, others who went violently insane, and still others who simply vanished forever.

Allende referenced Albert Einstein’s Unified Field Theory as the scientific basis for the experiment, claiming that Einstein had completed the theory but suppressed it after learning of the Navy experiment’s human cost.

The Annotated Copy

The story took a stranger turn when someone mailed a copy of Jessup’s book to the Office of Naval Research (ONR) in Washington, D.C. The book had been extensively annotated in three different colors of ink, with marginal notes discussing UFOs, alien races (referred to as “L-Ms” and “S-Ms”) and advanced technology. The ONR officers who received it — Captain Sidney Sherby and Commander George Hoover — were intrigued enough to have a limited run of the annotated book printed by a Texas publishing firm (the Varo Edition), though this appears to have been personal interest rather than an official investigation.

Jessup, who had been struggling with personal and financial difficulties, died in 1959 in what was ruled a suicide. Some researchers have claimed his death was connected to his knowledge of the Philadelphia Experiment, though there is no evidence to support this.

The Story as Commonly Told

The Experiment

According to the most developed version of the narrative (largely shaped by Charles Berlitz and William Moore’s 1979 book The Philadelphia Experiment), the sequence of events was as follows:

In the summer of 1943, the Navy conducted preliminary tests on the USS Eldridge at the Philadelphia Naval Shipyard. The ship had been fitted with massive electromagnetic generators, supposedly based on principles derived from Einstein’s Unified Field Theory and developed by scientists working under the Rainbow Project (also referred to as Project Rainbow).

The initial test, reportedly conducted in July 1943, achieved partial invisibility — the ship supposedly became shrouded in a greenish fog and became nearly invisible to observers, though an outline of the hull remained visible. The crew reported severe nausea and disorientation.

The October Test

On October 28, 1943, the full-scale experiment was allegedly conducted. The generators were activated, and the USS Eldridge reportedly became completely invisible — not merely to radar, but to the naked eye. A greenish-blue fog enveloped the vessel, and then the ship vanished entirely from the Philadelphia shipyard.

According to the story, the Eldridge materialized in Norfolk, Virginia, where it was reportedly witnessed by crew members of the SS Andrew Furuseth and other vessels. After several minutes, the ship vanished from Norfolk and reappeared in Philadelphia.

The Crew Effects

The most horrifying aspect of the narrative concerns the alleged effects on the Eldridge’s crew:

• Some sailors were reportedly found partially embedded in the ship’s metal structure — fused with bulkheads and decking as though the solid matter of their bodies and the ship had momentarily occupied the same space
• Others were said to have become invisible and could not reverse the effect
• Several crew members allegedly went violently insane
• Some reportedly “froze” — becoming immobile and invisible, requiring other crew members to physically touch them to bring them back to normal (a process described as “laying on of hands”)
• Others purportedly phased in and out of visibility for years afterward, a condition referred to as “going blank”
• At least one crew member allegedly disappeared entirely, vanishing in front of his family at a restaurant

What the Evidence Actually Shows

The USS Eldridge’s Deck Logs

The Navy released the deck logs of the USS Eldridge, which show the ship was not in Philadelphia in October 1943. According to these records, the Eldridge was on its shakedown cruise in the Bahamas and was subsequently assigned to convoy escort duty in the Atlantic. The ship was commissioned on August 27, 1943, at the New York Navy Yard, not in Philadelphia.

The SS Andrew Furuseth

Records of the SS Andrew Furuseth’s voyages have been examined, and researchers have found no overlap between the Furuseth’s documented locations and the alleged timeline of events in Philadelphia.

Carlos Allende/Carl Allen

Allende was eventually tracked down by researchers. He was identified as Carl Meredith Allen, a Pennsylvania native with a history of mental health issues and a tendency toward elaborate fabrication. In 1969, Allen himself wrote to the Aerial Phenomena Research Organization (APRO) confessing that “the Philadelphia Experiment was a hoax” that he had made up. He subsequently recanted this confession, claiming he had been pressured into it.

Allen’s background revealed no verifiable evidence of his claimed service aboard the Andrew Furuseth during the alleged timeframe, though he did serve in the Merchant Marine during World War II.

Einstein’s Unified Field Theory

The story’s scientific premise — that Einstein had completed a Unified Field Theory that could bend light and space around an object — does not align with the historical record. Einstein worked on unified field theories throughout his later career but never achieved a successful one. His incomplete 1943 work on the topic bore no relationship to electromagnetic invisibility or teleportation.

Degaussing: The Likely Kernel of Truth

Many researchers believe the Philadelphia Experiment story may have originated from a garbled understanding of degaussing — a real and well-documented naval technology. During World War II, ships were wrapped with large electrical cables and subjected to powerful electromagnetic fields to neutralize their magnetic signatures, making them “invisible” to magnetic mines and torpedoes. This technology was classified during the war, and the sight of a ship wrapped in cables and surrounded by electrical equipment could easily be misinterpreted by an uninformed observer.

The Navy has stated that the only experiment conducted in Philadelphia in 1943 related to the Eldridge was degaussing operations.

The Berlitz and Moore Book

The Philadelphia Experiment entered mainstream awareness primarily through the 1979 book The Philadelphia Experiment: Project Invisibility by Charles Berlitz and William L. Moore. Berlitz, who had previously authored the bestselling The Bermuda Triangle, combined Allende’s claims with additional research, interviews, and speculation to construct a detailed narrative.

Moore later became controversial in the UFO community when it was revealed that he had been acting as a conduit for U.S. intelligence disinformation operations targeting UFO researcher Paul Bennewitz. This revelation cast doubt on Moore’s reliability as a researcher, though the Philadelphia Experiment book had been published years before his involvement with intelligence agencies became known.

Declassified Documents

Freedom of Information Act (FOIA) requests have produced relevant documents over the decades:

• The ONR has released statements categorically denying the experiment
• The Eldridge’s deck logs and service records are publicly available and contradict the narrative
• No documents referencing “Project Rainbow” (in the context of invisibility experiments) have been found in declassified Navy archives
• There was a real “Project Rainbow” during WWII, but it dealt with radar countermeasures, not invisibility

The absence of any documentary trace of the experiment in the extensive declassified WWII archives is perhaps the strongest argument against its occurrence. The Manhattan Project, despite being one of the most tightly held secrets in American history, left an enormous paper trail. An experiment involving an entire destroyer escort and its crew would have generated significant documentation.

The USS Eldridge After the War

The Eldridge served through the end of World War II without further incident. In 1951, the ship was transferred to Greece under the Mutual Defense Assistance Program and renamed the HS Leon (D-54). It served in the Hellenic Navy until 1992, when it was sold for scrap. Greek sailors who served aboard the vessel reported no unusual phenomena.

Former crew members of the Eldridge who have been located and interviewed have uniformly denied that any unusual experiment took place. Bill Van Allen, who served aboard the Eldridge in 1943, stated in interviews that nothing out of the ordinary occurred during his service and that the story was complete fiction.

Cultural Impact

Despite the absence of credible evidence, the Philadelphia Experiment has had an enormous cultural impact:

• Films: The Philadelphia Experiment (1984) and its sequel (1993) dramatized the story
• Television: Numerous documentary programs have covered the case
• Video games and fiction: The concept of military experiments in teleportation and invisibility has become a staple of science fiction and conspiracy fiction
• Conspiracy culture: The Philadelphia Experiment serves as a foundational text for narratives about secret government technology programs

What We Can Conclude

The Philadelphia Experiment, as described in the Allende letters and the Berlitz-Moore book, almost certainly did not occur. The documentary evidence contradicts the narrative, the sole primary source was an unreliable witness who confessed to fabrication, and the scientific premise is unsupported by physics.

However, the story illuminates several genuine phenomena: the wartime secrecy surrounding technologies like degaussing and radar countermeasures, the human tendency to construct elaborate narratives from fragmentary information, and the enduring appeal of the idea that secret military technology exists far beyond what is publicly acknowledged. In an era of genuine government UAP investigations and declassified military programs, the Philadelphia Experiment serves as both a cautionary tale about uncritical acceptance of extraordinary claims and a reminder that governments do, in fact, conduct classified experiments — just rarely the ones conspiracy theorists imagine.

Sources

• Wikipedia search: “The Philadelphia Experiment: The Navy”
• Chronicling America — Historic US newspapers (1690–1963)