The legend of the Philadelphia Experiment originated from letters written by Carl M. Allen in 1955.

In late 1955, an ex-merchant mariner named Carl M. Allen sent annotated books and letters to a U.S. Navy research organization and a prominent UFO author. He claimed to have personally witnessed the USS Eldridge vanish from Philadelphia and instantly teleport to Virginia. This single source, later exposed as a complete hoax, became the sole foundation for decades of conspiracy theories, books, and science fiction films.