The Philadelphia Experiment

Most of have probably heard of the Philadelphia Experiment. The common story is that the USN conducted experiments during 1943 involving somehow making a destroyer escort, the Eldridge, invisible and/or able to teleport. It's obviously complete nonsense, and several explanations have been offered for the story. But it turns out that the actual explanation is rather strange. The story we know today was created as a cover for something very different.

Philadelphia later in 1943

It turns out that the Philadelphia in question was not the city, but the ship. The light cruiser Philadelphia was a unit of the Brooklyn class, serving in the Mediterranean in 1943. She had gained distinction during the invasions of Morocco, Sicily and Salerno, and during the last invasion, she was the target of numerous German guided bombs. While she survived unscathed, several other ships did not, and the Allied navies began to scramble for an answer to the new weapons.

Until very recently, it was believed that the attempts to deal with the Hs 293 and Fritz X were limited to jamming and improved air defenses. However, recently-released files showed that an early anti-electronic weapon system was employed aboard Philadelphia in October of 1943 to attack the bomber bases. This mission has remained classified until very recently, as part of the ongoing classification of this specialized anti-vacuum-tube technology. It appears that during 1942, scientists working for the NDRC discovered that coatings used on the cathodes of most vacuum tubes were damaged by certain very specific combinations of radio-frequency signals. They immediately set to work weaponizing this, although the amount of power that had to be concentrated was high enough that it needed to be focused on point targets.

KG.100, the unit armed with the guided bombs, was based near Toulouse, and it seemed a likely target. It was relatively compact, its location could be established accurately, and taking it out would have a significant impact on the naval balance of power. Accordingly, Philadelphia was fitted out with specialized radio gear, and sent into the northern Mediterranean. On October 28th, the radio gear was switched on.

Unfortunately, they hadn't had a chance for a full-scale test, and it turned out that, while the signals shouldn't have combined to produce an effect aboard Philadelphia herself, they did, burning out most of her onboard electronic systems. She barely made it back to Oran, and then had to be sent back to the states for a full refit.

Information on what happened at the German airbase is less certain. As this information is very recent, the relevant records have not been examined in light of it, assuming they still exist at all. But the Hs 293s were even less effective than usual until about January, which is probably when they would have run through the stock on hand in late October.

Scientists immediately set to work on refining the anti-vacuum tube weapon, known as MVS for some reason. Unfortunately, all attempts to block the effects near the transmitter failed, so no more were mounted aboard ship. However, the use of confusingly-named high-frequency radio frequencies meant that the effects could work over the horizon, and several land-based transmitters were set up in England for use in support of the Normandy invasion. They were disguised as specialized radar sites or direction-finding arrays, a cover later used during the Cold War.

HAARP

So why are we only hearing about MVS now? The simple answer is that it's only now becoming less than very useful militarily. Many radar systems still contain vacuum tube-based transmitters, and Soviet electronics in particular used tubes long after they were abandoned in the West. As a result, the US continued to build MVS systems throughout the Cold War. The last and largest of these systems was given a public cover as an array for probing the upper atmosphere, a function it was in fact able to perform. It's known as HAARP, and I suspect the conspiracy theories about it being able to control the weather were intended to serve the same purpose as the "Philadelphia Experiment" nonsense.

It appears that MVS has finally been declassified because it was starting to leak. It's rather astonishing that they've managed to keep it secret for so long, but it's not an exciting-sounding technology, and plausible cover stories were easy to come by. It looks like the story about the Eldridge teleporting was created to sew confusion after a few vague documents were leaked referring to the Philadelphia experiment.