The Philadelphia Experiment:


An Optical and Radar Invisibility Technique Deduced from the World War II "Philadelphia Experiment" Legend.

by Alexander Strang Fraser.

Copyright Alexander Strang Fraser, 1991 Nelson, BC, Canada.


What has become known as the "Philadelphia Experiment" originated with a letter written by Carl M. Allen (alias Carlos Miguel Allende) to Dr. Morris K. Jessup. This together with additional information and speculation has led to the growth of an intriguing legend which includes the invisibility and teleportation of the US Navy destroyer escort USS Eldridge (DE 173) in October 1943 on the US east coast. Furthermore, these phenomenal results were supposedly achieved by the Office of Naval Research (ONR) through the use of a Unified Field Theory (UFT) by Einstein, and strong magnetic fields. In addition, severe side effects were to have been experienced by the crew.

The Navy has denied that the ONR has ever performed any invisibility investigations (1,2). This appears to be technically correct with respect to the "Philadelphia Experiment" (PX) -- but what of any possible applicable activities of the Naval Research Laboratory (NRL), D.C.? (Table 1, Map 1 [not reproduced here])

This report shows that various aspects of PX are consistent with a technology that can make a ship invisible. Although this is not direct evidence of realities behind the legend, the coincidence is notable.


(selected events)

1923- July 2-- US Naval Research Laboratory (NRL) opened-- D.C. (3)
1941- Dec. 7-- Pearl Harbor; Dunninger submitted ship invisibility idea to Navy after this (4)
1942- May 8-- US aircraft carrier Lexington lost (5)
1942- June 7-- US aircraft carrier Yorktown lost (6)
1942- Sept. 15-- US aircraft carrier Wasp lost (7)
1942- Oct. 26-- US aircraft carrier Hornet lost (8)
1942- Dec. 2-- University of Chicago (Fermi et al) reactor successful (9)
1943- Feb. 22-- Eldridge construction commenced-- Newark, NJ (10)
1943- March-- Nazi U-boat success peaks (11)
1943- spring-- Allied committee appointed to monitor Nazi missile situation (12)
1943- July 25-- Eldridge launched (13)
1943- Aug. 27-- Eldridge commissioned-- New York (14,15)
1943- Sept.-- Eldridge shakedown and escort duties through to late Dec. (16)
1943- fall-- British discovered Nazi missiles to be of two types (V-1&2)(17)
1943- Oct. 4-- SS Andrew Furuseth in port-- Newport News, VA (18)
1943- Oct.-- PX (19,20)
1943- Oct. 25-- Furuseth departed for Oran, N. Africa (21)
1943- late-- US Mark 14 torpedo problems all solved (22)
1943- late Dec.-- Eldridge trained near Block Island, RI (23)
1944- Jan.-- Eldridge assumed convoy escort duty in Atlantic (24)
1944- June 6-- D-Day (25)
1944- June 13-- First V-1 attacks against England (26)
1944- June 19-- Imperial Japanese aircraft carriers Shokaku & Taiho sunk by US subs (27)
1944- Oct. 24-- US aircraft carrier Princeton lost (28)
1944- Nov. 29-- Imperial Japanese aircraft carrier Shinano sunk by US sub (29)
1944- Dec. 19-- Imperial Japanese aircraft carrier Unryu sunk by US sub (30)
1945- early-- NRL transferred from Bureau of Ships to Office of Research and Inventions (ORI) (31)
1945- July 16-- First A-bomb explosion-- Alamogordo, NM (32)
1946-- Office of Naval Research (ONR) succeeded ORI (33,34)
1956- Jan. 13-- Carl M. Allen's first letter (rural New Kensington, PA home address (35)) received by Jessup (36)


Naval forces saw a transition during WWII in which the aircraft carrier had, by 1943, superseded the battleship as the preeminent fleet vessel. (37) One way of dealing with Imperial Japanese carriers was obviously by way of submarine attack. However, US submarine success was severely limited during the first part of the war by Mark 14 torpedo problems, all of which were not rectified until late 1943 (Table 1).(22) During this period alternative systems would have been attractive.

The loss in importance of the battleship was an example of the bypassing of an established system through a fundamental advance (the use of aircraft to significantly extend naval range) to gain military advantage. After the idea of an invisible ship was advanced (4), the concept of an invisible destroyer (a fast, stealthy, raiding vessel to sink carriers) to bypass the submarine should have become apparent.

Any enthusiasm for such a concept would likely not have been dampened until the success of, or the reasonable prospect of the success of, US subs in 1944 (Table 1) with fully functional Mark 14's and the new electric Mark 18 and acoustical Mark 27 torpedoes. (38)


The central feature in PX appears to have been some kind of field (39). It has been suggested that degaussing was involved (40) and that this type of equipment was used to form a strong magnetic field (41). C.M. Allen inferred that an Einsteinian Unified Field Theory (UFT) was involved (42).

Any circumstances that would produce space-time warps so as to cause teleportation (and thus apparent invisibility) would exhibit enormous gravitational anomalies. Such anomalies are absent from PX. Apart from a UFT magnetism-warp connection, the supposed magnetic fields would have no invisibility implications. Magnetic fields and a UFT would therefore seem to be parts of the legend irrelevant to invisibility.

The nature of the field, however, is discernible from empirical descriptions. C.M. Allen used the term "scorch" (43) and referred to fire (44) and optical wavering like that seen through heated air (45). The field therefore appears to have had a substantial heat component and will here be dubbed the 'thermal field'.


The most obvious connection between heat and altered visibility is the variety of mirage phenomena. Indeed, the idea of applying a mirage to make US Navy ships invisible was submitted by illusionist? Joseph Dunninger early in the Pacific War (Table 1) (4). To make a ship invisible a mirage effect called 'sinking' (46) is applicable.

If one ignores differences in perspective, an idea of 'sinking' can be achieved by visualizing a ship sailing away. As the ship follows the curvature of the earth it appears to sink into the horizon with only the top of the mast visible before it finally disappears.

In mirage "sinking', rather than moving the ship on a curved surface, the relative height of the ship with respect to the intervening surface can in effect be lowered by curving the path of the light from the ship. If the temperature of the air around the ship decreases (i.e., density & refractive index increases) with height, the light rays are bent upwards (Fig. I, not shown here)(47). As the temperature gradient increases in magnitude the ship will appear to sink into a "vanishing line" (48) near the surface of the sea until, with sufficient magnitude, it disappears entirely (Fig. II, not shown here). At this point the image of the ship can only be seen if one is above the line-of-sight of the observer, who would be in the Image-Free Zone of Figure I.

The inverted image in Figure II is not essential to the invisibility situation but is simply typical of the 'inferior' mirage (49) conditions during which 'sinking' can occur (50).

The technique of artificial mirage-related ship invisibility is paralleled by the probable natural mirage-related disappearances of Bouvet Island (1772, 1774, 1775, 1843, 1845) (51) and Easter Island (1928) (52).


For a medium of given refractive index, deviation of electromagnetic waves by refraction decreases with increasing wavelength. This difference in deviation experienced by different wavelengths is called dispersion and the magnitude of it decreases with decreasing refractive index (53). Since the refractive index of air (approx. 1.0003) (54) is almost equal to that of vacuum (1), dispersion in air is slight (55). Radar beams, being of longer wavelength than light, are bent or curved (56) slightly less than light but are still affected by the same atmospheric circumstances. An example of similar activity is the ducting along an inversion layer of both A) light (57) (e.g., Novaya Zemlya effect (58)) and B) radar (59,60) (e.g., extended range in the Mediterranean during WWII (61)).


To make mirage-related light and radar invisibility effective in all azimuths, the thermal field would have to extend laterally from, and encircle, the ship. This is consistent with C.M. Allen's approximately 200 yard diameter "oblate spheroidal" description.(62)

To generate the thermal field, energy must be distributed from the ship in a form which air can absorb. This can be done by the use of high frequency sound-- which was witnessed during a dock-side test.(63) Since making a ship an acoustical beacon would depreciate the invisibility advantage, the use of inaudible ultrasonics would be necessary. There are a considerable number of details in the PX legend that are consistent with the use of ultrasonics (Table II).

Since the absorption of sound in air escalates with frequency (64) and since considerable lateral dimensions seem necessary, there are limits as to how high the frequency can be raised.

It should be noted that the effects of high power ultrasonics on any PX crew would have been a disincentive to further project development. Besides this, various operational problems would exist that might be expensive to fix or unsolvable (Table III).


Selected PX Details and their Ultrasonic Explanation (?) direct & (indirect)

A) (hot air)
B) body heating by ultrasonic diathermy(72)
C) heating of absorptive clothing(73,74)
D) "burning sensation" due to vibration damping between fingers(75)

excessive heating of absorptive materials(73,74)

crew members who acted drunk(65)
A) equilibrium loss(76)
B) (giddiness due to heat exhaustion)(77)

(fainting due to heat exhaustion)(78)

sense of being "stuck"(67) or frozen(68)
paralysis due ro effect on nerves(79)

A) central nervous system lesions(80)
B) (brain damage due to heat stroke)(81)

green(70) fog(71)
fog: from water(82) due to activity of harmonics?(83)
green: water sonoluminescence?(84)


Problems and Potential Solutions

nerve effects
separation of crew from ultrasonic-thermal field by altering deck duties and/or using special enclosures/suits

heat exhaustion
same as above (though of course ultrasonics and heat require different types of shielding)

fire hazard
removal/replacement of combustibles & absorbers on outside of ship

possible ultrasonic detonation of explosives(85)
separation from field (like the crew)

high rate of energy consumption
limited usage

still-detectable ship's propulsion sound
EM [electromagnetic] propulsion(86)

distal ultrasonic/thermal signatures?

crew's inability to 'see out' to navigate, etc.
acquisition of external info by periscope extending above main part of thermal field

possible anomalous appearance of features behind the thermal field
approach observer from direction of 'unstructured' backgrounds like the open sea

ship's wake extending beyond invisibility zone
use in situations without airborne observers or simply stop moving when aircraft approach

lack of vertical invisibility-- this may be the most serious limitation
use in airborne situations without airborne observers, or camouflage the ship (the fog may help) & jam or absorb radar

thermal field structure wind susceptibility
compensation by steering of ultrasonic generators, and avoidance of use in gusty situations


Sirens are one of the best generators of powerful ultrasonics in air(87). (J. Robinson invented the siren in the late 1700's(88).) An appropriate siren consists of a toothed rotor within a ported housing, perhaps with an attached horn. The teeth of the rotor interrupt a flow of air from a compressor to form individual sound waves (Fig. III, not shown). (Note: the cross section shows only one of the siren's air feed lines.)

With a given number of rotor teeth the output frequency is controlled by setting the speed of the electric motor driving the rotor. Acoustical power output is related to air feed pressure and flow rate. This type of siren was described in a journal about four years after PX(89).

The term "flow" related by C.M. Allen(90) is a description which matches the "sonic wind" accompanying a siren's sound wave.(91)


PX can be broken down into various stages of development. Stage 1 would have involved dock-side tethered(92) test (s).

Stage 2 would have involved a sea test (93) observed from the Furuseth(94) (the Furuseth put to sea Oct. 25 (Table I) just prior to a possible apparent teleportation incident Oct. 28 (95)).

Stage 3? apparently involved the formation of a thermal field around a destroyer by the use of ultrasonic generators on two companion ships.(96) The 'observations' that have led to speculations of teleportation(97) are explainable within the setting of stage 2.

From the point of view of a participant the ship rapidly translated from Philadelphia to Norfolk (Map I, not shown), and then back again.(98) Also, there were witnesses to the brief appearance of a ship in the Norfolk area.(99) While the trip is apparently substantiated, the short duration of it is not. If the participant went unconscious (Table II) both times the thermal field was strongly developed, and the ship was under way during those times, the observed elapsed time of the trip would obviously be inaccurate.

Once could speculate that the Eldridge left Philadelphia in the morning, reached Norfolk while it was still light, and returned to Philadelphia by the next morning at almost the same time of day it left. If the participant lost track of the date during a subsequent recovery period(100) and thus did not realize he had lost a whole day, the elapsed mission time could have seemed brief.

It is likely then that the PX 'teleportation' is a misinterpretation and not an actual warp situation.


Carl M. Allen's first letter to Jessup (Table I) contains terms in quotes, indicating second hand information on the PX experience. This suggests he was not on board the Eldridge during PX operations. However, since he was apparently among the crew of the Furuseth(101) which he indicated was an observer ship(102), he may have had the opportunity to witness at least some part of Stage 2.

C.M. Allen does not seem to have had access to technical details on PX since he does not relate anything useful in this regard. He therefore cannot be confused with C.H. Allen (Dept. of Physics, Pennsylvania State College, State College, PA (Map I)), coauthor of the 1947 article on sirens.(103) The similarity of their names is interesting however.


For those interested in gravity alteration or warp technology possibilities, it would likely be of no small disappointment that such a tantalizing prospect as PX 'teleportation' would literally turn out to be a lot of hot air. A case for artificial gravity can be made however.

A possible fundamental proportionality between electric charge and gravitation at atomic scales is evident in Dirac's Large Numbers Hypothesis equations.(104, 105)

Electric field action between charges can be explained by the exchange of virtual photon field particles.(106) Virtual(?) (107) photons also compose the quantum mechanically generated Zero-Point electromagnetic radiation that pervades space(108, 109). Alteration of the Z-P EM distribution can produce actual effects (Lamb shift, Casimir effect) and it has been suggested that such an alteration by matter might explain gravity.(110) Perhaps and electric field's virtual photons interact with the Z-P's virtual(?) photon situation to produce a gravity effect.

It has been found that the period of a torque pendulum can be increased by charging it.(111) This result can be explained by an increase in the pendulum disk's moment of inertia by the addition of artificial gravitation-related virtual inertial mass with a greater radius of gyration than that of the disk. (The charge producing this gravitation should have had a greater density on the smaller radius of curvature surfaces at the periphery of the disk.)

It was also found that the pendulum's period was generally greater with positive charge, compared to negative.(112) This together with the corresponding artificial gravitational fields explains the thrust in the direction of the positive pole in high voltage DC plate capacitors (Biefield-Brown effect).(113) These empirical situations suggest the possible proportionality between charge and gravitation is applicable macroscopically.

On an astronomical scale this electric gravity may resolve the spiral galaxy rotational velocities problem that has led to the supposed requirement for huge quantities of dark matter.(114)

On a laboratory scale an effective way to produce very high voltages/charge densities may be by way of momentary electric discharges (sparks). Significant charge separations may be achieved by the short-lived formation of an electron filament surrounded by positive ions.(115)

Another phenomenon due to the action of sparks apparently involves the formation of electron clusters.(116) Considering the massive electrical activity in lightning, and electric gravity, it follows that some types of ball lightning may have a localized gravitational anomaly component. The use of momentary discharges to form a gravitational field above an object's center of mass, to reduce its weight, may have been demonstrated with Farrow's "condensing dynamo".(117)

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