The "Geller effect" is the abnormal deformation of metal (and possibly other) objects first brought to public notice by the Israeli entertainer Uri Geller. As demonstrated by Geller, a spoon is gently stroked at its narrowest portion; it suddenly becomes as if plastic there to such an extent that it might even break in two pieces. The phenomenon is abnormal in that the amount of pressure being applied ap pears far too small to cause such distortion or fracture. As is true of all other paranormal phenomena, validation of the Geller effect is non-triviaL Many cases have been reported in the media of the effect's being caused either by Geller or by other subjects who have since come forward. It is necessary to go beyond such reports, both to validate and to probe the effect further. The next level of investigation is that of close personal observation. This is still not acceptable to some, so care must be taken to exclude fraud of every conceivable sort.
Five general types of fraud might produce Geller-type phenomena; each can be and, in fact, has been prevented in various investigations in the following ways. The simplest kind of fraud is the application of unnoticed mechanical force. This can be prevented by placing the object in a sealed con tainer or otherwise making direct contact with the object im possible. If contact is found to be necessary the pressure applied can be measured by a pressure balance or a piezo electric pressure transducer. Additionally, the contact required for the phenomena to occur is often inappropriate to produce them mechanically (i. e., stroking the upper surface of a metal strip which then bends upward against the pres sure). The second type of fraud is replacement of the object with a duplicate which has already been bent. This can be prevented by marking the object, by fastening it to the surface, or by using an object so unusual that it is extremely difficult to duplicate.
Use of chemicals constitutes the third type of fraud. Aside from prevention of direct contact with the object, one can guard against this by observing and analyzing the surface of the object after it has been bent. Characteristic cracks arise from chemicals causing metal distortion. This is an unlikely explanation for the many cases in which the subjects are children, since such chemicals would be inaccessible to them. The fourth type of fraud is application of heat, such as by a laser beam from a concealed source. One can check on this by measuring the temperature of the specimen being distorted, for example by thermocouple. Again, child sub jects are unlikely to have access to high-powered lasers. The final source of fraud is that produced by the experiment er himself, and the only protection against it is a lack of bias on the experimenter's part.
Two specific cases appeared to avoid these methods of trickery. In one of these Geller stroked the upper sur face of a strip of metal which was screwed down to the top of a letter balance. The pressure he was applying could be monitored directly by the balance dial (accurate to 7 grams) as well as measured automatically by a shielded metal plate placed vertically above the metal top of the balance and connected to a quadrant electrometer (sensitive to 5 oz.). A bending of 10° occurred in one session, which I closely ob served, during which no pressure greater than 10 grams was applied. In any case the bend was upwards. This experiment is presently being repeated with videotape. A videotape was obtained of a spoon bending on its own, though I was not present during the session. The subject was a 16-year-old boy. The other case avoiding fraud was that of a metal strip bent in a sealed tube. This was not done in my pres ence, but the seal was completely undisturbed, small marks on it being unchanged. Criticism of the sealing procedure has not proven adequate, so that this case appears a good one for validation. However, none of the above cases can be regarded as absolutely fraud proof.
There have been attempts to discover various features of the Geller effect by measuring several physical parame ters, including temperature change, ultraviolet and infrared emission, magnetic and electrical fields, current flow, changes in grain size of the metal, presence of delayed bending and range of material of the object. Some provocative data are beginning to be obtained. Enough precautions were taken dur ing these experiments to enable one to regard the results seriously. The most interesting feature discovered was that most bending occurred with non-annealed specimens, as if the internal stress energy (dislocation energy) were being utilized. Another aspect is that objects have been observed to bend even hours after initial contact by a subject.
Various theoretical explanations for the Geller effect could be considered, the most immediate being that it is caused by electromagnetism. Electromagnetic detectors have been used to test this hypothesis, and attempts have been made to cause metal objects or crystals to bend or break by exposing them to strong fields of a range of frequencies. No success has yet been obtained.