Terence Hines - Pseudoscience and the Paranormal

In the course of further investigation, it was found that the sun, flames, and incandescent objects were all sources of N rays. Another French investigator, Auguste Charpentier, found that the human nervous system emitted N rays, and this finding was soon “confirmed” in Blondlot’s laboratory. Further, when a portion of the nervous system was active, that portion was said to emit more N rays. Blondlot also discovered “secondary” sources of N rays. These were sources that absorbed N rays and then reemitted them. The fluids of the human eye were alleged to be such secondary sources and, amazingly, when the eye was exposed to N rays, it became more sensitive to dim illumination. Text that could not ordinarily be read in dim light could be read after the eye was exposed to N rays.

Here, then, was an important new phenomenon, confirmed by dozens of independent studies in many different laboratories, many of the studies conducted by well-known and highly respected scientists.

But other physicists, especially those working outside France, were skeptical about the existence of N rays. They objected to the conclusions of Blondlot and others who based their results on subjective judgments of brightness. Such judgments, which are liable to be influenced by the observer’s beliefs, are poor sources of data. One experiment allegedly showing that N rays increased visual sensitivity was faulted as being due to nothing more than dark adaptation—the phenomenon that accounts for the increase in ability to see in a dark room the longer one spends in such a room. More devastating to the claims about N rays was the failure of other physicists outside France to repeat Blondlot’s results. These failures were most striking when objective as opposed to subjective measures of brightness were used. Nye (1980) chronicles the numerous failures to replicate Blondlot’s results in the few years following his initial report.

One of the most telling pieces of evidence against the existence of N rays came in 1904, when American physicist Robert W. Wood decided to visit Blondlot’s laboratory to see for himself whether Blondlot’s experiments were valid. Wood was an extraordinary man, with many interests outside physics (Seabrook 1941). One of his interests was exposing fraudulent spiritualist mediums; Wood’s experiences in this endeavor must have helped him when he came to evaluate Blondlot’s N-ray experiments.

Blondlot had found that N rays were blocked by lead. Wood observed demonstrations of N-ray effects in Blondlot’s laboratory and concluded, as had other critics, that the reported changes in brightness that Blondlot used to argue for the reality of N rays were figments of Blondlot’s imagination and a result of his desire to validate the existence of N rays. N-ray experiments had to be carried out in a darkened laboratory so the changes in brightness due to the rays’ presence could be observed. This gave Wood an opportunity to make several observations that proved Blondlot’s judgments of brightness changes were a function of his beliefs, and not of the presence or absence of N rays. In one experiment, Wood was to block an N-ray source by inserting a sheet of lead between the source and a card with luminous paint on it. Blondlot, acting as observer, made judgments about the paint’s brightness and, therefore, about the presence or absence of N rays. Without telling Blondlot, Wood changed the experiment in one slight but vitally important way. He would indicate to Blondlot that the lead sheet was blocking the N-ray source when it really wasn’t, and vice versa. If N rays really existed, Blondlot’s judgments of the brightness of the luminous paint should be a function of whether the lead screen really was between the card and the N-ray source and should have had no relationship to whether or not he believed the sheet was blocking the source. In fact, Wood found that Blondlot’s judgments depended on whether he believed the screen to be present or not. For example, if he believed the screen was present (blocking N rays), but it wasn’t, he reported the paint to be less luminous. If he was told the screen was not present (allowing N rays to pass), but it really was, he reported the paint to be more luminous.

Similarly, in two other situations, Wood showed Blondlot’s subjective brightness judgments to be a function of his belief. Blondlot had claimed that an aluminum prism would produce a spectrum of N rays of different wavelengths, just as a glass prism produces a spectrum of visible light of different wavelengths. Wood found he could remove the aluminum prism from the path of the N rays without interfering with Blondlot’s ability to see the N-ray spectrum. Later, when Blondlot’s laboratory assistant became suspicious of Wood, Wood pretended to move the prism, while leaving it in place. This caused the assistant to report that the N-ray spectrum was not present. Finally, Wood performed a similar substitution in an experiment designed to show that N rays increased visual sensitivity in dim light. An N-ray source was placed near a subject’s eyes. The “subject of the experiment assured Wood that the hands of a clock, which were normally not clearly visible to him, became brighter and much more distinct” (Klotz 1980, p. 174) when the N-ray source was held near. Wood then replaced the N-ray source with a similarly shaped piece of wood, a substance that was not an N-ray source. Nonetheless, as long as the subject was unaware of the switch, he continued to report that objects were brighter and more distinct when the piece of wood, which he believed to be an N-ray source, was close to his eyes.

Wood’s report, published in the British journal Nature in 1904 (reprinted with a short commentary by Hines 1996), along with the failures of other laboratories to verify the existence of N rays, led to the conclusion that N rays do not exist. No further papers appeared on the topic after about 1907. Only Blondlot, convinced until the end that N rays were real, pursued his research on the topic until he died in 1930.

At the height of the debate over the existence of N rays, proponents adopted a nonfalsifiable hypothesis to account for critics’ inability to observe the rays: The critics’ eyes weren’t sensitive enough. When Wood initially told Blondlot that he couldn’t see any brightness difference on a screen when the rays were or were not present, he was told “that was because my eyes were not sensitive enough, so that proved nothing” (Seabrook 1941, p. 238). Years later, one of the early proponents of N-rays made a similar point: “If an observer (who is not convinced) sees nothing, you conclude that he does not have sensitive eyes” (Becquerel 1934, cited in Nye 1980, p. 153).

It is vital to note that Blondlot and the other proponents of N rays were not lying when they reported that they saw a brighter spark or luminous screen when they believed that N rays were present. Sparks and luminous screens vary in brightness from moment to moment for several reasons. Random changes in brightness that confirm an observer’s belief are much more likely to be noted than those that go against the belief. Numerous similar instances where a belief can profoundly change the way in which someone perceives a stimulus will be noted throughout this book.

The case of N rays also illustrates how science handles the burden of proof. (Compare this to the discussion of academic studies of ESP in chapter 4.) Assume that someone wished to argue, today, that N rays really do exist. To bolster the case, he goes back to the physics journals of 1903–1907 and assembles all the papers that argued that N rays are real. The proponent then challenges the skeptic to explain in detail what was wrong in each of the published papers favorable to the existence of N rays. Could the skeptic meet this challenge? Certainly not—there is simply not sufficient detail in the papers to pinpoint precisely what led the author to mistakenly conclude that N rays existed.