The story of French physicist Rene Prosper Blondlot is a story of self-deception among scientists. Because many people have the misguided notion that science is supposed to be infallible and discover absolutely certain truths, these same people look at the Blondlot episode in the history of science as a vindication of their excessive skepticism towards science. People such as Charles Fort and the Forteans relish accounts such as this one regarding Blondlot, because it is a story of a famous scientist making a great error. However, if one properly understands science and scientists, the Blondlot episode indicates little more than the fallibility of scientists and science.
So, what did Blondlot do? He claimed to have discovered a new ray, which he called the N-ray, after Nancy, the name of the town and the university where he lived and worked. Not only that, but dozens of other scientists confirmed the existence of N-rays in their own laboratories. The problem is that N-rays don't exist. How could so many scientists be wrong? They deceived themselves into thinking they were seeing something when in fact they were not. They saw what they wanted to see with their instruments, not what was actually there (or, in this case, what was not there).
N-rays were allegedly radiation exhibiting impossible properties, emitted by all substances except green wood and certain treated metals. In 1903, Blondlot claimed he had generated N-rays by a hot wire inside an iron tube. The rays were allegedly detected by a calcium sulfide thread which glowed slightly in the dark when the alleged rays were refracted through a 60 degree angle prism of aluminum. According to Blondlot, a narrow stream of N-rays was refracted through the prism and produced a spectrum on a field. The N-rays were reported to be invisible, except when viewed when they hit the treated thread. Blondlot moved the thread across the gap where the N-rays were thought to come through and when the thread was illuminated it was said to be due to N-rays.
Nature magazine was skeptical of Blondlot's claims about N-rays since laboratories in England and Germany had not been able to replicate Blondlot's results. So, Nature sent American physicist Robert W. Wood of Johns Hopkins University to investigate Blondot's discovery. Wood suspected that N-rays were a delusion. He pulled a dirty trick on Blondlot by removing the prism from the N-ray detection device. Without the prism the machine couldn't work. Yet, when Blondlot's assistant conducted the next experiment he found N-rays. Wood then tried to surreptitiously replace the prism but the assistant saw him and thought he was removing the prism. The next time he tried the experiment, the assistant swore he could not see any N-rays. But he should have, since the equipment was in full working order. So, he had seen N-rays when he shouldn't have and didn't see them when he should have. Why? Because N-rays don't exist. What did he and the others who verified Blondlot's N-ray experiments see, then? They saw what they wanted to see. They deceived themselves into seeing what did not exist.
Were they stupid? No, I don't think so. The issue isn't one of intelligence or stupidity. It is one of psychology, the psychology of perception. Blondlot and his followers suffered "from self-induced visual hallucinations." [Gardner, Fads and Fallacies, p. 345 n. 1] According to Martin Gardner, Wood's exposure of Blondlot led to the French scientist's madness and death. [ibid.]
What is the lesson from the Blondlot episode? James Randi writes
Yet science does not always learn from these mistakes. Visiting Nancy recently and speaking on the subject of pseudoscience, I discussed this example and though I was in the city that gave the name to N-rays, no one in the audience had ever heard of them, or of Blondlot, not even the professors from the University of Nancy!
[ James Randi at Cal Tech]
Well, I think the fact that Blondlot is not remembered at Nancy ought to be taken as a sign that science does learn from its mistakes. If Blondlot were a pseudoscientist and Randi visited the University of Pseudoscience, it would be highly probable that the modern professors and students in the Department of the Occult and Paranormal would look upon Blondlot as a hero and Wood's expose as diabolical, unfair, and typical of the prejudice of scientists against their holy work, etc. No, I think the fact that Blondlot is not considered a prophet in his homeland is a healthy sign that although scientists often make errors, even big ones, other scientists will uncover the errors and get science back on the right path to understanding nature. Those who think that science should be infallible or not be at all have no clue as to the nature of science.
See related entries on Charles Fort and the Forteans, Piltdown Man and pseudoscience.
further reading
Asimov, Isaac, "The Radiation That Wasn't," The Magazine of Fantasy and Science Fiction, March, 1988; also in Out of the Everywhere (1990).