N-ray

The so-called N rays (or N-rays) were a phenomenon described by French scientist René-Prosper Blondlot but subsequently shown to be illusory.

In 1903, Blondlot, a distinguished physicist working at the University of Nancy, perceived changes in the brightness of an electric spark in a spark gap which he attributed to a novel form of radiation, naming it the N-ray, for the University of Nancy. Blondlot, Augustin Charpontier, Arsène d'Arsonval and many others claimed to be able to detect rays emanating from most substances, including the human body. Physicists Gustave le Bon and P. Audollet and spiritualist Carl Hunter even claimed the discovery as their own, leading to a commission of the Académie des sciences to decide priority.

The "discovery" excited international interest and many physicists worked to replicate the effects. However, the notable physicists Lord Kelvin, William Crookes, Otto Lummer and Heinrich Rubens failed to do so. Following his own failure, US physicist Robert W. Wood was prevailed upon to travel to France to investigate further. His thorough investigations, published in the September 29 1904 edition of Nature, showed that these were a purely subjective phenomenon, with the scientists involved having recorded data that matched their expectations. The incident is used as a cautionary tale among scientists on the dangers of error introduced by experimenter bias. More precisely, patriotism was at the heart of this self-deception. France was defeated by the Germans in 1870, and after the major discovery by Wilhelm Röntgen of the X Ray the race was on for new discoveries.

N rays were cited as an example of pathological science by Irving Langmuir.

Blondlot still has a street named after him in downtown Nancy as the belief that he had made a major discovery persisted.

External links and references

• http://skepdic.com/blondlot.html and references therein
• 50, 100 and 150 years ago, Feb 2004 pg 14, Originally reported in Feb 1904 Scientific American