N-rays aren't real. Consider this an abject lesson in bad science. The N in N-rays stands for the Nancy-Universite in Lorraine France. In 1903, French physicist Rene-Prosper Blondlot was trying to polarize X-Rays. He detected changes in the brightness of the spark in a spark gap placed in an X-ray beam. He took photographs to document the phenomena. He attributed it as a novel and new form of radiation.
You know already that he was wrong. But in the context of the time, it seemed completely plausible. Cathode rays were only first observed in 1869 by Johann Hittorf. Victor Schumann only discovered ultraviolet radiation in 1893. X-rays themselves had only been discovered in 1895 by Wilhelm Rontgen. Henri Becquerel discovered radioactivity in 1896. J.J. Thompson only discovered electrons in 1897. [LINK] Nonetheless, some scientists were able to confirm his findings, others could not.
The experiment was carried out in the dark or low light. Blondlot generated N-rays using an electrified wire inside an iron tube. This is based on Fleming's method for measuring high-frequency currents and electromagnetic waves. He used a Ruhmkorff induction coil, similar to Adolf Slaby's method for measuring spark resistance. (above) The N-rays were then detected by their effect on a calcium sulfide thread that glowed slightly in the dark when the rays were refracted through a 60-degree angle prism of aluminum. This wasn't an optical prism like the one that refracts light into rainbows on your grandmothers porch. This was a reflective aluminum wedge with a 2mm gap. A narrow stream of N-rays were refracted through the prism. Blondlot moved the thread across the gap to detect them.
To begin with, his method of detection was imperfect. Calcium sulfide thread was being used like a filament, as in a Crooks tube, or cathode tube... except it wasn't in a vacuum. But the idea of a cathode is that he increased random heat motion of the filament atoms knocks electrons off atoms on the surface of the filament. In a cathode tube the electrons have a negative charge and are repelled by the cathode and attracted to the anode. This excites the atoms of the glass and causing them to fluoresce. In those early experiments by J.J. Thompson and Eugen Goldstein objects placed in front of the cathode could cast a shadow on the wall. Blondlot was trying to replicate this but without a vacuum tube. It was something that even Michael Faraday would have taken to task a century earlier.
Blondlot was debunked by physicist Robert W. Wood. While observing Blondlot replicate the experiment he surreptitiously removed the prism. Despite it's absence Blondlot continued to detect N-rays. They had been a figment of Blondlot's imagination. The book Flash of the Cathode Rays by Per F. Dahl covers this event in great detail.
Thursday, June 11, 2015
Subscribe to:
Post Comments (Atom)
No comments:
Post a Comment