Kirlian photography

Kirlian photography is a method of creating images by placing an object on a photographic plate and passing high-voltage, high-frequency electrical current through it, thus producing images of coronal discharge around the object's image on the plate. It's named after Semyon Kirlian (1898-1978), a Russian electrician with a scientific bent, who (re-)discovered the effect in 1939.

In pseudoscience
Kirlian photography has little merit besides being a nice way to illustrate coronal discharge and making pretty cool pictures. Of course, that doesn't stop people trying to find un-scientific merit. Kirlian himself suggested that the images can be compared to an aura, and many New Agers seem to have run with this suggestion very literally.

Kirlian photography has been used as evidence of the existence of a "biofield". Kirlian himself had noted several changes in what he was photographing depending on conditions around him, and came up with various ideas such as bio-plasma that would link the results of his photographic technique with mood, s, and physical state. David Bowie also noted changes, specifically before and after taking cocaine. Since then, it has been associated with energy flows, meridians, and alternative medicine treatments, usually as a way of measuring, or evaluating people who claim various paranormal properties (Therapeutic touch, etc.). Changes in skin moisture and contact pressure are in fact the variables responsible for changes in the coronas, and Kirlian photography is therefore not a reliable measurement of health.