Nice aura, Dora!
Kirlian photography is a photographic technique that produces images which are interpreted by some as a supernatural aura that physically represents the 'life force', 'psychic energy' or even the 'soul' of living (or recently living) things. Such interpretations are all wrong. The image captures the light emitted from the corona discharge of objects that are subjected to high-voltage, low-current electricity.
Origin and development
The technique is named after Seymon Kirlian, a Russian amateur experimenter who discovered the phenomenon by accident in 1938. Actually, the technique had been used before Kirlian first observed it. Electrographs had been displayed as early as 1898, by Russian scientists Batholomew Navratil and Yakov Narkiewicz-Yodko. Both electricity and photography were relatively new at that time. Navratil called it electrography, and the more scientifically-minded still prefer that name, even though the principle is entirely photographic. Research was done on electrography in the decades before Kirlian's discovery. Images of leaf coronas were published by Czech scientists Pratt and Schlemmer in 1939, but the scientific community saw no particular significance in the images and took no great interest in the phenomenon. Seymon and his botanist wife, Valentina, however, were fascinated with the effect and produced images of many kinds of objects.
Kirlian photography is a contact photographic technique, so there is no actual camera with lens. The imaging system is quite simple. The main parts are a metal plate, a photosensitive medium and a glass plate, all inside a light-proof enclosure, and a source of very-high-voltage but very low current electricity (think 'static' electricity).
The light-sensitive paper or film is sandwiched between the metal plate and the glass plate. The object to be photographed is placed on top of the glass plate, which insulates the object from the electrical potential. An electric charge of thousands of volts, but very low current (amperage) is then applied in pulses to the metal plate, usually some number of times so as to build up a more interesting image. A Tesla coil is most often used to provide the electric potential. A transformer design is also possible, but potentially more dangerous. It's best to avoid those if you come across one or are considering making one. The photo medium is developed in the normal way to produce the final images. Polaroid film can also be used to obtain instant pictures.
Kirlian images, or electrographs, are produced when a light-sensitive medium such as photographic film or print paper is exposed to the light produced by a corona discharge, which is an electrical phenomenon in which electrons shoot out from the surface of a highly charged object in what is called cold electron discharge. They are often beautiful, consisting of strikingly abstract patterns and intense coloring. Generally, the outline shape of the object is discernable and the 'aura' is clearly associated with it. Lightning-like static discharges may also be recorded. No one can be blamed, really, for the temptation to interpret these mysteriously beautiful pictures as a manifestation of something spiritual or at least metaphysical.
What the images mean
While the scientists never believed the pictures to have any nonphysical aspects, their images produced much resonance in the imaginations of the lay population of the time and put the technique in the limelight of public attention. It was not until much later, in surprisingly modern times, that a strong connection between electrographs and the spiritual realm was asserted. In 1970, the books Psychic Discoveries Behind the Iron Curtain by Ostrander and Schroeder and The Kirlian Aura by Krippner and Rubin stirred up public interest in the metaphysical aspects of Kirlian images. Later, in 1979, Professor Thelma Moss of the Neuropsychiatric Institute at UCLA published The Body Electric, promoting the idea of a bio-energy that can be imaged by electrography. Other claims have been made that missing parts of leaves or even amputated limbs can be imaged by the technique. Attempts to reproduce that effect have not been successful. One also sees Kirlian images associated with acupuncture, chiropractic and various alternatives to mainstream medicine.
Today, however, only the ignorant, the hopelessly gullible or those with a most desperate need to believe will actually believe that these images are direct physical representations of the soul, ethereal body or other such imagined nonphysical aspects of a physical body. The effect itself is fully explained by science simple enough for anyone to understand, and even most New Age, alternative medicine type thinkers accept the scientific explanation. The images do indeed capture an 'energy flow' (i.e., the light produced by high-energy electrons in motion, specifically), but is that energy flow related in any way to the spiritual essence or character of an object?
Kirlian images are not like fingerprints; they vary considerably from image to image, even for the same object. Several factors are known to produce that variety. The blue-violet colors that are typical of the auras result from the excitation or ionization of nitrogen atoms in the air, and the relative humidity and the chemical composition of the air around the object greatly affect the shapes and colors of the images. As for the object being photographed, the only known variable factor that significantly affects the image is moisture content. The polarity of the electric charge, which determines which way the electrons flow, is another important factor. When alternating current is used, the frequency is an important determiner of image characteristics.
Physics vs. metaphysics
The imaginative reaction of so many minds to Kirlian photography is one little clear sign of how strong the need is in our hearts to believe that there is more to the universe than science tells us or ever can tell us. It may seem ironic that believers in metaphysics, spiritualism and other non-physical concepts try to find 'scientific' evidence in the world of physical phenomena for the non-physical things they believe in. Dualists insist that there is some kind of interface between the physical and the non-physical in the human mind. We want our ghosts to maintain our personalities and to be able to make their presence known and cause things to happen in the physical world, yet remain not of this physical world. That link is very important to counter the simple but effective argument that if there is a non-physical world that does not in any way interact with the world we know, then that other world, in effect, does not exist. That Kirlian photography is so easily and convincingly shown to be a simple physical effect is very satisfying to debunkers of bogus ideas.
Personally I believe the best approach is to be fully skeptical of claims of the paranormal or parallel worlds/dimensions and so on, while still maintaining on open mind to the possibility of having to expand our current scientific understanding of causes and effects beyond what we now accept as the limits of the physical world. The brightest minds in theoretical physics have for some time already resorted to various numbers of dimensions beyond time and the three physical dimensions that are familiar to us in attempts to explain nature with a single, consistent set of rules and entities. New Age thinkers and many plain old common sense thinkers are finding it more and more difficult to retain a sense of mystery in the face of advancing scientific understanding of the physical world, including life and intelligence. Nevertheless, it is entirely clear that Kirlian photography is nothing more than a beautiful and interesting display of our good understanding of light, chemistry and electricity.
Simple home-made 'camera'
Serious gear & images