Reading about Kirlian photography many years ago, it seemed to me that the process of applying voltage to an object on a photographic plate may have an equivalent biological mechanism between the eye and the brain. Of course it is probably not so straightforward (I make no pretence to understand biology, or the electronics of kirlian photography) but fundamentally as I understand it the kirlian photograph captures images of a corona discharge. Is it this which we call the spirit? Some effects of the corona discharge may seem familiar to some:
Corona discharge is generally undesirable in:
Electric power transmission, where it causes:
Power loss
Audible noise
Electromagnetic interference
Purple glow
Ozone production
Insulation damage
Electrical components such as transformers, capacitors, electric motors and generators. Corona progressively damages the insulation inside these devices, leading to premature equipment failure. One form of attack is ozone cracking of elastomer items like O-rings.
Situations where high voltages are in use, but ozone production is to be minimised
Static electricity discharge
Kirlian photographs show a definite continuation of the energy of a leaf even after it is biologically dead, I doubt anyone has tried this with a dead body but it would be interesting to know how long the 'aura' remains, or indeed if it remains (there's no physical weight to subject it to the laws of gravity after all, well maybe about 21 grams.. The erratic nature of ball lightning would perhaps bear some resemblance to an energy field of this sort).
Forgive me for again stepping into the realm of pseudoscience here, but my proposition is that those who claim the ability to see spirits may in fact be more highly charged in some way or some part of their brain, and thus able to perceive what the kirlian photograph does. Surely the ever advancing technology of digital photography can make some sort of improvements in this field, perhaps a camera that does not require contact, or has greater sensitivity, or perhaps even a kirlian movie camera?
The 'God Helmet' episodes suggest that stimulating certain parts of the brain can increase some sense of an outside 'presence', maybe with refinement more definite visions can be made, and independently corroborated. People who take hallucinogenic drugs often report seeing the exact same phenomena, although it is generally argued that they are subject to the same influences and suggestions.
If this theory on the corona holds true then maybe a corona ring can be the latest weapon in the realm of ghostbusting? Again forgive any major faux pas here and my lack of scientific understanding in general..