Paranormal investigators have devised a number of different theories and hypotheses about how Electromagnetic Fields (EMF) relate to paranormal activity.
Some believe that high EMF readings are evidence of paranormal activity, while others suggest the presence of high EMF fields cause paranormal activity. It is also widely believed in the medical and psychological fields that prolonged exposure to unusually high EMF fields may cause sense distortions and even hallucinations that people may mistake for paranormal activity. Regardless of the approach an investigator takes to EMF and its applications in the field, it remains a generally established rule that electro-magnetic fields are a cornerstone of paranormal investigation.
The electromagnetic field, as defined in scientific research, is a physical field produced by electrically charged objects. Electromagnetic fields are one of the four fundamental forces of nature (the others are gravitation, the weak interaction, and the strong interaction). Because an electromagnetic field is based on the existence of energy currents, it can also be created by technological devices (namely, household appliances, electronics, etc.) The way in which these charges and currents interact on a molecular level with each other and the objects around them—behavior which is based on the consumption and dissipation of energy—is what creates and defines in space the electromagnetic field.
To understand why EMF may relate to the paranormal, you have understand the fundamental role that energy plays in many of the theories behind the existence of paranormal activity. We already know that living creatures require energy to survive, even at the cellular level. There appears to be a natural dissipation and/or transference of this energy when a living thing dies. But, taking into account the law of conservation of energy, which is that energy in the universe is constant and can neither be created nor destroyed, the question remains of what exactly can or will become of the energy in a living creature when it no longer survives.
Taking this theory a step further, some researchers argue that there is no way to prove the “soul” or “personality” of a being isn’t intricately connected to the energy that, in life, was the basis on which that individual survived. Working under the assumption that it is possible for this energy to not dissipate, for there to be a glitch in the system so to speak, we begin to understand the underlying physics behind the notion that living creatures beyond their death may continue to exist as a collection of a being’s energy, minus the cellular structure it was housed in.
Working under this same assumption, when an investigator gets a high EMF measurement in an area where that field can't be attributed to a known source (e.g. A/C wires, outlets, switches, etc.), it may be argued that there is an alternate, paranormal source of energy being measured.
The parallel theory that EMF fields measuring in the high range of the spectrum are a cause of paranormal activity is based on the same principle of energy, but takes the idea of an entity’s control over its own energy one step further. Theoretically, if an entity is a collection of energy that had been previously housed in something, it stands to reason the lack of that housing could cause dissipation of much an entity’s energy – so much so that the entity cannot manipulate any of the molecules around it without help. This help could conceivably come in the form of excess energy from another source: in other words, an entity will use energy from an existing field much like a battery and add to its own energy mass, in an attempt to create enough of a molecular disturbance to be felt, heard, or seen by human senses. If there is a source of high EMF in an area; for example, an incorrectly wired circuit box, unshielded electrical wires, etc., this becomes the “battery” for an entity, the pool from which it can draw supplemental charge. (This does, however, then delve into the debate of whether spirits use A/C or D/C currents -- but that's the subject for another article.)
While the debates over spiritual energy rage on, it merits pointing out that one thing scientists are certain of is that high EMF fields have been known to cause hallucinations, which is typically why high EMF readings during a paranormal investigation need to be approached as an electrical/physiological issue before looking for the paranormal connection. While there are definite physiological links to being exposed to high EMF, even to the point of certain EMF levels being considered carcinogenic, one area of inconclusive research is what effect high EMF might have on the human brain and its ability to perceive the environment accurately.
In Mary Roach’s book Spook, we learn about the experiments that have been conducted in relation to this theory. Called by some the "Fear Cage” and by others a "Haunt Box," the reference is the same: an intentional collection of high EMF in a centralized area. Dr. Michael Persinger of the Consciousness Research Lab at Laurentian University (Ontario, Canada) has done many experiments with human subjects to find a correlation between exposing the right temporal lobe of the brain to high EMF and the subject’s subsequent feeling of a "presence." Dr. Persinger has found that, by using a soundproof chamber and a helmet covered in electro-magnets to expose that region of the brain to increased EMF, a decrease is seen in the melatonin levels in the brain. This in turn causes tiny, epileptic-like seizures, which then cause hallucinations. According to his research, over 80% of subjects reported feeling “a presence” in the locked room with them, proving that these targeted EMF fields indeed have an effect on brain chemistry and human behavioral reactions.
That being said, note that Dr. Persinger’s results do not claim the subjects “hallucinated,” but more simply that they reported a feeling of a presence. Whether or not that sensory perception is accurate is a question Dr. Persinger himself has yet to answer. In fact, he says in one of his papers, "Although these results suggest that these apparitions are an artifact of an extreme state-dependence, the possibility that they are associated with transient, altered thresholds in the ability to detect the normally indiscriminable stimuli cannot be excluded.” In other words, Dr. Persinger himself cannot determine whether the true effect of EMF on brain chemistry causes hallucinations, or if increased EMF allows us to sense an actual presence that we couldn't before. And this chicken or egg question – what comes first, the entity or the energy needed to sense it? – is what keeps EMF meters of all sizes, types, and strengths in the standard arsenal of nearly all paranormal investigators.