Test & Measurement Handbook 2017


WE’D like to think that the average viewer who tunes into a TV show on the SciFy channel called Ghost Hunters might get a laugh out watching investigators prowl around places that are reported to be haunted. But the show participants seem to be completely serious and unconcerned about the fact they find essentially nothing week after week.

Our own impression of the show is that the producers are quite lucky that average TV viewers don’t understand the workings of either gauss meters or RF power meters.

Unsurprisingly, not much happens on Ghost Hunters. Investigators set up electronic equipment in what are supposedly paranormal hotspots. They then spend several hours taking electromagnetic field and temperature readings, recording audio, and filming with digital video cameras.

Perhaps to make up for the lack of action, show investigators have tended toward instrumentation that provides more audiovisual interest than just numbers on a display. They have used an EMF meter on which LEDs, rather than a number on an LCD, give a measure of field strength. They’ve also employed a custom-made geophone (normally used for detecting seismic disturbances) which flashes LEDs in proportion to the intensity of vibrations. Another EMF detector they use buzzes when it detects an electromagnetic field.

The fact that Ghost Hunters uses EMF detectors in any capacity might lead the average viewer to think that “ghosts” are some how expected to generate electromagnetic energy. But a better grasp of the origin of this idea could pour even more cold water on the proceedings in the show.

The connection between ghostly appearances and EMFs was theorized by Michael Persinger, a neuroscientist at Laurentian University in Canada. In one of his studies he describes the experiences of a teenager who in 1996 claimed to get nocturnal visits from the Holy Spirit. Persinger’s group found that an electric clock near the 17-year-old’s bed generated electromagnetic pulses with waveforms resembling those found to trigger epileptic seizures. Removing the clock stopped the girl’s visions. Persinger theorized that the clock, in combination
with mild brain damage that the girl had sustained at birth, were likely contributing to the perceived ghostly experiences.

Persinger has done a lot of research on how electromagnetic stimulation of the frontal lobes of the brain can induce feelings of a “sensed presence.” However, the field levels involved must be pretty high and are usually generated by having a subject wear special headgear sometimes dubbed a God helmet. Experiments with lower levels of EM stimulation, as might arise when someone wanders around a room, have been somewhat controversial. Research groups have mostly been unable to see any “ghostly” hallucinations under such circumstances though Persinger claims some success in this area.

Getting back to Ghost Hunters, investigators on the show seem to act as though fluctuations on their gauss meters may indicate a ghostly presence. If Persinger is correct, a noteworthy reading on a gauss meter is more likely an indication of hallucinations rather than any spiritual activity.Lee Teschler

And there’s no reason spirit hunters on the show need special instruments to see magnetic fields. There are some pretty nifty apps for the iPhone that will use the phone’s Hall sensors to read out not only the magnitude but also the direction of magnetic fields on the order of 25 to 65 mT range as created by the earth.

Of course, waving around an iPhone rather than a gauss meter probably doesn’t look particularly convincing if you are playing to an audience hoping to see evidence of ghosts.

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