Ghost Hunting
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[edit] Definition
Ghost Hunting refers to the actions of paranormal investigators searching for evidence of ghosts, particularly in haunted houses.
Ghosts are disembodied spirits which are usually claimed to be the souls of the dead. Usually it is claimed that the soul is supposed to depart to another realm but for some reason the spirit in question is unable to do so.
[edit] Ghost Hunting Techniques
[edit] Photographs
Of course, the holy grail of ghost hunting is to come back with a picture of one. As no one has yet done so (at least, that didn't turn out to be a hoax), ghost hunters have to rely on, well, less convincing pictures.
Since very few ghost hunters are trained, experienced photographers, the pictures they take can have artifacts which are misinterpreted as spirits. Some of these pictures are nothing more than orbs. Others are noise in the picture that looks like a human form due to pareidolia. Many other photographic effects can be culprits.
[edit] Audible Sounds
One of the most frequent aspects of reports of hauntings deals with sounds, either the sounds of footsteps or of moaning when there is no one around. Ghost hunters set up audio equipment and go through hours of recordings trying to hear evidence of the spirit.
The sound of footsteps can be explained easily as the creaking of wooden boards or studs in the house. They're usually heard as someone lies in bed ready to go to sleep; in such an occasion, the sense of hearing is often heightened. Also, there are few other sounds in the house at that time to drown out the creaking. This allows the person to hear very clearly the creaks and pops that occur as the outside temperature cools and the wood in the house changes shape.
A similar explanation exists for the moaning, although in this case it would be due to the warping of individual boards, particularly long, thin boards used in walls and floors. In addition to the above aspects, the shape of most haunted houses, being either multiple stories or with an attic, can amplify and reverberate the sound, making it sound even more like a human moaning.
Of course, when ghost hunters pick up these sounds they are almost always considered as proof of a haunting. Even when they don't, they can pick up small noises, such as that of the wind or of small animals, and when they use their equipment to amplify and enhance the sound it often sounds like whispering or chattering. In reality, it is their own brains interpreting the sounds to try to find familiar patterns, just like with backward masking. Actual distinguishable voices can also be picked up due to Electronic Voice Phenomenon.
[edit] Low-Frequency Sounds
Some ghost hunters use audio detectors to detect sounds below 20Hz, which is below the range of human hearing. They claim that these sounds occur most frequently where people report spiritual activity.
In reality, these low-frequency sound waves could be caused by nothing more than the wind moving over a wall or between cracks. It has been scientifically established that these low-frequency sounds can cause sweating even in the cold, shivering, breathlessness, and even feelings of fear or paranoia. This completely explains the link between haunting reports and the waves, as these feelings are often associated with the presence of a ghost.
[edit] Electro-Magnetic Fields
Ghost hunters often use equipment capable of detecting and measuring Electro-Magnetic Fields (EMF), claiming that this is more evidence of spiritual activity. Also related to this is the common use of a compass to detect anomalies.
The first problem is that there is no link between EMF and ghosts. How would ghosts produce or affect EMF in the first place? The ghost hunters have no answer for this.
Second, there are all sorts of other explanations for variances in EMF. The most common is the electrical wiring in the building. Nearby high-voltage power lines can also be a cause. There are also natural variances in the Earth's magnetic field. The ghost hunters do little to try to account for all of the other explanations, although sometimes they make a token attempt.
In an episode of Mystery Hunters, 19-year-old Christina Broccolini tries to verify a claim by ghost hunters that a room of a house is haunted because of a spike in EMF. The scientist who accompanies her measures the same spike, but when Christina goes downstairs and shuts off the heat, the EMF levels drop, only to come back up again when she turns the heat back on.
[edit] Infrared
Ghost hunters also like to use infrared cameras to search for evidence. Here, the infrared cameras used are usually thermal-infrared, rather than the near-infrared cameras used for some specialized kinds of night filming. All objects give off radiation, called blackbody radiation, whose intensity and peak frequency is based on the object's surface temperature. Objects in the usual temperature ranges that people are likely to encounter on a day-to-day basis -- rocks, houses, cars, other people -- will give off blackbody radiation that peaks in the thermal-infrared range. It stands to reason that a ghost, like everything else in the universe, will expend a certain amount of heat, and thus should be detectable by a thermal-infrared camera.
The problem with this is exactly the same as the claim: all objects at normal temperatures produce light in the thermal-infrared range. The more heat an object produces, the more it will show up on an infrared camera. This is how rescue workers can use infrared to search for survivors in rubble: their body heat is greater than that of the rubble that surrounds them. But the difference is only in intensity; a hot stove will show up much more clearly than even a person because of the greater amount of heat output. Infrared light does not discriminate on the basis of living vs. nonliving entities.
Like EMF, heat can vary even in a single room. The body heat of the inhabitants can cause the high-traffic areas to show more clearly. The wall opposite a window where the sun shines through can likewise be heated and show up, even after nightfall. The heating and cooling system in the building can also be a culprit. There are many reasons for variances in heat, and these variances will all show up with an infrared camera. It is true that many times these variances will show up in the shape of a human face or figure, but this is mostly due to pareidolia.
