Logical Thinking: Ghost Hunting Equipment
When it comes to Ghost Hunting equipment there are many different rumors and theories floating about. Some people even talk about the fabled 'Ghost Detector', however logical thinking would fault such an idea.
To detect a 'Ghost', first we must know what a ghost consists of physically and secondly how to detect such traits. Realistically these two major issues defunct the idea of being able to build a 'Ghost Detector'. The best 
approach it would seem, would be to monitor the local environment and look for irregularities. This brings me to the well known EMF meter, or Electromagnetic Field Meter, this device is used to detect and measure electromagnetic fields. Whilst there are some who believe that the EMF meter can detect ghosts, this is wildly untrue. An EMF meter detects electromagnet fields, because it is designed to. For paranormal purposes an EMF meter should only be used to find EM fields that are normally present within a location, and then monitor them for irregularities which cannot be explained. So to simplify, an investigator should look for irregularities in the EM fields of a location, not just for EM fields.
...Look for the unusual, not the obvious...
On the basis that everything in our universe, effects or is effected by something else. To detect the presence of a spirit, we need to be looking for these effects. For example to detect a car, we could look for the pressure its weight exerts to the ground or the levels of carbon monoxide in the air. Two factors which have been effected by its presence.
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