Perhaps 'manifestation' would be a better word than 'materialization'. I don't claim to understand the whole process but it requires the use and manipulation of the energy from the local environment. Here is an explanation from someone who seems to know their stuff...Can you define what you mean by "materialization"? What kind of "material" is involved here? If there is a "material" involved here it might be possible to propose some kind of testable hypothesis.
MANIFESTATIONS
Depending upon the strength and amount of energy a spirit has gathered as well as how active the spirit is, a spirit can manifest itself into different types of apparitions. The first thing is to learn how a spirit can absorb energy in order to manifest itself. Spirits try to manifest themselves for many reasons, i.e. they don’t realize they are dead and are trying to communicate with the living for help. These are all forms of constructive energy:
There are several ways a spirit can absorb energy to manifest itself, the first way is to absorb the heat in a particular area. Heat is nothing more than the resonation of molecules, the faster the molecules move; the hotter the area is. Well, when the spirit absorbs this kinetic energy, the end result is the area being colder than the ambient temperature; hence, a cold spot is formed! Cold spots are an easy way to detect paranormal activity! Cold spots can be measured with an infrared thermometer, seen with a thermal imaging camera, and felt with bare skin. They typically last a second or two and can be measured as a drastic temperature change.
An other way that spirits can absorb energy is by feeding upon ionized air molecules. Typically this happens during a thunder storm when the frequent lightning strikes cause air molecules to ionize. Spirits then feed off this energy and manifest themselves a lot more frequently than during calm weather. I know this is true because I have gone ghost hunting during a thunderstorm and have gotten far more activity on my EMF meter. I would like to stress that the lightning does NOT cause my EMF meter (cell sensor) to spike, and I get quick spikes in between lightning strikes which I presume to be supernatural. My Trifield meter, on the other hand, is sensitive to this and WILL detect the lightning, but this is because it is a natural electromagnetic field detector. It is important to make sure that an EMF meter doesn’t detect lightning if you are trying to detect spirits. Mainly natural EM meters will detect lightning, static electricity, etc.
Natural EM fields can be generated due to the earth’s magnetic field. These geomagnetic fields also can be used by spirits to help them manifest themselves.
The next, creepiest, way that a spirit can absorb energy is by absorbing it out of the living! They can’t kill you or anything of the sort but you may feel physically exhausted. This happened to me a couple of times where, for no apparent reason, I just felt physically exhausted. In other words, I had felt like I had just run a mile! The reason is simple, we as living beings have energy that we can simply replenish by eating food; thus, they partake in this and leave us with a feeling of exhaustion.
Finally, spirits love to suck the energy out of the batteries in electronic devices. This phenomenon can easily be noticed when you know that your batteries are full and then they suddenly become depleted. However, you must realize that cold weather kills alkaline batteries and old batteries tend to lose their capacity of holding a charge. With this in mind, you can be able to detect this annoying phenomenon when your electronic device suddenly fails because the battery has no charge.