A ghost is a dark matter-composed plasma-based life form that originally existed in symbiosis with a human body, but decoupled from that physical form upon its death.
Dark matter consists largely of a plasma of very high energy non-standard particles (sometimes of a different parity) - or "dark plasma". Non-standard particles are particles that are outside the physicists' Standard Model and which are included in dark matter - matter which is six times more prevalent in the known universe than ordinary matter. Two different substrates, plasma and carbon, gave rise to life. Plasma life forms, in fact, spurred development of organic carbon-based life on Earth.
Meteorites, asteroids and comets, containing both the dark and visible building blocks of life fell into habitable zones and generated the first single-celled and later multi-cellular life-forms which developed both ordinary and dark matter "bioplasma" bodies that were coupled to each other. Hence, when life began on Earth, plasma life forms were forming symbiotic relationships with these primordial carbon-based organisms.
Practically all carbon-based life forms today, including homo sapiens, had symbiotic relationships with plasma-based life forms. Hominids are the products of a symbiogenesis between a carbon-based and plasma-based life form. Unlike other animals, however, carbon-based hominids were able to utilize the alternative cognitive-sensory systems of their plasma-based symbiotic partners. Their unique brains allowed them to activate the higher energy bioplasma bodies that co-evolved with the carbon-based body without necessarily having any conscious awareness that they were accessing a different cognitive system. Relationships developed between the lower energy carbon-based bodies of hominids and the higher energy bioplasma bodies and were sustained for several millions of years up to the present.
When certain brain circuits in the biochemical brain (particularly in the parietal and temporal lobes) are disabled, the locus of consciousness from the carbon-based body of a human was transferred to the plasma-based body. During REM sleep the carbon-based body processes information from the bioplasma body. The plasma-based body is connected with, and an extension of, the biological body. Our brains form neuronal patterns from our experience. In a similar way our bioplasma ‘brain’ also form patterns from our experience. The bio-plasma ‘brain’ records the essence of experience and therefore the essence of personality.
The bioplasma body originates and usually dies together with physical-biochemical body or a short time thereafter. This is not surprising as the age of this bioplasma body approximates the carbon-based body since both bodies originates at about the same time in a particular lifetime. However, in certain cases, for example accidental death, the still healthy and undamaged bioplasma body decouples from the carbon-based body. These bioplasma life forms continue to exist as entities commonly referred to as "ghosts."
As bioplasma bodies, ghosts generate electromagnetic fields and radiate electromagnetic waves. Ghosts can glow in the dark, radiate heat, light and other electromagnetic waves that can be measured by scientific instruments like radar or even infra-red cameras when ordinary matter condenses around them. Embedded in these bioplasma bodies are "plasma antennae" which can tune-in and receive electromagnetic waves generated by other bioplasma bodies. The bodies of ghosts can sometimes be molded by expectations which radiate out from our own bioplasma bodies in the form of electromagnetic waves and are received by them through their embedded antennae. The nearer they come to a person the better they are able to tune-in to the thought waves (i.e. electromagnetic waves which are modulated by your thoughts) that person is radiating out from their bioplasma body.
By switching-off the relevant (and specific) brain circuits, a person may transfer his or her locus of consciousness to their bioplasma body which has the necessary sensory apparatus to be able to view these plasma-based life forms known as ghosts. Sightings of ghosts often occur at night - when a person is sleepy. This provides the ideal conditions for a person to go into a meditative state and effect a transfer of consciousness to the bioplasma body with the different cognitive-sensory systems. The relevant brain circuits may be switched-off physically through surgery, accidents like brain injuries, transcranial magnetic stimulation and ambient electromagnetic fields which simulates brain lesions; chemically through psychoactive drugs; psychologically through meditation or hypnosis or during sleep. Some people are born with these brain circuits inactive - congenital "mediums."