1. Spirits of the Deceased
Common culture dictates that apparitions are human spirits separated from their bodies by death. Surprisingly, it seems Einstein considered this a true possibility: “If energy cannot be created or destroyed but only change form, what happens to our body’s energy when we die? Could that somehow be manifested as a ghost?” In 1907, Dr. Duncan McDougall attempted to prove that at the moment of death, the soul leaves the human body and the body thus weighs less – 21 grams to be exact. His work was later discredited, but has since inspired other researchers to determine the soul’s weight and all resulted in some measurable weight loss after death, although results varied greatly. However, this does seem to imply that something that leaves the body following death – could this be the human soul, that for unknown reasons, lingers here on Earth?

2. Neutrinos
Neutrinos are weak, electrically neutral particles with the ability to pass through any form of matter. They are created by radioactive decay. If paranormal beings were made up of neutrinos, this would explain their ability to pass through objects. However, if this were true they would be silent and invisible to the naked eye. It’s possible that ghosts are made of neutrinos, but under the right conditions these neutrinos are charged and thus become audible and visible. This could explain why supernatural activity is more likely during solar storms and during heightened geomagnetic activity.

3. Infrasound Resonation
Some sounds emitted occur at too low a frequency for the human ear to fully process. These infrasound waves occur anywhere between one to twenty Hertz. They are so quiet that you don’t actually hear them, but your ears can still sense them. Your brain can’t zero in on the source so your mind becomes confused, causing fear, dread, panic, nausea, anxiety, and chills. At 18.9 Hz, the human eyeball will actually vibrate just enough to create optical illusions. This accounts for at least some reported sightings. In 1998 at Coventry University, Vic Tandy discovered infrasound resonation to be the source of ghostly apparitions and feelings of fear. A fan emitting a low frequency sound wave of 18.9 HZ was the culprit, and Tandy published his findings in the Journal of the Society for Physical Research.

4. Geomagnetic Waves
Robert Schoch, a professor at Boston University, is currently researching the relationship between brain waves and geomagnetic waves. His theory is that the mind’s emotional states can travel along the low frequency wavelengths found naturally in Earth’s geomagnetic field. In this way, they can be transferred between people and result in apparitions. Although this explanation may seem far-fetched, his laboratory has compiled evidence that a positive correlation exists between apparition sightings and geomagnetic flux patterns.

5. Electrical Stimulation of the Mind
Recently, researchers in Switzerland published a paper in the journal Nature. These doctors electrically stimulated the left temporoparietal junction of the patient’s brain to treat epilepsy. This is the area of the brain responsible for recognition of consciousness – it allows us to differentiate between ourselves and other people. The result was that the patient described a ‘shadow person,’ closely following her every move. Her mind was unable to detect the break in her consciousness, and instead sensed a strange presence.Summary
Although we currently have no concrete answers as to what exactly ghosts are, or if they even exist, the possibility still remains. There is much in the universe that we still don’t know. Every scientific fact we now know to be true was just an unproven theory faced with skeptical opponents. Throughout history we have consistently developed new technology and improved our scientific methods of detection. There is no telling what we might find in the years to come.

Q: Is this a real science?
A: Yes, it is. 
There are several scientific organizations and laboratories around the world investigating this phenomenon. Several are affiliated with or run by respectable universities and conduct experiments using the scientific method and advanced technology like Geiger counters, infrared cameras, ion detectors, digital video/ audio recorders, and Electromagnetic Field (EMF) to detect evidence of any abnormal presence. 

Q: Where can I find out more?
A: The American Paranormal Research Association (http://apraparanormal.com/), the Paranormal Research Organization (http://www.paranormal-research.org/), and the International Paranormal Reporting Group (http://www.iprgc.com/) are great places to start. 

Q: What universities have supported experiments and research in this field?
A: Stanford University (1970s-1980s), Duke University (1930s-1960s), Princeton University (1970s-2000s), Harvard University (1990s-2000s), University of Virginia (1960s-present), University of Arizona (2000s-present), University of California (1960s-1970s), and Cornell University (2000s), as well as several others worldwide.

Throughout history, imagery attached to ghosts is of shadowy, vaporous figures. Mysterious ghosts and phantoms reportedly haunt graveyards, misted moors, famous hotels, hospitals and prisons and castles. Spirits may possess good or evil auras.

Historical Ghost Sightings
In southeastern Ireland, Wilton Castle stands with only fire-scarred walls remaining. Ravaged by fire in the 1920s, this was the stately home of the prominent Alcock family since the early seventeenth century.

It’s believed several spirits reside within Wilton Castle walls. The strangest story about Wilton Castle is of a neighbor, Archibald Jacob, magistrate and captain of the local militia during the 1798 rebellion of the Irish against Britain.Jacob flogged and tortured many people in the parish. While returning home from a Wilton Castle ball one night in 1836, he was killed when he fell from his horse. For years, his ghost haunted the scene of his death and the castle.According to the story, a Catholic priest was summoned to perform an exorcism. When the priest made the sign of the cross and Archibald Jacob’s ghost appeared in the fireplace and subsequently disappeared in a cloud of smoke.Classic vs. Modern Sightings
Spectral hunting and paranormal research have always been subject to criticism and skepticism. The classic spectral image depends on the era in which the specter emanates. Although white-garbed spirits are the centuries-old popular image, naked spirits have been reported in a well-known Scandinavian story, where a scantily dressed man returns to his village after his death. The Japanese image of specters is clothed and often disheveled and bloody.Locations of Hauntings
The traditional locations of hauntings have been Scotland, Ireland, England and Germany. Hauntings of the early 1600s have also been reported in New England in the USA. The locations of hauntings have been reported in cemeteries and ancient Native American burial grounds. Military battle grounds of the Revolutionary and Civil Wars are reportedly haunted by unrested souls who died in battle.

Cultural Burial Rituals
Certain aboriginal cultures like Eskimos in the Bearing Sea, the Dogon people of West Africa, Siberian Chukchi and Kwearriburra in Queensland, Australia practice burial rituals to ward off the return of the dead who walk the earth restlessly. Within a culture, there are practices that transcend time and afford each culture a specific embodiment of understanding basic natural and spiritual events modern day people accept with skepticism.

Buildings, War and Mysterious Events
Old, empty buildings often evoke images in windows, in attics, basements, across expanses of lawns and lakes. A more recent haunting occurred when a well-known country and western singer purchased a large antebellum mansion in Tennessee. After moving in, she and her family experience paranormal events. After studying the history of the town and mansion, she learned it was located on the site of a Civil War battle.

Unexplained Events
Another unexplained event occurred when Charlie Troxell was murdered in Portage Indiana. His father, Romer, drove from his home in Pennsylvania to view his son’s body in the morgue. Romer Troxell believed he heard his son’s voice directing him to the killer. Local police later confirmed Troxell helped capture his son’s murderer. Unexplained visions shortly before or after a loved one’s death have been reported numerous times.

Halloween, Depictions and Demons
The celebration of Halloween is an annual event that arouses interest in scary demons, witches and specters. Halloween is actually an ancient Celtic harvest festival. It celebrated the bounty of harvest and souls who died.

Cemeteries
Among ghostly locations, an historical, ancestral or military cemetery elicits a large number of eerie sightings. Some believe the dead haunt a cemetery to prevent desecration of graves. Native American Indian folklore is strongly attached to cemetery sites. Folklore and legends tend to add emphasis to ethereal beliefs.

Have You Ever Felt a Ghostly Presence?
Ghostly presences often occur during times of heavy emotional stress. Stress can originate from loss of a loved one or when the mind is crowded with confusion. The greater the sense of stress, the more the individual feels isolated from reality. A ghostly presence doesn’t have to appear in shape or form. It can be a feeling of extreme cold or “not being alone.” The phantom of an unresolved issue with a deceased individual is another example of ghostly presence that occurs day or night. It may be a memory jogged by some vague reminder lurking in the back of the mind.

Do Certain Places Scare You?
A dark attic, a lonely road or a vacant old home inspires the deepest sense of solitude. Humans are naturally averse to feelings of loneliness and isolation. Ethereal vibrations occur when humans place themselves in locations where there is emptiness surrounding them. Some believe that attics or vacant old homes evoke spectors of unrested souls who were unable to resolve serious issues before their demise. Dark or empty places conjure thoughts of the past from the sheer curiosity of previous people and events that occurred in these places.

Have You Ever Used a Medium?
A medium is the intermediary between the spiritual world and conscious world. The medium may be a person, place or thing. Fortune tellers, old wells, tea leaves, Tarot cards, crystal balls, prisms, runic stones and I Ching are depictions used.

Consciously, most people know it’s impossible to know the future. In reality, these are implements that heighten meditation skills. Many unconscious questions lie in human minds that affect meditation. These implements are centuries old and became practiced arts among highly sensitive individuals.

Summary
We see ghostly spirits because humans are naturally sensitive, intuitive beings. As the most intelligent life form, we seek answers to the unknowable.