We all know that in the land of the living, humans are made up of mostly water, but what happens when someone comes back from beyond the grave? How do they manifest into a ghost and what are spirits physically made of?
The defining property of a ghost is its lack of flesh, it's not made up of organic matter, blood and organs like a living human. But, if people are able to sense the presence of a ghost, detect them with ghost hunting gadgets, or even see an apparition, then there must be something measurable and tangible that creates them.
To answer this question we first need to break ghosts down into a couple of types of hauntings. There's a belief within the paranormal world that some ghosts are intelligent and capable of interacting with their surroundings, and then there's residual hauntings which are said to be merely events from the past being replayed.
Residual hauntings are thought to be an imprint of energy that has been left behind by someone who suffered a tragic, traumatic, premature death, usually a murder, suicide or execution. The energy used by the body and the brain in resisting death can be so immense that those events can be replayed either on the anniversary of the event, when atmospheric conditions are similar, or when someone is susceptible or in tune with that energy. The energy of strong positive or negative emotions may also cling to its surroundings.
The phenomenon is known as "stone tape theory" due to the belief that energy is captured and stored like a video recording in the surrounding bricks, woodwork, stone and possibly even the soil. When the conditions are right, these materials release this energy and you sense or see the event occur in exactly the same position as it did years ago.
As residual hauntings represent nothing more than a reflection of the past, you can't communicate with them. The visions seen are not aware of their surroundings. They cannot interact with you and are not aware of your presence.
Whatever form of energy is responsible for residual hauntings, it's clear that they don't have a physical presence as they don't interact with their surroundings and apparitions are often seen to pass through walls, often in locations where a door has been bricked up. The ghosts re-live the actions they performed when they were alive.
But parapsychologist, Dr. Hillary Bosnitch says "if we were to define ghosts as non-physical spirits that can't interact with their surroundings or the physical world around them then it is impossible to see one or interact with one in any way."
He suggests that if ghosts can't interact with their surroundings, then that would include not just objects, buildings and people, but would also mean they can't interact with the air, light, and other forms of electromagnetic energy around them. Light would not be able to hit a non-physical spirit and bounce off, which would mean they're not visible to the human eye. They would not be able to interact with the air around them, making speech and sounds impossible.
When it comes to intelligent hauntings it's a little different. These types of hauntings are the classic "ghost", they can reportedly move objects, push or touch people, slam doors and even throw objects across a room. So clearly when they manifest there is some kind of physical force behind them.
Many paranormal researchers believe that when someone dies, they continue to live on outside of their body as a form of electromagnetic energy, similar to the electrical impulses in the human brain. It's thought that it is this EM energy that is responsible for ghosts. This is why ghost hunters often use electromagnetic field meters to detect the presence of ghosts.
However, there are some who dispute these claims, especially those in the field of science. Professor Brian Cox thinks that the Large Hadron Collider has proved that there is no unknown or undiscovered psychic energy which is driving the body.
The huge particle accelerator at CERN (the European Center for Nuclear Research) accelerates subatomic particles to speeds approaching the speed of light, before slamming them together allowing scientists to discover new particles.
Professor Cox says, "I would say if there's some kind of substance that's driving our bodies, making my arms move and legs move, then it must interact with the particles out of which our bodies are made. And seeing as we've made high precision measurements of the ways that particles interact, then my assertion is there can be no such thing as an energy source that's driving our bodies."
If there were some kind of force or energy within our bodies that controlled our limbs and gave us our "life force" then we should be able to detect that energy interacting with the atoms within our bodies, but we don't which would suggest this force doesn't exist.
Paranormal investigators would argue that the paranormal falls outside of the realms of normal science and that it is by its very nature unmeasurable. But Dr. Bosnitch says that "the unmeasurable is essentially the non-existent."
There are a lot of inconsistencies when it comes to which materials spirits can manipulate, according to our expert, "ghost stories typically get this all wrong."
In almost all ghost reports the spirit switches states. Sometimes ghosts can interact with their surroundings, they're able to move objects, be seen by the human eye, or communicate using sound. Other times spirits can pass through solid objects, seemingly at will. Dr. Bosnitch gave the example, “think of Casper the Friendly Ghost, he can typically pass through walls, but walks on the floor.”
This leaves Dr. Bosnitch to question how this change of state occurs. He says, "assuming ghosts exists, how do they change state? Can they change state at will? Or is the change a result of environmental or atmospheric conditions?"
Perhaps the truth is, it doesn't really matter. While some ghost sightings can be written off as hoaxes, the majority of ghost sightings come from people who genuinely believe they have seen something supernatural. So whether ghosts are electromagnetic energy, a reflection of the past, or a trick of the mind, you can't take the experience away from someone who has witnessed a ghost.