Science itself can be spooky enough, yet millions of people believe in ghosts: a 2005 Gallup poll found that over a third of Americans reckon houses can be haunted, while some 32 per cent believed specifically in ghosts. More recently, a 2013 HuffPost/YouGov poll indicated that 45 per cent thought ghosts exist.
According to some, a ghost is the spirit of a dead person that either has not moved on to the ‘afterlife’ or has returned from it. The definition of ‘spirit’ can also vary: some describe it as a person’s soul, while others believe it is an energetic imprint that a person leaves on the world.
Although many people genuinely believe they have experienced a ghostly encounter, scientists argue that there is usually a more prosaic explanation. So what’s really going on?
It’s all in the mind
Certain sleep states and altered states of consciousness can lead people to believe that they have experienced something paranormal. For example, hypnogogic hallucinations may explain reports where people see spirits while in bed. Most people experience a hypnogogic trance once or twice in their lives, although it’s far more common in people with epilepsy or certain sleep disorders.
Indeed, experiments amongst epileptics in which scientists stimulated the left temporoparietal junction – the part of the brain that defines the idea of self – prevented subjects from differentiating between themselves and ‘others’, and created a copycat shadow person in the subjects. Researchers speculate that this may be the reason why some people encounter ‘shadow beings’ and ‘aliens’ or have out-of-body experiences. Equally, electrical stimulation of the angular gyrus can cause the sensation of someone behind you mimicking your movements.
Other research has found that when we gaze around in a poorly lit environment, our brains may see things that are not really there. “Everything we see is an hallucination generated by the virtual reality machine inside our head,” argues Prof Mike Morgan of The City University, London. “Normally these hallucinations are vetoed by the information coming through our senses, so we can call perception ‘controlled hallucination’.” However, if the input is ambiguous our brains can ‘fill in the blanks’ and fool us into ‘seeing’ things that are not really there.
Researchers have also found that people report more strange experiences in areas where others have ‘experienced’ unusual phenomena in the past.
power of suggestion
Ouija boards have been popular with those trying to interact with spirits for a couple of centuries. Similarly, table tilting is a phenomenon that was often encountered during séances. People gathered around a table for a séance found to their consternation that sometimes it would start to ‘move by itself’. Although confidence tricksters were involved on occasions, scientists have also detected another phenomenon at work.
Experiments by the renowned physicist Michael Faraday indicated that the tables often moved because of the so-called ‘ideomotor effect’: under certain circumstances the power of suggestion causes our muscles to work unconsciously; thus, when people expected a table to move, they unknowingly moved it.
Psychics often refer to ‘vibrations’. It turns out that vibrations may indeed be involved in some paranormal activity – but not in the way spiritualists suggest.
Humans can hear sounds up to 20,000 Hertz, but we’re unable to detect anything lower than 20 Hz. We can’t hear sounds beyond these frequencies but we can detect them in other ways. For instance, we can feel them resonating in our stomachs, and this can influence our mood significantly. Infrasound can also cause resonance effects in our eyeballs, which may spark hallucinations. Infrasound can be produced by wind and weather patterns or everyday phenomena like traffic movement or household appliances such as electric fans.
Automatism represents a state of ‘altered consciousness’ where people say things and think things they’re not aware of. When a psychic clears her mind, a spirit guide is supposed to enter her body and communicate with her. However, scientists argue that, when the random ideas and images start popping into her head, they stem from her mind rather than another entity.
Ghost hunters often consider a cold spot in a house to be an indicator of paranormal activity. Scientists argue there’s usually a more down-to-earth explanation, such as cold drafts entering through a chimney or window, or convection currents. Turning up the heating is one way of exorcising this type of ghost!
As with UFOs, ghosts recorded on camera tend to have a rational explanation. For instance, ‘orbs’ may be caused by a speck of dust that show up as a blurry circle in a photo, and can be enhanced through interaction with flash and other lighting. Photographers have long been aware of lens and diffraction effects. Other photos, of course, turn out to be out-and-out fakes.
As an odourless, colourless gas, carbon monoxide is hard to detect. When taken up by our red blood cells (erythrocytes) it prevents them from absorbing oxygen. The resulting victims of oxygen deprivation often experience symptoms ranging from weakness and nausea to confusion and, eventually, death. They may also experience hallucinations: there are numerous incidents of people reporting strange happenings, which when investigated, have turned out to be carbon monoxide-induced hallucinations, caused by a faulty furnace or water heater.
A psychological phenomenon known as mass hysteria has been responsible for some reported instances of hauntings. Collective delusions sometimes occur amongst people in stressed school or workplace environments. The pent-up stress may manifest itself in physical symptoms like headaches, nausea, or violent spasms. If strong religious or cultural beliefs are involved, along with a relatively isolated environment, rumours can spread rapidly along with the physical symptoms.
A favourite bit of kit for a ghost hunter is something called an ion counter: it measures the level of charged particles in the atmosphere. A high concentration of ions is often seen as an indicator of something unusual by enthusiasts of the paranormal. However, ion counters pick up all kinds of natural phenomena like weather, effects caused by the solar wind, and naturally occurring radiation, for instance from radon gas. Interestingly, concentrations of both positive and negative ions can affect our moods, but in different ways: negative ions can make us feel calm and relaxed while positive ions may give us a headache and make us feel poorly.
Equally, ‘strange’ magnetic fields – another ghost-hunter staple – may be attributed to localised phenomena that stem from electronic equipment or geological formations. Some research indicates that such fields can interact with the brain to cause hallucinations, dizziness and other neurological symptoms. One theory suggests this explains why people report more ghostly activity at night: the solar wind causes Earth’s magnetic field to extend on the side that’s in darkness; it’s this expanded field that interacts more strongly with our brains.
We’ve already discussed ‘spooky action at a distance’ in another blog, but quantum effects have been postulated by some scientists as forming the basis of people’s concept of a soul. Dr Stuart Hameroff and physicist Roger Penrose hypothesised in 1996 that human consciousness stems from the presence of microtubules inside our brain cells that are responsible for quantum processing. The pair believe that, when people have a near-death experience, all the quantum information leaves the brain, yet continues to exist and can be subsequently recalled, which is why some people report out-of-body experiences and ‘light at the end of a tunnel’. Many scientists are sceptical of this idea but Dr Henry Stapp, a colleague of Heisenberg’s, suggested that a person’s personality might be able to transcend death to exist as a ‘mental entity’.
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