Séances were once performed in hushed, darkened rooms, but those locales have been supplanted by wowed audiences and stage lighting. A field once reliant on intimacy now favors auditoriums. The stereotypical foreboding Gypsy has given way to congenial men in tailored suits and women with impeachable manicures, ideal for television.

Most of this is done to make mediumship more appealing, but one change made out of necessity was the exorcising of ectoplasm. This was any substance said to have spewed from a medium during a séance, and it was usually touted as having been draped over the sprit’s body before being imparted to the medium. It was supposed to be the deceased letting us know it was there.

Ectoplasm was offered as an explanation for the levitation, table-turning, and floor-tapping that was observed during séances. But this was Tooth Fairy science, where the reasons for a phenomenon are examined before the phenomenon has been shown to exist. It was described as vulnerable to light, so séances were conducted in the dark, providing convenient cover for those sneaking the materials in or removing them from their hidden location, such as the medium’s clothing, a body orifice, or under a trapdoor.

Manifestations were common during the séance heyday from the late 19^th Century until the Great Depression. But after investigators exposed the ruse, ectoplasm fell out of favor with séance practitioners, and it had practically gone extinct by the middle of the 20^th Century. I am aware of no medium today that claims to be producing this netherworld substance.

Normally, an ad hoc rationalization is fabricated when psychic fraud is exposed. Uri Geller instantly lost his power when Johnny Carson offered Geller spoons and other items to demonstrate his ability during a Tonight Show appearance. Since Geller had been unable to manipulate the objects beforehand, he was unable to ‘bend’ them and was left meekly attributing his failure to “not feeling strong tonight.”

Another time, James Randi was conversing with three Russian alternative medicine practitioners who claimed to be in possession of some type of psychically-charged water. They claimed they could identify this magic water through a dowsing tool. Randi challenged them to go into separate rooms while he placed the magic water in a container, then filled two identical containers with tap water. The three would then enter individually and try to identify the magic water. At this point, the experiment abruptly ended, as one of the Russians said the magic properties would seep out and infiltrate the regular water, making them all indistinguishable. In these cases, Geller and the Russians had to come up with a hasty rationalization, lest their entire ruse be upended.

Similarly, I checked out a Flat Earth page and one of its claims was that a north-south circumnavigation has never been accomplished. This was in error, as Ranulph Fiennes and Charles Burton did it from Dec. 17, 1980 to April 11, 1982. I posted this, but the Flat Earther who maintains the page will not have an epiphany and become a globalist, so to speak. Despite the Fiennes-Burton journey being verified by the likes of the Guinness Book, the Flat Earther will dismiss the circumnavigation as fraudulent. And I may be outed as one of the tens of thousands of world government agents the page insists monitors the Internet 24/7 to spread the spherical Earth myth.

East-west navigation, of course, also proves a round Earth, but the Flat Earthers  have somehow convinced themselves this is untrue. From flateaerthsociety.org: “Circumnavigation is achieved because on a compass East and West are always at right angles to North. Thus traveling Eastwards continuously takes you in a circle around the North Pole.”

Actually, traveling east takes a mariner east, not north. But Flat Earthers have their rationale and they’re sticking with it. However, a north-south navigation would punch holes in their own theory, so it has to be dismissed out of hand.

Ectoplasm, then, is sort of the east-west circumnavigation of séances. Mediums can be OK with it going away since the central point of communicating with the dead remains. In fact, it makes it less messy.

Around the time that skeptics and researchers were exposing the ectoplasm ruse, other physical manifestations of séances were also coming undone. Hereward Carrington, a James Randi forerunner, revealed how slate writing, table turning, sealed-letter reading, and spirit photography were accomplished. Exposés like this largely eliminated physical props in in mediumship, but again, this was not a fatal blow to the field because the props were superfluous to yakking with the dead.

The research showed ectoplasm to come from a variety of sources, none of them supernatural. This included cheesecloth, chewed paper, cotton, cloth, gauze, egg whites, soap, muslin, starch, handkerchiefs, animal livers, and newspaper and magazine photos.

Despite a general idea of what ectoplasm was supposed to be, its appearance, consistency, color, elasticity, strength, and constitution varied by whichever medium was producing it. It could be dry or wet, viscous or gelatinous, opaque or transparent. None of this would not have been the case had ectoplasm been genuine. That would be like blood changing in type, texture, appearance, and color depending on which nurse was drawing it.

In 1924, Mina Crandon, one of the country’s most celebrated mediums, was tested by Scientific American and Harry Houdini, and was unable to replicate her ectoplasm powers under controlled conditions.

Another well-known psychic of the era, the mononymous Carrière, flunked a similar challenge. She had claimed, through ectoplasm, to have produced an image of a man. But this was revealed to have come from a magazine. She said, yes, she knew that. She had read the magazine and that’s how the image of the man came to be imprinted in her brain and later excreted as ectoplasm.

With all due respect to Geller, Russian quacks, and Flat Earthers, that gets my vote for the all-time greatest ad hoc reasoning.

There are three primary explanations for supposed ghost photos. They could be the result of a defect, a hoax, or a ghost.

In the case of defects, the image normally looks like whatever ghosts are said to look like in a given time and place. Photographs of allegedly inexplicable bright orbs are sometimes said to be a person’s spirit, and such shots are frequent consequences of today’s technology. By contrast, the orb would merely have been a distraction in 19^th Century photos since ghosts were then thought to be transparent, floating apparitions who kept their clothes on when they passed to the other side.

Hoaxes are easy to pull off today, but it is also easy for PhotoShop experts and other professionals to detect them. Before the ubiquity of cell phones and camcorders, still film images were allegedly the primary means for spirits and souls to manifest themselves. In truth, the science behind photography could always explain the anomaly. Even if a case ever came along that baffled the foremost photographers, it would not be proof of a ghost. It could be a world class hoax, an innovative photography technique, or something else. Passing it off as a ghost because we aren’t sure what it is would simply be negative evidence. If ghosts could be captured in still or moving pictures, we would see many instances of this, especially in morgues, hospitals, and scenes of fatalities. Photos and videos taken during and after 9/11, Oklahoma City, Waco, D-Day, and natural disasters are all ghost-free.

Which is why the final explanation is by far the least likely. Also, how a ghost would manifest itself on film or video has likely never been tested via the Scientific Method, and these ideas have certainly never been confirmed. Believers have likewise proffered no explanation for the process by which a person becomes a ghost. Even undertaking these challenges would be to embrace Tooth Fairy Science, which is when the specifics of a phenomenon are investigated before the phenomenon is confirmed to exist.

This shortcoming has been no issue for paranormal investigators. Ghost hunting has been around for at least two centuries, but séances with mediums have largely been replaced by a glut of programs on third-tier TV channels, YouTube, and other mediums. Besides small video cameras and phones, the hunters are invariably wielding an assortment of other electronic gizmos and doohickeys.

Most of these pieces do indeed function as detectors, as they are intended to detect light, heat, movement, or electromagnetism. The substantial problem arises when one interprets those readings as ghosts as opposed to readings of what they are meant to measure. There is no science to suggest that ghosts emit anything in measurable amounts.

So when ghost hunters uses an infrared thermometer or motion detector to pinpoint a cold spot in a room, they might find such a location. While there is no reason to think ghosts are responsible for temperature changes, those chasing them might be causing it since more persons in the room will raise the temperature. Changes are also caused by heating, air conditioning, insulation, studs, wiring, pipes, radiant heat, sunlight, and wind.

Another item, particle detectors, make infrequent appearances in ghost hunts. But as Brian Dunning at Skeptoid put it, “For a ghost to emit ionizing radiation, it would have to be an awfully sick ghost or be composed largely of unstable radioactive metals.”

EMF meters are said by hunters to detect ghosts, though this claim is never augmented with any suggestion of what the deceased wanderer’s power source is. Also, Dunning wrote that, “Given the massive amount of EMF pollution on a TV ghost hunting set, the idea of being able to detect the EMF field of a ghost who’s not carrying any batteries is ridiculous.”

Skeptic Kenny Biddle found he could set off an EMF detector with just a computer mouse. But what should be seen as a major flaw is seen as a plus by ghost hunters. Their devices are erratic, highly susceptible to false positives, and have blinks and beeps that make it seem to believers like something ghostly is happening. Throw in some strange sounds that seem even more frightening in a darkened castle or mansion and you’ve hit poltergeist pay dirt.

Though they haven’t been used much since being brushed aside by electronics, dowsing rods are still utilized by a few ghost chasers. Whether the rod moves, and in what amount and in what direction, is determined by the hunter, who also interprets and announces what this movement means. His claimed ability cannot be tested, measured, or duplicated by another person, nor has any dowser proposed a plausible hypothesis for how this would work.

Usually touted as the spookiest fruit from hunts is ghostspeak on audio. These mystic missives might seem unsettling, but that’s only because they are so garbled and distorted. They are drenched in static, vary in pitch, and produce an unpleasant sound that can come across as someone who is pained, scared, or angry. In the many thousands of hours of these recordings, we have yet to have a ghost articulately announce in plain language, “Here I am. I am the ghost of King John’s tailor.” Ghost hunters claim that their prey speak on a plain that can only be captured by recording devices, providing another example of how they fundamentally misunderstand what these items are for and how they work. The proof of ghostspeak is so tenuous it has  included rationalizations that the same ghost is speaking in different languages within the same sentence, or that it will speak backwards only some of the time.

The Atlantic related the tale of what was likely the first ghost story of the photography age. In 1861, William Mumler noticed the shadowy figure of a young girl on a plate he was developing. He knew the cause was that he had inadvertently reused a plate that had been insufficiently exorcised of its previous image. He showed it to his spiritualist friend as a prank, which the friend gullibly swallowed. When Mumler tried to explain what had really happened, the friend refused to believe it and even had the image printed in spiritualist publications.

This started a trend that continues today, as almost any new recording or electronic device can be used to further the ghost hunter’s agenda. Beginning with Mumler’s double-exposed photo, telegraphs, telephones, cassette recorders, radios, televisions, camcorders, the Internet, iPhones, and Fitbits have all been seized on by believers as a means to access the paranormal realm. The only medium they haven’t penetrated is a peer-reviewed journal.

Most ghostly encounters center on location. They are more likely to occur in a 19^th Century three-story New England mansion than in subdivision ranch home, and much more likely than at a Sav a Lot. They occur in homes built on former Indian burial grounds, but probably not on the site of a former fabric store. Also relevant is the time of day, as most ghostly encounters occur at night.

However, there may be larger factor than location, time, or even expectation. This was addressed in an article in Cracked, which has undergone one of the more amazing transformations in U.S. pop culture history. Once a Mad Magazine clone, it is now an online source with insightful articles on a broad range of topics featuring humor, intelligence, and social commentary.

And one of its articles told the tale of how a lab assistant’s ear bleed led to a potential discovery about what really happens during ghostly experiences. Scientist Vladimir Gavreau noticed his assistant was bleeding from the ear and, in the spirit of discovery and strangeness, put various vibrating pipes near the assistant and discerned that pipes of a certain length and weight led to mental and physical discomfort for the assistant. Garvrea had discovered infrasound, which is noise whose frequency is low enough that humans can sense it but not hear it. The hypothesis is that it drives a person bonkers to receive sensory input without knowing where it’s coming from.

This was put to scientific, albeit unethical, test when low frequency sounds were unleashed on an unwitting concert audience, with 22 percent reporting feelings of dread, chills, and depression. Researchers have found that sounds between seven and 19 Hertz can elicit these symptoms, along with nausea, disorientation, and loss of equilibrium.

A more proper test was conducted by engineer Vic Tandy after he and fellow researchers experienced all these unpleasantness in their laboratory. For added spookiness, they were also seeing gray shapes out of the corner of their eyes. Tandy deduced that these experiences were confined to a specific section of the laboratory. Also in this location, metal sheets would vibrate uncontrollably when placed in a vice.

He traced the culprit to an air conditioner ventilator emitting low frequency vibrations that bounced off the lab’s walls at 18.9 Hertz. It was even powerful enough to cause the blurry peripheral vision because the vibrations were subtly affecting the eyeballs. Once the ventilator was removed, the fear and apparitions disappeared.

Tandy further tested this idea in an allegedly haunted abbey. Local lore had it that visitors to the abbey cellar would become nauseous and see gray ghostly images in their periphery. Tandy investigated and learned the cellar’s shape was creating a chamber that caused frequencies to resonate at 18.9 Hertz. Unlike Ghost Hunters, engineers actually find what they are looking for, but no one would watch a show that solves the mystery after one episode.

I pride myself on considering new ideas and challenging my preconceptions. When I first heard that race was social construct, it contradicted what I thought I knew and what I considered to be reasonable, perhaps even obvious. But setting that bias aside and considering the science and evidence, my position changed. And it will change back if a better case is made for race realism. I have, in fact, read three essays that purported to make the case for race being a biologic reality. But they were skimpy on the science and failed to even identify the races, so my position for now is that race is a social construct. Similarly, while praising the Scientific Method and peer review, I have included in my blog an overview of the shortcomings and potential for manipulation contained within them. My primary interest is finding and promoting the truth.

So while the infrasound explanation is attractive to a skeptic, I must point out that not all studies have reached this conclusion. One example of this was a double blind study conducted by Dr. Richard Wiseman and associates. For the study, actor Todd Robbins read a story about a professor who had been murdered in the hotel room the volunteers had assembled in. All the while, low frequency sounds were pumped in (or not, depending on which group it was). The results showed no statistically significant difference in responses between the group that was exposed to infrasound and the group that was not. Nor was there any difference in the reactions of self-described skeptics and self-described believers.

For now, there have not been enough studies conducted on this issue to reach a sound conclusion. The Wiseman experiment may prove to be an outlier, or it may be part of metadata that refutes the infrasound-instead-of-poltergeist hypothesis. In science, nothing is ever proven, we can only add to the body of evidence that suggests one outcome is the most likely one. The feelings of dread may come from infrasound, they may come from ghosts, but whatever the source, we’ll keep searching for it, and that is good science.

Electronic voice phenomena are recorded sounds that are interpreted by some as spirit voices. Without exception, this ghostspeak is limited to incoherent hisses in one to three word bursts.

When one can make a phrase out of it, it is likely the result of apophenia, the mind’s tendency to perceive patterns in random stimulus. It is what causes people to see a Face on Mars or Jesus in their Post Toasties. Other factors in hearing spirit voices on recordings are expectation and desire, but the biggest influence is equipment shortfalls.

Sound engineer David Federlein has noted that despite using much higher quality equipment than most EVP researchers, he has “never heard from the dead and I have been listening to tape and hard disc recordings for years. EVP are usually recorded by raising the noise floor – the electrical noise created by all electrical devices – in order to create white noise. When this noise is filtered, it can be made to produce noises which sound like speech. When you factor in other aspects of physics, such as cross modulation of radio stations or faulty ground loops in equipment, you have a lot of people thinking they are listening to ghosts when in fact it is nothing more than a controlled misuse of electronics.”

Indeed, sample rate conversion, vibration isolation, and noise alteration can all cause recordings to assume qualities separate from what they originally picked up. Even meteors can be a factor. While hurtling through Earth’s atmosphere, they leave a wake of ionized particles and electrons that can reflect transmission radio waves. The resultant sound lasts no more than a second, but it can transform a message sent via CB, cell phone, baby monitor, or ham radio into a wail of torment from a 16^th Century knight.

As an anti-vax message on the Internet shows, scientific advances can be coopted by anti-science forces. So the advent of film and audio enabled mediums and ghost hunters to bolster their charade. One of the first instances of this was Attila von Szalay in the 1920s. He conducted recording sessions using a microphone in an insulated cabinet connected to an external recording device and speaker. He reported finding sounds on the tape that could not be heard on the speaker when he recorded. He interpreted these extraneous sounds to be voices from the netherworld.

Opening our skeptic toolkit, we find three items. First, von Szalay is employing Tooth Fairy Science, where research is conducted on a phenomenon before establishing that the phenomenon exists. This leads seamlessly to the next problem, the logical fallacy of affirming the consequent. Von Szalay insinuates that if we hear voices, it means ghosts are speaking, and we indeed hear those voices, so voilà. Also crucial is that he never established that any of the equipment could be used for the purpose he was claiming. As an amusing postscript, the ghostly missives included “This is G” and “Hot dog, Art.”

In the early 1980s, William O’Neil constructed an electronic audio device called the Spiricom, which he said could enable him to dialogue with the discarnate. But he committed the same errors as von Szaly and, furthermore, no one was able to replicate his results using the device, meaning either that it didn’t work or only O’Neil had The Gift.

Along the way, Sarah Estep founded the American Association of Electronic Voice Phenomena and put this Tooth Fairy Science on an even grander stage by announcing that the voices came from other planets or dimensions.

It is telling that the only persons who pick up these voices are those that are specifically looking for them, even though EVP researchers use the same type of equipment as sound and video broadcasters, engineers, and producers. The spirits never announce their presence on CNN or NPR. Then again, maybe the discarnate favor the darkened rooms, hushed tones, and frightened hosts that shows like Ghost Hunters employ.

Except for being potential topics on a skeptic blog, there would seem to be no connection between ghosts and psychic animals.

But they may have a common explanation through infrasound. These are extreme bass sounds under 20 Hertz, which is too low to be heard by humans, unless at a decibel level much higher than infrasound usually reaches.

Humans make infrasound with large music pipes, detonations, rocket launches, and sonic booms. It is also produced during large releases of energy, such as in extreme weather, earthquakes, meteor explosions, and turbulent mountain air.

Though inaudible, the sound can cause strange and uneasy feelings. These feelings are sometimes akin to seasickness, except the sufferer can never get off the ship. They stay queasy as long as the infrasound continues to pump. It can also cause unease, fear, dread, and sadness, as well as well as unpleasant physiological effects such as nausea, disorientation, and loss of equilibrium. The French movie “Irréversible” included infrasound in its opening scenes to produce these sensations in audience members. It was also tried on a suspecting crowd. During a controlled experiment in a British concert hall, scientists were able to instill morbid feelings in volunteers via infrasound. These feelings included melancholy, chills, and anxiety.

Nazi engineers recognized the phenomenon and tried unsuccessfully to build an infrasound weapon. It would have been quite the tussle if both they and Stalin’s mad scientists had succeeded, and auditory bombers had squared off against ape-men.

Infrasound may explain alleged paranormal activity since it cannot be seen, heard, or felt, yet overtakes people with feelings of fear, dread, and sadness.

Infrasound can also be used to monitor for earthquakes and volcanoes, and some animals can hear and communicate at this frequency. This may explain why they sometimes flee before natural disasters, and the ability is sometimes credited as being animal intuition by the New Age camp. Less frequently, creationists will claim it is God telling the rabbits and moose to commence their scurrying.

Besides poltergeists and animal mysticism, some have tried to connect spiritual experiences at church to long pipe organs that can produce infrasound. I find this unlikely. For one, these uplifting experiences are reported in all churches, the vast majority of which don’t have this musical capability. Also, the feelings reported are the opposite of dread and fear.

The strongest piece of evidence for infrasound’s impact was provided by Vic Tandy, a part-time law lecturer at Coventry University in England. Tandy had a pair of unsettling experiences at the school. First, he felt the unease associated with infrasound while also seeing a gray blob come at him out of the corner of his eye. Another time, his fencing foil was moved by strong vibrations. It is unclear why a law lecturer was armed with a fencing foil, but I’m guessing it was in case the gray blob came back.

Frightened, but determined to find a scientific explanation, Tandy used instruments to measure sound waves and see what he could detect. As a control, he did this during the daytime with others in the room, and checked to see if the dread returned and the foil vibrated. In both cases, they did. Tandy eventually deduced that infrasound was coming from a ventilator in the air conditioner. When the air conditioner was turned off, the vibration and sinking feeling both stopped. This finding suggests that infrasound is a possible explanation for some instances of Sick Building Syndrome.

And it likely goes a long ways toward explaining many paranormal experiences. Ghosts don’t haunt newly-opened malls or condos, but prefer mountain castles, and there is a connection beyond ghost hunters expecting to find them there. Mountaintop castles are regularly bombarded with strong gusts of wind, which can make their way through tunnels and winding staircases and manifest as infrasound. This can be interpreted as paranormal, especially when combined with the post hoc reasoning of attributing any bumping sounds and beeping electronic gadgets to a ghostly presence.

The chilling image darts across the surveillance video, a vaguely human-looking figure gliding past the police station entrance in Espanola, N.M. The video made the national rounds, being aired on CNN and Good Morning America.