Each year around the end of October we feature plenty of Halloween-related projects, usually involving plastic skeletons and LED lights, or other fun tech for decorations to amuse kids. It’s a highly commercialised festival of pretend horrors which our society is content to wallow in, but beyond the plastic ghosts and skeletons there’s both a history and a subculture of the supernatural and the paranormal which has its own technological quirks. We’re strictly in the realm of the science here at Hackaday so we’re not going to take you ghost hunting, but there’s still an interesting journey to be made through it all.

Today: Fun For Kids. Back Then: Serious Business

Halloween as we know it has its roots in All Hallows Eve, or the day before the remembrance festivals of All Saint’s Day and All Soul’s Day in European Christianity. Though it has adopted a Christian dressing, its many trappings are thought to have their origin in pagan traditions such as for those of us where this is being written, the Gaelic Samhain (pronounced something like “sow-ain”). The boundary between living and dead was thought to be particularly porous at this time of year, hence all the ghosts and other trappings of the season you’ll see today.

Growing up in a small English village as I did, is to be surrounded by the remnants of ancient belief. They survive from an earlier time hundreds of years ago when they were seen as very real indeed, as playground rhymes at the village school or hushed superstitions such as that it would be bad luck to walk around the churchyard in an anticlockwise manner.

As a small child they formed part of the thrills and mild terrors of discovering the world around me, but of course decades later when it was my job to mow the grass and trim the overhanging branches in the same churchyard it mattered little which direction I piloted the Billy Goat. I was definitely surrounded by the mortal remains of a millennium’s worth of my neighbours, but I never had any feeling that they were anything but at peace.

Some Unexplained Phenomena Are Just That

So as you might expect, nothing has persuaded me to believe in ghosts. I can and have walked through an ancient churchyard at night as I grew up next to it, and never had so much as a creepy feeling.  I do however believe in unexplained phenomena, but before you throw a book at your computer I mean it in the exact terms given: observable phenomena we know occur, but can’t immediately explain.

To illustrate, a good example of a believable unexplained phenomenon was those moving rocks in an American desert; they moved but nobody could explain how they did it. It’s now thought to be due to the formation of ice underneath them in certain meteorological circumstances, so that’s one that’s no longer unexplained.

As another slightly less cut-and-dried example there are enough credible reports of marsh lights to believe that they could exist, but the best explanation we have, of  spontaneous combustion of high concentrations of organic decomposition products, remains for now a theory. I hope one day a scientist researching fenland ecosystems captures one on their instruments by chance, and we can at last confirm or deny it.

The trouble is with unexplained phenomena, that there are folks who would prefer to explain them in their own way because that’s what they want to believe. “I want to believe” is the slogan from the X Files TV show for exactly that reason.

People who want a marsh light or the sounds made by an old house as it settles under thermal contraction at night to be made by a ghost, are going to look for ghosts, and will clutch at anything which helps them “prove” their theories. In this they have naturally enlisted the help of technology, and thus there are all manner of gizmos taken into cemeteries or decaying mansions in the service of the paranormal. And of course in this we have the chance for some fun searching the web for electronic devices.

All The Fun Of Scam Devices

In researching this it’s been fascinating to see a progression of paranormal detection equipment over the decades, following the technological trends of the day. From early 20th century kits that resembled those used by detectives, to remote film cameras like the underwater Kodak Instamatic from a 1970s Nessie hunt we featured earlier this year, to modern multispectral imaging devices, with so much equipment thrown at the problem you’d expect at least one of them to have found something!

I’ve found that these instruments can be broadly divided into two camps: “normal” devices pressed into ghost-hunting service such as thermal cameras or audio recorders, and “special” instruments produced for the purpose. The results from either source may be digitally processed to “reveal” information, much in the manner of the famous “dead salmon paper“, which used an MRI of a dead fish to make a sarcastic comment about some research methodologies.

I’ve even discovered that I may have inadvertently reviewed one a few years ago, a super-cheap electric field meter touted as helping prevent some medical conditions, which I found to be mostly useful for detecting cables in my walls. Surprisingly I found it to be well engineered and in principle doing what it was supposed to for such an instrument, but completely uncalibrated and fitted with an alarm that denounced the mildest of fields as lethal. At least it was a lot cheaper than an e-meter.

Tomorrow night, there will be those who put on vampire costumes to be shepherded around their neighbourhoods in search of candy, and somewhere in the quiet country churchyard of an Oxfordshire village, something will stir. Is it a spectre, taking advantage of their yearly opportunity for a sojourn in the land of the living? No, it’s a solitary fox, hoping to find some prey under the moonlight in the undergrowth dividing the churchyard from a neighbouring field.

Wherever you are, may your Halloween be a quiet and only moderately scary one.

Header: Godstone, Surrey: Gravestone with skull and bones by Dr Neil Clifton, CC BY-SA 2.0.