What's the Science Behind Ghost Hunting?

Some people think ghosts are fake, just a figment of imagination or an elaborate physics trick. Others — 34 percent of Americans — swear they feel some otherworldly presence. And among those that do, there’s the sliver of the population that become ghost hunters, who claim to use science to track down ghosts. (Many ghost hunters actually prefer to go by the title “paranormal investigator.”)

Semantics aside, how much science is in ghost hunting?

Admittedly, the endeavor does use equipment typically reserved for scientific and technological investigations. Today’s ghost hunters are equipped with devices like EMF meters, digital thermometers, video cameras fitted with infrared and night vision, audio recorders and, of course, computers and smartphones that are capable of analyzing that treasure trove of paranormal data.

Here’s a peek into the typical ghost hunter’s tool belt:

• Electromagnetic-field meter

• Geiger counter

• Digital thermometer

• Thermal-vision camera

• Infrared camera

• Digital sound recorder and audio software

• Camera or video camera

• Night-vision goggles

Every piece of equipment is supposed to help the hunter observe some sort of indicator that a ghost is in the vicinity. And in each case, there are holes in that logic.

We’ll start at the top, with electromagnetic-field meters, or EMF meters, which are some of the most important instruments cited by ghost hunters. An electromagnetic field is produced by an electrically charged object. EMFs are everywhere in the universe and are part of the four fundamental forces of nature (the others being gravity, weak interactions, and store interactions). An EMF meter basically detects changes in nearby EMFs.

And what do EMFs have to do with ghosts? We’re not exactly sure, actually: If ghosts exist, we don’t know if they would emit electromagnetic fields. And why would they? Are ghosts actually electrical beings floating around spewing bits of charged-up ions as they float around? Nobody really knows. A number of different things could set off an EMF meter, like a microwave, a laptop, or a flat screen television.

The same thing applies to Geiger counters, which measure changes in ambient radiation in the surrounding area. Are ghosts radioactive? Maybe, maybe not. Unless you’ve exhausted all other possible origins for a spike in radiation (as well as eliminated the possibility you’ve invested money into a poorly made Geiger counter), higher radiation readings don’t equate a supernatural presence.

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Temperature is another factor, although it plays into a more tangible experience than the other two tools. There’s a strong belief that temperatures in a room go down when a ghost is around. A thermometer wont just read this — it’s something the ghost hunter (and others in the room) can feel for themselves.

The problem is most ghost hunters are using temperature-measuring tools that are meant to measure surface temperatures, not ambient temperatures. Digital thermometers, thermal-vision cameras, and infrared cameras aren’t optimized to pick up changes in ambient temperature — just solid objects (and we all know ghosts aren’t solid!). Furthermore, thermometers that do measure ambient temperatures can’t really do so as rapidly as you might think — it takes a few minutes to correctly adjust and read out the new measurement. If a ghost rapidly appeared and disappeared, none of this equipment would correctly pick up these changes.

There are two counterarguments a ghost hunter might put forth. The first is that even if the equipment can’t pick up immediate temperature decreases, the human body could. A ghost hunter might say they felt the room get colder. But humans are fickle — just walk into any goddamn office in the summer and see how many people claim it’s too hot or too cold in just one corner of the office, and how many times they might change their mind in five minutes.

The other counterargument is that temperature changes in objects themselves don’t occur that rapidly. But science says no. Solid objects can carry a lot of energy (aka heat) — and they can release that energy for a number of strange reasons.

Ok, fine, none of this seems to work. But what about audio recorders, cameras, and night vision goggles. The things heard and seen through this equipment are too variable on a case-by-case basis to really go into, but needless to say there are a ton of different reasons why a photograph might pick up an aberrant white streak of light in the corner, or why a recorder might pick up a hissing noise in the background. There’s a lot weird shit in old, supposedly haunted houses that can mess with our sense of what’s normal and what’s not. The optics in cameras and the auditory components in recorders are strange and bizarre and don’t always work as we’d like. When a camera picks up red eye in people, that doesn’t mean they’re demons.

When it comes down to it, a lot of ghost hunting is simply intuition — you go in convinced ghosts exist, and you’re looking for strange activity that will emphasize and confirm that belief. None of the data is definitive proof of the presence of ghost. More often than not, there’s a plausible explanation for why these tools detect what they detect. And in those other instances where there is no good explanation for a phenomena, it’s a bit silly to jump to ghosts.

And in the instances there is no good explanation, that doesn’t mean the answer is ghosts. In short, science says ghosts are not real.

However, if you are interested in digital hauntings, here’s a ghost currently harassing me on Twitter.