Right away, you should know that it is the official position of Cracked.com and its parent company that we don't believe in bullshit. It's fun to think about bizarre unsolved myseries and wonder what's actually going on with the whole UFO thing, but we'll always defer to Occam's razor. A blur on a photograph is way more likely to be a weather balloon than a spaceship and a ghostly old woman wandering around an old church is far more likely to be a hallucination or, you know, an actual confused old woman.
There's a fine line between kooky and spectral.
It says nothing about our belief in an afterlife or lack thereof. There is simply no evidence that dead people wander aimlessly around old houses, and no known scientific principle that would make it possible. But a lot of people have seen ghosts. A lot. There are certain spots and buildings where separate, unrelated witnesses have reported ghosts independently, without having talked to each other or being aware of the area being "haunted."
It appears that science has stumbled across the reason for it. It has nothing to do with the supernatural, but the answer is almost as weird.
In order to understand the science we need to head back to the late 1950's. While working in his robotics laboratory Vladimir Gavreau noticed that one of his assistants was bleeding from the ears, despite the absence of rebelling robots choking him.
Puzzled, Gavreau started researching the phenomenon by holding vibrating pipes next to clueless assistants. We'll never know what excuse he used when they turned around and asked him why their ears were bleeding, but one way or another Gavreau soon realized that a vibrating pipe of the right length and girth can cause a number of unpleasant effects ranging from mild irritation to serious pain.
Above: the cause of all human suffering.
What he had discovered, aside from an awesome new way to torture interns, was infrasound. It's noise at a low enough frequency that you don't consciously hear it, but your ears still sense it. The process of receiving sensory input without your conscious mind understanding where it's coming from wreaks havoc with your emotions. Specifically, researchers found that sounds between 7 and 19 Hz it could induce fear, dread or panic.
Knowing this is an article about ghosts, you can already see where this is going.
They did an experiment where acoustic scientists sneaked in low frequency sounds at a live concert. Since scientists love nothing more than inducing feelings of fear and terror in unsuspecting citizens, most of the concert goers had no idea what was going on. As a result one minute they were enjoying some sweet tunes while the next a feeling of dread invaded their hearts, crushing all hope and happiness. At the end of the experiment approximately 22 percent of the people involved in the experiment reported feelings of unexplainable dread, chills and depression when infrasound was blasted into the crowd.
Why would it have this effect? It may be evolution. It doesn't take a mad scientist mind control device to create infrasound -- mother nature is creating this type of low frequency vibration all the time. Volcanos, earthquakes, strong ocean waves and even winds hitting the hillside in just the right spot can create infrasound. Even animals can create it, and tigers are particularly well known as a source. The frequency of a tiger's roar is around 18Hz -- right in that range we mentioned earlier.
All of the things that create the sound are huge, powerful and dangerous. Evolution might have taught us that this sound means Bad News.
Nature's way of saying "Shit your pants!"
So now we have a phenomenon that occurs in nature, is invisible, is imperceptible on a conscious level, but can spontaneously make you feel irrational fear, even if you're sitting in an empty room. Notice how we've just described one of the first and primary signs of a "haunting" -- unexplained feelings of fear or dread.
OK, but what about actual sightings of ghosts?
Well, for that we need to go to a researcher named Vic Tandy.