May 232012

In 2009 a survey was done that found that 4 out of 10 people in the UK believe in ghosts. But in scientific terms is it enough to say something is true just because a large number of people believe it?


After all, everyone used to believe the world was flat until there was enough proof that it wasn’t. A belief in ghosts is very much a personal thing, but if they really don’t exist, how can we  explain some of the spooky things that go on? The ghostly figures, the hairs on the back of your neck standing up, the unsettled feeling in your stomach? Can science shed any light on the subject?

Some years ago an engineer called Vic Tandy was working on his own in his lab (they always are, aren’t they?!) and he had a ghostly experience. It was a very old building and out of the corner of his eye he saw a flash of white that appeared to move across the room, and he started to feel very odd. The next evening he was alone again and fixing a fencing foil, which is a long and very thin blade. He had it held tightly in a clamp on the bench with the blade pointing upwards and suddenly the blade began to swing about.

Despite being pretty scared he decided to try and measure what could be making the blade move. Knowing that sound waves could cause movement in air and objects, he decided to get out a machine that could measure sound. He knew he couldn’t hear any sound but the machine showed a high level of sound below the level humans can hear. Very, very low-pitched sounds that we can’t hear are called ‘infrasound’. In an empty building when everything else is still, moving machines, such as fans or air conditioners can create these infrasound waves. Even something as simple as an open window with the wind blowing outside could cause the effect. But why would this ‘silent’ sound wave make you see and feel things that aren’t there?

Well, every part of your body – depending on size and shape – will tend to vibrate if the right sound is played. Your eyeballs like to wobble at about 19 times a second so if a sound wave matches that, it would create very small movements in your eyes. This movement means your eyes could fire off false messages to the brain that then thinks you are seeing movement that isn’t there. Possibly an explanation for the ghostly images people report seeing?

Not only this, but your stomach has a low vibration rate too, so infrasound can make you feel a bit sick or uneasy. Scientists have tried this out by adding infrasound to music and, although you can’t hear it, people have reported feeling very uneasy when the infrasound is playing. Quite a lot of ‘haunted’ houses have been show to have infrasound in them, and it seems that if the effect is strong enough it can even make physical objects move (like with Vic’s fencing blade). Perhaps this is even an explanation of poltergeist activity?

I think many people like to believe in ghosts because the alternative idea of a life ending when we die is too hard to accept. Science alone certainly can’t give us all the answers on this one yet…

 Taken from Why Do Golf Balls Have Dimples?: A Book of Weird and Wonderful Science Facts

 May 23, 2012  Add comments

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