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Real World Physics Problems Newsletter - Ghosts, Issue #46
July 29, 2018


Those interested in the paranormal will have certain beliefs as to whether or not ghosts exist. I can admit to the fascination in ghosts, especially when I was growing up. The concept of ghosts is something that taps into your deepest primitive fears and curiosity. But what does science have to say about ghosts? If there is one particular science that can be dedicated to the study of ghosts it surely must be physics. So what does physics have to say about ghosts?

There are many, many anecdotal stories about ghosts from people who claim to have seen, heard, or otherwise experienced something caused by ghosts. Some sound really convincing, and others go so far as to bring scientific measuring and recording instruments to capture evidence of ghosts. There are audio and video recording devices, and also infrared cameras which detect temperature variations. And it seems quite reasonable that these devices have indeed captured unexplained phenomenon. I've seen television shows talking about these things, and some is likely fake, but I'm a big believer in there being evidence of a lot of unexplained goings-on out there in the world. That doesn't mean I believe in ghosts though - I don't - but you can certainly experience something that cannot be explained easily using conventional knowledge. This applies to alien sightings as well as ghost sightings.

Perhaps the biggest tell-tale that ghosts don't exist is that they are always in the so-called "edge" of perception, where you might see something out of the corner of your eye, or you see something that is far away, or kind of blurry, or both. Or you observe something in a one-time not-so-clear fashion, with no repeat. The signal to noise ratio is always poor in these situations. Ideally, a ghost would present itself in full view at least some of the time. Why always stay out of sight, or barely out of sight? If ghosts do this deliberately then surely they would make a mistake some of the time and appear in broad view once in a while, when they didn't intend it.

Still, the concept really does intrigue me. Not too far from where I live there is this historical site that claims to have frequent ghost sightings. I just may have to check it out for myself. Perhaps there are clever people at work who have something orchestrated in which they produce ghost experiences at regular, and yet random times, to attract more visitors. You can't rule that out. I can think of a few ways to create conditions which can make you think there might be a ghost around. For example, I can run a thin string through a small hole in a wall and attach it to a door in the next room, and then yank on the string when I know there are other people in the room, and then quickly pull the string through the hole before someone sees it. The sudden jerking motion of the door would certainly inspire thoughts of ghostly activity. I could also release a cold pocket of air into a room (somehow) so that the person in contact with it thinks a ghost moved past him. The pocket of air would then quickly dissipate and warm up, and no one would know what really happened.

The point is that there are ways to create the illusion of ghosts using physics. Crop circles are an example of an elaborate human hoax which is believed by some to be caused by aliens. As it turns out, humans often love to trick other humans. Who knew?

Notwithstanding, I have also often wondered if there are certain occurrences which are actually real but which science cannot explain because of their very nature. For example, if something can come into or out of existence at seemingly random times, how can it ever be tested scientifically? The random and unpredictable nature of it makes it practically impossible to test in a controlled setting. If I'm not mistaken, there are certain subatomic particles, called virtual particles, that are predicted by quantum theory as being able to pop in and out of existence. Pretty cool stuff.

If ghosts exist and they do pop in and out of existence then the physics laws which govern this are not known, assuming that such laws exist beyond it just being the whimsy of some ghost at work - which then implies the presence of consciousness on the part of the ghost. How could this ever be tested? It seems to be unfalsifiable. In science you can't test things that are unfalsifiable. It's like saying you have a friend who is invisible to everyone but you. Who can prove that wrong? No one can, but at the same time that's a far cry from proof that it's true.

It's important to be skeptical. Ghosts, unicorns, monsters, aliens, and all forms of paranormal claims all need solid proof of existence. Aliens are the only category mentioned that I have serious belief in the possibility of being true. But that's because humans are aliens too, from the perspective of life on other planets (if it exists), and it is likely to because our planet and its living conditions are far from being unique in the universe.

Until next time.


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