Lost in science fiction: Ghostbusters

This time on Lost in Science Fiction, aka science in the movies, let’s turn to a classic.

Appropriately for our pre-Halloween theme, it’s Ghostbusters (1984), directed by Ivan Reitman (see, I told you he’d be back), and starring Bill Murray, Dan Aykroyd, Sigourney Weaver, Harold Ramis, Rick Moranis, Annie Potts, etc.

It might not sound like it, but I believe this is a great movie for science. To quote:

But is there any real science in Ghostbusters? Well, there are the proton packs, those portable particle accelerators they wore on their backs – remember “don’t cross the streams”?

Of course, they’re not terribly accurate – a real world proton accelerator (like, say, the Large Hadron Collider) would be far too big to carry on your back – but what’s really interesting is what they seem to do, which is to contain “negatively charged ectoplasmic entities”. Which, considering positive electrical charges attract negative charges, kind of makes sense.

That’s if you assume that these “ectoplasmic entities” are negatively charged; presumably they’re negative because they’re bad, in some way.

Ectoplasm, though, is a term first used in 1883 to describe a material supposedly excreted from the orifices of mediums in the Victorian era. You can see “ectoplasm” in a lot of spirit photographs from the time (needless to say, they were hoaxes, and mediums tend not to do that these days).

Another Victorian-era innovation referenced in the movie is the actual practice of ghostbusting, or “ghost hunting“. It’s still very popular today; perhaps too popular, as apparently police forces in the United Kingdom are being inundated with nuisance Freedom of Information requests from ghost hunters looking for any reports containing supernatural terms. Although there were far more complaints about ghost hunters than actual sightings of ghosts in at least one report, from Dyfed-Owes Police in Wales (PDF 30 KB).

Seemingly influenced by the movie is not only the concept of ghostbusting, but also the techniques they use. Many modern ghost hunters carry electromagnetic field detectors, very similar to the devices used by Dr Egon Spendler.

Why would people think ghosts generate electromagnetic fields? Considering ghosts could at best be described as “unknown to science”, it seems strange to use such a specific scientific technique. Although, ghost hunters do at least claim they find strong electric or magnetic fields in haunted locations…

Is it just the movie’s influence, or is something else going on? Could they be extrapolating from the fact that living organisms produce electromagnetic fields?

Intriguingly, there have been counter-suggestions that it could run the other way: that electromagnetic fields may cause people to see ghosts.

It’s been long known that strong electric or magnetic fields can cause people to see flashes of light, or phosphenes (PDF 8.4 MB). But even further than that, Canadian psychologist Michael Persinger claims that low-level magnetic fields applied to the temporal lobes of the brain can cause people to sense a mysterious presence, or even experience religious ecstasy. He’s even invented a device to generate this effect, called the God Helmet.

Persinger’s claims are very controversial, with critics saying that the power of suggestion, as well as prior susceptibility and beliefs, have far more to do with whether people experience any unexplained sensations under the influence of the God Helmet. At least, this seemed to be the case with the ‘Haunt’ Project, which attempted to use both electromagnetic fields and infrasonic (low frequency) sound to cause people to sense a ghostly presence (it didn’t work).

So perhaps a more likely explanation for the use of electromagnetic field detectors is that they’re essentially another data collecting device to take with you when hunting ghosts. And the more types of data you collect – preferably by using high-tech equipment that’s easy to misinterpret – the more likely it is that you’ll find something unusual purely by chance.

And when you’re casting a wide net for anomalies, anything you find takes on significance, no matter how random. Which is a mistake you often find in pseudoscience.

Still, it’s all very entertaining, and I’m possibly being too harsh on the ghost hunters. Maybe I should back off: they’re pseudoscientists.

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