Physics proves horror movies get it wrong
Judy Skatssoon
ABC Science Online

Who needs ghostbusters when you've got Newton, says a scientist who has used physics and maths to poke holes in the way Hollywood depicts ghosts and vampires.

In a paper, published recently on the physics website arXiv, theoretical physicist Professor Costas Efthimiou of the University of Central Florida shows that when it comes to things supernatural, the figures just don't add up.

For instance, the ability to walk through walls is a common talent of celluloid ghosts.

But Newton's laws of physics suggest that if a ghost can walk it shouldn't be able to pass through walls, say Efthimiou and Cornell University postgraduate student Sohan Gandhi.

Newton says a body at rest will remain at rest until it's acted on by an external force and for every action there is an equal but opposite reaction.

So in order to walk, we apply a backward force on the floor with our feet, propelling the feet up and us forwards.

But if a ghost can walk through walls, it must be "material-less", the authors argue, and incapable of exerting force.

By the same token, a ghost that can walk through walls should also sink through the floor, and a ghost that can walk should be bouncing off the walls it tries to pass through.

"The depiction of ghosts walking contradicts the precept that ghosts are material-less," they write.

Ghostly chills

Sharp drops in temperature are also associated with the arrival of a ghost.

But the paper says physics, which suggests that a sense of cold is correlated more to the rate at which heat is transferred from bodies to the environment than actual temperature, can provide an explanation.

"It has become almost a Hollywood cliché that the entrance of a ghostly presence be foreshadowed by a sudden and overwhelming chill," they write.

"This feature of supposed ghost sightings lends itself naturally to physical explanation."

Efthimiou and Gandhi say when a warm object is placed next to a cold object, energy flows from the warm body to the cooler body, cooling the warm body.

In a room with a high window or a door with a gap, the cool air from outside displaces warm air inside, creating a system of heat cycles and eddies.

The effect is increased because humans are more sensitive to rapid changes in temperature even if the absolute change is small.

A 2001 UK investigation of the famous Haunted Gallery at Hampton Court, by the University of Hertfordshire's Dr Richard Wiseman, found that hidden doors were letting in draughts.

This produced a combination of air currents that caused temperatures to plummet up to 2°C in some parts, the paper says.

Blood suckers?

Efthimiou and Gandhi also use the mathematical principle of geometric progression to rule out the existence of vampires.

They argue it would take just two and a half years for vampires to wipe out the entire human race from the day the first one appeared, based on the myth that vampires turn their victims into other vampires by sucking their blood.

If vampires feed once a month, the great grandaddy of all vampires would have killed one human and produced one vampire in the first month. So in total there would be two vampires and one less human, or a tally of vampires 2, humans -1.

By the next month, the 2 vampires would kill 2 humans, and so on.

After n months there would be 2 x 2 x 2 ... x 2 = 2n, or a geometric progression with ratio 2.

"The vampire population increases geometrically and the human population decreases geometrically," they say.

Using the principle of reductio ad absurdum, they conclude that vampires can't exist as their existence contradicts the existence of humans.

Professor Alan Carey, dean of the Mathematical Sciences Institute at the Australian National University, says the paper successfully debunks the depictions of the supernatural in the movies.

"They poke holes in the clichés and mistakes that are made, and that's not too hard to do," he says.

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There was a little bit of discussion about this already in the Science forum: thread.

Interesting article. Of course, there are ways around physics *round and round we go - whee*

walking through walls - as a ghost, who's to say they don't ahve the ability to will themselves to move forward. Motion is not necessarily a sign of force.

temperature drop - interesting, need to consider more.

vampires - This is of course assuming that every vampire feeds (some might starve to death for whatever reason). Or there might just be some very dedicated vampire hunters out there. And of course, this doesn't take into account that the human race is also increasing in size, though obviously not doubling every month as the vampire would (assuming every vampire that sucks blood Turns their victim - many Vampire myths require the transference of blood from both the victim and the vampire, thus not all feeding-frenzies necessarily result in any new vampires).

Ok, sorry to spoil the article for ya's. Back to discussion

An object can not move unless a force is acting upon it.

Mind over matter, my friend. Science-fiction is great because you can make up rules as you go along to contravene what we know is "fact". a creature without form or substance may be able to control itself through willpower. Maybe a ghost is simply a form of life that realised the mortal coil is not necessary for "life"

Questionable. True, you could get around a physics critique of the movies by saying "well, maybe physics doesn't apply" but it seems a little weak.

Depends what kind of science-fiction you are talking about.
"Hard" science fiction attempts not to violate scientific law.
Other subgenres aka "the good stuff" pretty much do what ever they want.

Really? Some movies force you to suspend disbelief for the purpose of entertainment? Vampires DON'T exist? Wow! Thanks, science! EXCELSIOR!

When it comes to the paranormal, many do have trouble distinguishing between fiction and reality.

I thought ghosts were out of sync with this world, yet aware of it. making it possible for them to rest/walk on solid ground, yet walk through solid objects

Ooopsies thanks




examples of "hard" and "good stuff" please

Oh, God. Why you gotta tax my brain?
By author's tendencies:
Hard: Postulates what may be possible with existing technology, or that which is slightly in the future. Wikipedia entry here. Although I would disagree with some of the names on the list. The best of this genre is Ben Bova's 'Grand Tour' series. About the only hard science fiction I bother to read.
The Good Stuff: Screw Reality. Phillip K. Dick, Roger Zelazny, Harlan Ellison (Greatest short story ever: 'I Have No Mouth and I Must Scream' ), Frederik Pohl, Alfred Bester, Frank Herbert, Stephen R. Donaldson ("The Gap"), Aldous Huxley, Douglas Adams, Phillip Jose Farmer, Ray Bradbury...

And, -- PA cover your eyes -- there is actually a third subset of science fiction: sci-fi.
Pop culture garbage of questionable quality.
Basically every 'science fiction' show ever on television, with the exception of "The Twilight Zone."
Yes, I include 'Star Trek' in there. And yes, I know Harlan Ellison and Ray Bradbury wrote some episodes. But then again, they had to eat.
And pretty much everything on the cable channel of the same name.
Gives the real stuff, an important literary genre in it's own right, a bad name.
Nothing worse for science fiction's image than a Trekkie or Star Wars convention.
Somebody tell PA he can look again.

Yeah like someone would ever, ever find Sarah Jessica Parker attractive. That's a huge stretch of the imagination right there.

These guys would. But then again, she is one of their own.