photo: ‘Signs’/design: Antonio Manaligod for Dose

In ‘Signs,’ they prevented alien telepathy. But what about the NSA?

Our Movie Mythbusters series answers the age-old question, “Okay, but could that actually happen in real life?”

Before M. Night Shyamalan lost most of his Hollywood street cred, he released 2002’s alien thriller “Signs.” The movie (however poorly it’s aged) was a huge success at the time. I take no issue with the plausibility of crop circles, an alien invasion or the earth’s eventual salvation being — surprise, surprise — water. I’m more interested in those goofy tinfoil hats Joaquin Phoenix’s character and his kids don as makeshift defenses against the aliens’ telepathic intrusion.

Would a little metal chapeau do anything to guard against an extraterrestrial brain-assault? Or — keeping in mind the NSA’s enthusiasm for clandestine monitoring — the more pertinent question might be whether those caps would guard against governmental mind reading.

We can thank “Brave New World” author Aldous Huxley’s brother Julian for the concept of a tinfoil hat. In his 1927 short story “The Tissue-Culture King,” Julian wrote:

“Well, we had discovered that metal was relatively impervious to the telepathic effect, and had prepared for ourselves a sort of tin pulpit, behind which we could stand while conducting experiments. This, combined with caps of metal foil, enormously reduced the effects on ourselves.”

From there, tinfoil hats became synonymous with conspiracy theorists and paranoid kooks, particularly of the sci-fi variety. Turns out, however, the wackos might be doing the hat thing all wrong.

The general idea is that a tinfoil hat works as a Faraday Cage. These “cages” — invented in the 19th century by Michael Faraday — are shields that guard against different types of electrical interference. The Faraday website explains it like this:

“Faraday cages can be used to protect different kinds of electronic equipment from electrostatic discharges. They can’t block magnetic fields like Earth’s magnetic field, but they can protect the interior from electromagnetic radiation coming from the outside.”

Matt Soniak of The Atlantic points out that a tinfoil hat fails as a Faraday cage because it doesn’t fully enclose the wearer’s head. Assuming the aliens in “Signs” would use some sort of radio frequency to excise human thought, the tinfoil hats are pretty useless as a guard. Malevolent frequencies, according to Soniak, can still “get up underneath the brim and reveal your innermost thoughts.”

Soniak references an MIT experiment to determine the efficacy of tinfoil hats in deflecting potentially evil radio waves. Their conclusion? The aluminum headgear did deflect many known radio waves, but actually amplified those in the range which transmit mobile communications, broadcast satellites (for TV) and flight navigation.

In other words? Those protective caps are actually giant antennae allowing any manner of alien (or government) to invade your brain. Go figure.