Not all monsters can be explained. In horror movies especially, it's often better to keep them partially obscured, or, in the case of The Invisible Man, encased in a technologically advanced suit that renders the wearer completely unseeable. But while the movie wisely avoids getting too bogged down in technical explanations, Adrian Griffin's (Oliver Jackson-Cohen) Invisible Man invisibility suit has substantial real-world precedent.
Described as an "optics groundbreaker," Griffin is a controlling, sociopathic tech luminary, who uses his invisibility suit to torment Cecilia (Elisabeth Moss), the woman who refused to submit to his totalitarian nature. But she has a big problem: nobody but she believes that Adrian has figured out a way to be invisible.
It seems they haven't been paying attention to the research of physicist David R. Smith, professor of electrical and computing engineering at Duke University, who, alongside R.A. Shelby and S. Schultz, made the first experimental proof of a material with a negative index of refraction, opening the door to new "metamaterials" capable of creating what they described as "nonintuitive optics." It's an approach that may one day make invisibility possible.
The Road to Invisibility
The refractive index is a measure of how fast light travels through a material, visible as a "bend" in the light, such as the distortion observable in the appearance of objects half-submerged in water (through which light travels at approximately 75 percent of the speed it does through a vacuum). While all natural substances have a positive index of refraction, Soviet physicist Victor Viselago hypothesized the possibility of a negative index-of-refraction material in 1967.
"That really spawned the field of metamaterials, because you can have something that doesn't exist in nature," Smith told Newsweek. "No natural material has this property."
Smith built on practical approaches proposed by theoretical physicist Sir John Pendry to construct the first negative—or "left-handed"—material: a lattice of copper wire strips on circuit board that demonstrated inverted optical properties in response to a microwave beam.
In subsequent experiments, often in collaboration with Pendry, Smith demonstrated that microwave frequencies could be bent around an object and restored on the other side: a necessary prerequisite for true invisibility cloaking. But even before various experimental approaches on the road to invisibility fell into place, the implications of early research was obvious from the beginning.
"An immediate question is whether the negative index-of-refraction property can be implemented at optical frequencies," Smith and his co-authors wrote in their paper "Experimental Verification of a Negative Index of Refraction," published in the journal Science in 2001. After raising several obstacles to creating metamaterial capable of affecting the visual spectrum of light, they concluded, "the use of photonic crystals as negative refractive material is intriguing and may offer the means of extending the phenomenon we report here to optical wavelengths."
Smith and Pendry continued research into what came to be called "transformation optics," which develops metamaterials to distort or redirect the waves—or radiation—of electromagnetic fields, which include microwaves, infrared, X-rays, ultraviolet, radio and the visible spectrum of light. The new field of research captured the public imagination, by providing a rigorous theoretical approach to a possible "invisibility cloak."
"It's still a very, very difficult thing to do," Smith said. "There's a theoretical path, but it's still a very difficult path."
One obstacle is that visible light as we know it isn't a single wavelength, but is instead a band within the electromagnetic spectrum. So while a metamaterial may be designed to bend a certain wavelength around it, the narrowly tailored bandwidth would result in a cloak for a single color. An invisible man is going to need to more than just the color green to disappear if he hopes to terrorize the populace. Other optical experiments generate effects that would require the observer to stand still, another non-starter for the hopeful voyeur psychopath.
The Invisible Man Approach
Built of polygonal panels, each embedded with a camera lens, Griffin's invisibility suit seems to employ an approach to invisibility that relies more on brute force computation. Rather than bending light around, Griffin's suit acts like a hyperactive camouflage, by measuring incoming light and projecting it on the opposite side of his body, creating the illusion of invisibility.
"I think that's actually a reasonable approach, which is to fool the eye. So it wouldn't do a full electromagnetic thing, but it would take information about the surrounding and project it, like an advanced form of camouflage," Smith said, comparing this approach to a chameleon or cuttlefish, both animals that can sense their background and project those colors through chromatophore cells. But without hardware capable of performing this task instantly, this is more likely to create a blurry man than an invisible one, similar to the alien, game-hunting Predator.
But there's one tell In The Invisible Man that suggests Adrian Griffin took a hybrid approach, using both active camouflage and metamaterials: he doesn't cast a shadow. While there's no way to eliminate the shadow of someone wearing a mere camouflage suit, a true invisible man could use theoretical metamaterials to bend the light around him and reconstitute it on the other side.
Griffin's outrageously complex invisibility suit produces all new challenges ("In science fiction, power sources are easy to come by apparently," Smith quipped), but Smith found it more plausible than previous stories of invisible men.
"The H.G. Wells invisibility was based on something that would be like a chemical reaction," Smith said, alluding to the chemical cocktail taken by Griffin in the 1897 science fiction novel and its 1933 movie adaptation, which stars Claude Rains (Casablanca) as the titular mad scientist. "That's unlikely, because everything in your body works and has color for different reasons. Blood is red because it carries oxygen and has hemoglobin. If you made it invisible, your body would stop functioning."
How To Fight Back Against An Invisible Man
In The Invisible Man, Cecilia uses a variety of tactics to draw out the invisible Griffin, spreading coffee grounds on the floor to look for footprints, luring him out in the rain or splashing him with paint. Smith validated the approach.
"I would carry a can of paint and I'd whip it around," Smith said, further citing an episode of The Boys, in which Billy Butcher (Karl Urban) smears his own blood all over the invisible "hero" Translucent (Alex Hassell) to expose him.
"The only thing more brilliant than inventing something that makes you invisible is not inventing it, but making you think he did," Adrian's brother Tom (Michael Dorman), a lawyer who holds the purse strings over Cecilia's head, tells her in The Invisible Man. "Don't let him win by bringing him back to life."
Well, Tom's wrong, because it's going to take a lot more brilliance to bring about real invisibility.
So there's no point in stocking up on paint cans just yet, not only because of the practical obstacles to a wearable invisibility suit, but also because of more surprising practical applications for "transformation optics," which could make technological leaps far more imaginative than anything in The Invisible Man.
"I think it's useful to know that it's not all about invisibility," Smith said, emphasizing that metamaterials are already becoming big business, fueling advances in satellite communication and radar.
And there's lots more to come: "There was one thing I think was rather a big idea: which would be to cloak earthquakes; to redirect earthquake waves around to protect a structure. That actually has some feasibility. Acoustic waves are easier to cloak and manage than optical waves for various reasons."
Scientists and engineers are thinking bigger than Adrian Griffin and his monomaniacal obsession with bringing Cecilia under his thumb.
The Invisible Man is in theaters now.
Uncommon Knowledge
Newsweek is committed to challenging conventional wisdom and finding connections in the search for common ground.
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