The Truth About The Science Of Invisibility
If you could turn yourself invisible, would you use your powers for good or evil? Be honest. If the imminent release of the latest film adaptation of H.G. Wells' The Invisible Man has you revisiting one of humanity's favorite hypothetical propositions, you're not alone. Interest in the real science of invisibility (yes, there's a real science of invisibility) has been spiking, so let's take a minute to examine what we know and where this previously science fictional field may be headed.
We've seen thousands of iterations of this trope on TV and in film. Whether it's James Bond's cloaking car, Harry Potter's invisibility cloak or the veritable pantheon of invisible superheroes, the ability to remain unseen has captured the imagination of some of our favorite storytellers. It's a strange law of our culture that where the storytellers go, the scientists often follow. While researchers haven't spent much time attempting to steal one of death's actual hallows, you might be surprised to find that (at least, where invisibility is concerned) the reality imitates the art in a few important ways.
Camouflage vs. transparency
James Bond's cloaking car, for example, uses an array of tiny cameras embedded in a projector skin that surrounds the car to help the vehicle blend into its surroundings. According to the New Scientist, this method of cloaking is feasible given current technology, though it provides a kind of imperfect camouflage rather than true invisibility. In Die Another Day, Q acknowledges this deficiency when he introduces Bond to the infamous Aston Martin V12 Vanquish. Similarly, the titular Invisible Man in the new Elisabeth Moss flick uses a similar pseudo-scientific method to achieve invisibility, without acknowledging the actually-scientific limitations noted in Bond.
When it comes to true transparency (rather than camera-assisted camouflage), the best science has to offer is much closer the wizarding methods employed by Harry Potter. Research published back in 2017 showed how researchers might make objects completely invisible using a kind of light-scattering invisibility cloak. It's currently difficult for materials scientists to cloak an object from more than one wavelength of light at a time, but these developments show that it's certainly possible to maintain invisibility within a certain band of the electromagnetic spectrum.
The future is transparent
Although this might sound like a very limited scope of invisibility, there is reason for optimism. The team responsible for creating the invisibility cloak specified that the wavelength limitations only apply for passive cloaking materials — that is: materials that don't require a net input of external energy. Add an external energy source to the equation, and the limitations no longer apply.
Andrea Alu, a researcher working on the project, articulated the challenge of creating true invisibility at the macroscopic level, "Even with active cloaks, Einstein's theory of relativity fundamentally limits the ultimate performance for invisibility. Yet, with new concepts and designs, such as active and nonlinear metamaterials, it is possible to move forward in the quest for transparency." Until we get there, mischief managed.