Invisibility Technology: The Science of Hiding Light, Heat, and Sound

By Ahnaf Ahmed Prinon | 2025-07-16 11:08:45

Scientists around the world are trying to create technology that will keep us out of sight. But are we really that close to becoming invisible?
The desire to be invisible is very old. Hunters and soldiers have been using various techniques to hide themselves for centuries, but now scientists are getting closer to making some things truly invisible. Today's modern stealth technology can not only hide planes from radar, but can also hide heat signatures seen by infrared cameras, and even hide sound. So how close is the technology of invisibility?

The scientific basis of invisibility
We see an object because when light falls on that object, it is partly absorbed and partly reflected. But transparent objects like glass allow light to pass through almost unhindered. But if we want to hide an opaque object, then the light has to be directed around the object, as if it were nothing there!
In 2006, engineers at Duke University created the first cloaking device. It was a copper cylinder that was surrounded by microwaves, making it invisible to microwave detectors. The device was made of metamaterials—a type of special structure that is arranged in a three-dimensional pattern over and over again. As a result, it has some unusual properties.
However, this cloak only worked in microwaves—which are relatively large waves. But it is much more difficult to become invisible in visible light (which has much smaller waves). On the one hand, quantum effects come into play at the nano-scale, and on the other hand, it is very difficult to rotate all colors of light together. There was another big problem—this cloak only worked for a small object, not for something as large as a person.

Metalens: Precise control of light
In 2018, researchers from Harvard and the University of Waterloo in Canada created a sophisticated device, known as a metalens. A metalens is essentially a type of ultra-thin and flat lens, which looks almost like a thin glass disc, but its function is much more complex.