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Invisibility would be an awesome superpower. Are you socially avoidant? Just throw on your handy invisibility cloak and you’re good to go! And maybe you don’t want to hide. Maybe you just want to conceal your peanut butter so your flatmates will stop stealing it. What does science have to say about invisibility? A lot, as usual!

To understand how to not see something, you first need to understand a bit about how you see it. Light is radiation, produced by lots of different chemical reactions and when hydrogen atoms slam together in the sun (which is called nuclear fusion). When light reaches an object, there are three things that can happen: it can be reflected, absorbed or simply pass on through. We see things when reflected light enters our eyes.

But there is more to light than what meets the eye. The light humans can see – the reds, blues and greens that make up our world – constitute only a small part of what is called the electromagnetic spectrum. This spectrum ranges from the long wavelengths of radio waves, to microwaves, infrared radiation, visible light, ultraviolet light, x-rays and finally the short wavelengths of gamma rays.

So how do you make an object invisible? Well, you just need to “bend” light around it! That way the object won’t reflect any light and you won’t be able to see it. To achieve feats like this, scientists have created “metamaterials.” Metamaterials are materials that have been specifically engineered to have amazing properties, such as being able to deflect electromagnetic radiation around objects. This is given the cool name of “metamaterial cloaking.”

Microwaves are waves of radiation with applications in cell phones, wireless Internet and radar systems. To make something invisible to microwaves would make it undetectable by radar. Using metamaterials, scientists have been able to steer microwaves around small objects. As we can’t see microwaves, this doesn’t make the object invisible to us. But since microwaves, like visible light, are part of the electromagnetic spectrum, it is a step in the right direction. The challenge is to extend the technique to larger objects, and also the higher frequencies of visible light, which requires the metamaterial to be made out of smaller components.

Does this mean science can’t yet make anything disappear from view? Nope! Chinese scientists recently built a kind of invisibility cloak out of nothing other than a type of glass. The cloak looks like a simple glass container but has the ability to direct light around it in such a way that light reflected from directly behind the cloak reaches our eyes as if it passed straight through it. The scientists used this to render a cat invisible. When the cat jumped inside the cloak you could see through the cloak to a wall without seeing the enclosed cat. However, it is again early days. Disadvantages include the weight and fixed shape of the prism (as opposed to the soft, flexible cloaks favoured in science fiction). You wouldn’t exactly want to throw this on your cat. Another thing is that its effectiveness depends on the position of the viewer, with the cat not being invisible from all angles. This is quite a serious drawback if you want to put your invisibility cloak to practical use.