For the myriad of ‘Harry Potter’ lovers out there, the day when science unveils a real-life invisibility cloak can’t come too soon. The good news is that that day could be on the radar, as discussions on the topic have opened up again. So, could invisible cloaks be within reach?
Few Past Attempts at an Invisibility Cloak
In 2011 scientists produced a cloak capable of modifying the behavior of light to conceal macroscopic objects. The cloak was made out of minutely holed layers of silicon nitride and silicon oxide which when combined were able to modify the speed at which light passed through onto the concealed object. The effect of this was that it appeared to the human eye that light never hit the object at all, rendering it invisible.
The cloak represented a leap forward in this technology, however, there were still problems. For one thing, the size of the object concealed was so small as to be essentially invisible to the naked eye in the first place, and the cloak’s originators said that even producing a cloak for this size took a full week and consisted of around 7,000 light-modifying holes. Using these figures, the time to produce a cloak big enough to conceal an average-sized human would be astronomically high.
Other cloaking concepts followed. One development employed the distorting properties of extreme temperature to hide objects by bending light rays away from the heat – like a super hot mirage effect. This too had problems.
The heat required to effectively render even a small object invisible was 2,500 degrees Kelvin – around 2227 degrees Celsius; hot enough to work underwater, but also hot enough to incinerate any self-respecting individual who opted for this stealth tactic, not to mention the extreme readings undoubtedly picked up by thermal cameras.
Recent Discussion
At present, engineers at Duke University claim that current cloaking devices represent “a tiny portion, at best” of the whole process. The biggest problem with using light-redirecting technology is that when light has to travel further distances it takes longer to reach the eye, resulting in an imperfect cloaking process.
However, at the speed at which technology is advancing these same engineers estimate that we will see vast improvements within the next hundred years – a comparatively short period when considering the obstacles to overcome. Even more exciting is the fact that once the technology is in place to be able to produce an effective device, we will likely also have technology able to replicate the method in sizes capable of concealing objects far bigger than humans.
So in the grand scheme of things, a working invisibility cloak isn’t all too unimaginable. The closest thing conceivable at present is the production of a suit made of hundreds of thousands of minute cameras that record surrounding scenery and relay it to cameras on the opposite side of the suit, resulting in the appearance of looking straight through the wearer. This of course cannot ensure 360-degree invisibility but the objects do disappear from the naked eye from certain angles.
In 2019, a Canadian company used a brand new technique called Quantam Stealth that bends the light away from a special sheet that allows an object to hide behind the sheet and be completely invisible in all environments.
Whilst you’re not going to be crept up on by invisible friends any time soon, it’s worth keeping an eye on developments… because they might not be visible to the human eye for that much longer.
