nother day, another invisibility cloak. Only this one is special because it can reportedly mask the appearance of time.
What does that even mean? It might be helpful to imagine the bus-scene gimmick in Speed in which the cops use a short loop of camera footage of all the passengers sitting still to fool Dennis Hopper into thinking everything is going his way, when in actuality, Keanu Reeves is helping everyone escape. The invisibility cloak illusion is kind of like that.
The cloaking technique, created by scientists at Purdue University, manipulates the speed of light in optical fibers to create what is ostensibly a gap in time in which any activity is left undetected, BBC News reports. If you wove enough of these fibers together into a cloak, you could theoretically rob a bank or pick your nose, and it'd be as if nothing was happening to anyone around you.
Up until now, other invisibility cloaks have worked using special metamaterials to bend light in unnatural ways around stationary objects, effectively masking them from view (or from sound waves or microwaves). The cloaking technology here is a bit different, and uses inverse waves to push and pull the light to make it appear as if things are business as usual, when in actuality there is a whole lot of activity going on.
"When one sends high-speed data over an optical fiber in the existing infrastructure, in many cases it's just 1s and 0s (binary code)," co-author Andrew Weiner tells BBC News. Manipulating the stream of light to create little holes in time is analogous to controlling the flow of a streaming river:
"Think about taking a region of that river and pushing some of it forward, and some backwards so there are holes where there isn't any water. Maybe there's a dam, and we can pop the dam on and off very quickly, to somehow disturb or divert the water.
"If we part the water so it doesn't see the dam popping up and down, it isn't disturbed, and afterwards we can put the water back together so it looks like a nice calm river again.
"That's how we control the flow of the light. We're pushing it forward and backwards in time, so it avoids events that would otherwise disturb it," Prof Weiner explained. [BBC News]
The experiment is a proof of concept of a 2010 London study that first suggested a "space-time cloak" was mathematically feasible. It was theorized that a wave phenomenon that was first discovered by British inventor Henry Fox Talbot back in 1836 could be exploited to hide an event in time. Nature explains that when "a light wave passes through a series of parallel slits called a diffraction grating, it splits apart." Here's the technical explanation:
The rays emanating from the slits combine on the other side to create an intricate interference pattern of peaks and troughs. Talbot discovered that this pattern repeats at regular intervals, creating what is now known as a Talbot carpet. There is also a temporal version of this effect in which you manipulate light over time to generate regular periods with zero light intensity, says Lukens. Data can be then be hidden in these holes in time. [Nature]
Essentially, by speeding up the front half of a wave and slowing down the back, you can create a tiny temporal gap that's rendered undetectable. That sounds like a lot of work, but the whole process is incredibly fast: 36 trillionths of a second. Weiner and his colleagues were able to successfully cloak tiny bits of data in this stretchy time-pocket 46 percent of the time.
That said, seeing 54 percent of some sneaky cloaked guy strolling into a bank vault with a rucksack is probably still enough to tip off the authorities. Nevertheless, researchers are confident that this discovery can improve our lives in a number of ways, from foiling communications between criminal networks to alleviating traffic jams in data transmission. Faster internet may not be as cool as space-time invisibility. But it's a start.
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