'Space-time cloak' to conceal events revealed in new study

Nov 16, 2010
This graphic shows the "space-time" cloak works. Credit: Imperial College London

(PhysOrg.com) -- The study, by researchers from Imperial College London, involves a new class of materials called metamaterials, which can be artificially engineered to distort light or sound waves. With conventional materials, light typically travels along a straight line, but with metamaterials, scientists can exploit a wealth of additional flexibility to create undetectable blind spots. By deflecting certain parts of the electromagnetic spectrum, an image can be altered or made to look like it has disappeared.

Previously, a team led by Professor Sir John Pendry at Imperial College London showed that metamaterials could be used to make an optical invisibility cloak. Now, a team led by Professor Martin McCall has mathematically extended the idea of a cloak that conceals objects to one that conceals events.

"Light normally slows down as it enters a material, but it is theoretically possible to manipulate the light rays so that some parts speed up and others slow down," says McCall, from the Department of Physics at Imperial College London. When light is 'opened up' in this way, rather than being curved in space, the leading half of the light speeds up and arrives before an event, whilst the trailing half is made to lag behind and arrives too late. The result is that for a brief period the event is not illuminated, and escapes detection. Once the concealed passage has been used, the cloak can then be 'closed' seamlessly.

Such a space-time cloak would open up a temporary corridor through which energy, information and matter could be manipulated or transported undetected. "If you had someone moving along the corridor, it would appear to a distant observer as if they had relocated instantaneously, creating the illusion of a Star-Trek transporter," says McCall. "So, theoretically, this person might be able to do something and you wouldn't notice!"

While using the spacetime cloak to make people move undetected is still science fiction, there are many serious applications for the new research, which was funded by the Engineering and Physical Sciences Research Council (EPSRC) and the Leverhulme Trust. Co-author Dr Paul Kinsler developed a proof of concept design using customised optical fibres, which would enable researchers to use the event cloak in signal processing and computing. A given data channel could for example be interrupted to perform a priority calculation on a parallel channel during the cloak operation. Afterwards, it would appear to external parts of the circuit as though the original channel had processed information continuously, so as to achieve 'interrupt-without-interrupt'.

Alberto Favaro, who also worked on the project, explains: "Imagine computer data moving down a channel to be like a highway full of cars. You want to have a pedestrian crossing without interrupting the traffic, so you slow down the cars that haven't reached the crossing, while the cars that are at or beyond the crossing get sped up, which creates a gap in the middle for the pedestrian to cross. Meanwhile an observer down the road would only see a steady stream of traffic." One issue that cropped up during their calculations was to speed up the transmitted data without violating the laws of relativity. Favaro solved this by devising a clever material whose properties varied in both space and time, allowing the cloak to be formed.

"We're sure that there are many other possibilities opened up by our introduction of the concept of the spacetime cloak,' says McCall, "but as it's still theoretical at this stage we still need to work out the concrete details for our proposed applications."

Metamaterials is an expanding field of science, with a vast array of potential uses, spanning defence, security, medicine, data transfer and computing. Many ordinary household devices that work using electromagnetic fields could be made more cheaply or to work at higher speeds. Metamaterials could also be used to control other types of waves as well as light, such as sound or water waves, opening up potential applications for protecting coastal or offshore installations, or even engineering buildings to withstand earthquake waves.

Explore further: NIST 'combs' the atmosphere to measure greenhouse gases

More information: Paper online: iopscience.iop.org/2040-8986/1… 240-8986_13_2_024003

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User comments : 12

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davaguco
5 / 5 (1) Nov 16, 2010
Wow.
Husky
3 / 5 (2) Nov 16, 2010
ok, and does this invisible threading free the cpu from the overhead of managing threads and thus gain speed of operation?
KwasniczJ
1 / 5 (1) Nov 16, 2010
..theoretically, this person might be able to do something and you wouldn't notice..
So, is it possible to separate the time clock effect from spatial clock? It would probably appear like fuzzy shape of the object blurred with quantum noise...
kevinrtrs
3.3 / 5 (3) Nov 16, 2010
We can be sure the military are taking a very hard look at this to make sure they don't miss the event of it becoming reality ;-)))
There will of course be ways to detect that a visibility cloak is in place - eg. using a spread spectrum LADAR to probe those frequencies that the cloak cannot respond to.
mattytheory
5 / 5 (10) Nov 16, 2010
^
WORDS ARE COMING OUT OF MY MOUTH!!!!!!!!!
jselin
5 / 5 (4) Nov 16, 2010
Except that if you do anything beyond a few pico or micro seconds depending on your distance from the light source you will cause an actual interupt in the light. I discovered this cloaking effect years ago... its called turning off the lights ;) If you didn't see it it didn't happen right? Same logic, you just kept the "corrodor" open too long. Heck, persistence of vision would offer you a longer window that this technique as the time of flight for the light would be far shorter than the shortest noticable interupt in light. I encourage you to read the article again before rating this comment.

I take this tone because the suggestion that you could cloak an event like somebody moving sideways suddenly is just sensationalistic. The real gem here is in the routing of telecommunications.
sender
not rated yet Nov 16, 2010
non-blinking optical propulsion should offer time-travel capabilities thanks to this assay
antialias_physorg
not rated yet Nov 17, 2010
I take this tone because the suggestion that you could cloak an event like somebody moving sideways suddenly is just sensationalistic


Well, depends on what materials you use (look up 'slow light' on wikipedia). The method in the article relies on light travelling through a medium since otherwise you wouldn't be able to 'speed it up'. Depending on the types of materials you use and the length of your propagation channel the amount of time you can keep the corridor open is pretty much endless.

Think about what kind of possibilities this gives for a man-in-the-middle attack on data transmissions where timing is essential.
Skeptic_Heretic
5 / 5 (1) Nov 17, 2010
Electro-magnetic fields could be so incredible if we discover all imaginable 8 billion synthesizers at all pentacle positive positions without a center of gravity.

^
WORDS ARE COMING OUT OF MY MOUTH!!!!!!!!!

You owe me a keyboard, good sir. This one has been befouled by a coffee spit-take.
panorama
5 / 5 (2) Nov 17, 2010
If you freeze a liguid or gas at the bottom of the ocean for one year you have a positive magnetic property without gass developing center of gravity

I was literally about to type the same exact phrase...get out of my head.
JES
not rated yet Nov 17, 2010
I wrote a few meaningful things awhile ago.....
syd
5 / 5 (1) Nov 17, 2010
The thing...................................when the invisibil...................................and can do many of t...................................much like a tunafis...................................digiridoo whilst an...................................that being my point!

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