Light speed hurdle to invisibility cloak overcome by undergraduate

Aug 09, 2011

(PhysOrg.com) -- An undergraduate student has overcome a major hurdle in the development of invisibility cloaks by adding an optical device into their design that not only remains invisible itself, but also has the ability to slow down light.

The , known as an 'invisible sphere', would slow down all of the light that approaches a potential cloak, meaning that the light rays would not need to be accelerated around the cloaked objects at great speeds ― a requirement that has limited invisibility cloaks to work only in a specified region of the visible spectrum.

This new research, published today, Tuesday 9 August, in the Institute of Physics and German Physical Society's New Journal of Physics, could open up the possibility for a potential invisibility cloak wearer to move around amongst ever-changing backgrounds of a variety of colours.

Under the guidance of Professor Ulf Leonhardt, Janos Perczel, originating from Hungary and reading Logic, Philosophy of Science and Physics at the University of St Andrews, acknowledged the huge potential of the invisible sphere and was able to fine-tune it so that it was a suitable background for cloaking.

The usual approach to designing an works on the basis of bending light ― using highly specific materials ― around an object that you wish to conceal, thereby preventing the light from hitting the object and revealing its presence to the eye of the observer.

When the light is bent, it engulfs the object, much like water covering a rock sitting in a river bed, and carries on its path making it seem as if nothing is there.

Light, however, can only be accelerated to a speed faster than it would travel in space under certain conditions, and this restricts invisibility cloaks to work in a limited part of the spectrum ― essentially just one colour.

This would be ideal if somebody was planning to stand still in camouflage; however, the moment that they start to move the scenery will begin to distort, revealing the person under the cloak.

By slowing all of the light down with an invisible sphere, it does not need to be accelerated to such high speeds and can therefore work in all parts of the spectrum.

Perczel said, "I started to work on the problem of superluminal propagation as Professor Leonhardt's summer student with an EPSRC grant. Once the idea was present, I worked for over eight months to overcome the technical barriers and to make the proposal practicable."

An Institute of Physics spokesperson said, "This new development opens up further possibilities for the design of a practical invisibility ― overcoming the problem of speed that other advances have struggled to address and, very impressively, this significant advance was achieved by an undergraduate student."

Explore further: Halting photons could lead to miniature particle accelerators, improved data transmission

More information: New J. Phys. 13 (2011) 083007 doi:10.1088/1367-2630/13/8/083007

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User comments : 30

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Isaacsname
3 / 5 (2) Aug 09, 2011
That's impressive.
Sancho
3.3 / 5 (3) Aug 09, 2011
Can anyone suggest a use for a perfected invisibility cloak which is not criminal? (I include police/military actions which violate the Constitution as "criminal").
gottr
1 / 5 (3) Aug 09, 2011
Time travel.
AceLepage
5 / 5 (2) Aug 09, 2011
I believe it was suggested in a prior article. Create a thin tube that is cloaked. Insert wires into the tube and an LED at the end. You will not be able to see the wires, only the LED. Arrange the LEDs into a cubic grid, and you have a holographic display.
Techno1
1 / 5 (1) Aug 09, 2011
Can anyone suggest a use for a perfected invisibility cloak which is not criminal? (I include police/military actions which violate the Constitution as "criminal").


Nope. Unfortunately, this is one case where an invention/discovery will almost certainly benefit criminals and terrorists more in the long term.

Although making an invisible listening device may help governments spy on the spies and terrorists...
d_robison
4.5 / 5 (2) Aug 09, 2011
Can anyone suggest a use for a perfected invisibility cloak which is not criminal? (I include police/military actions which violate the Constitution as "criminal").


A very specific example would be possibly ending a hostage situation without anyone being harmed. That is the only thing I can think of that would be a non-criminal and constitutional use of a visible spectrum invisibility device.
GTMoneyMan
5 / 5 (8) Aug 09, 2011
Can anyone suggest a use for a perfected invisibility cloak which is not criminal? (I include police/military actions which violate the Constitution as "criminal").


Most would be, though military use against non-domestic threats would not be unconstitutional, but to expand to peaceful and non-criminal:

Disregarding cost and energy req., non-criminal uses could include cloaking unwanted items/buildings in a movie or TV set. Scientific observation of wildlife (though sound and smell would likely need to be cloaked as well). Hiding your GPS in your car from criminal elements who would steal it. Keeping that unsightly lamp your mother-in-law gave you from view of friends, but turn off the device when she visits. Thwart an eclipse. Find out what's on the other side of the sun. Hide view blocking support columns at stadiums. Hide your adult literature from your children. Pull a "Bilbo" on your 111th birthday.
skicreature
5 / 5 (2) Aug 09, 2011
Can anyone suggest a use for a perfected invisibility cloak which is not criminal? (I include police/military actions which violate the Constitution as "criminal").

Actually the greatest applications of these invisibility cloaks will be nowhere near the realm of military applications. They greatest benefits will come in the technology world with how the can advance optical computing for example. But i am sure there many greater applications that are still to be thought of. I believe IF this is used for military camouflage that will still be one of the smallest applications... I'm pretty sure there are much easier and simpler and CHEAPER ways for criminals to be successful without buying an invisibility cloak.
bluehigh
1 / 5 (3) Aug 09, 2011
whenever someone proposes photons having
superluminal propagation
- my bullshit detector raises an alarm.

Isaacsname
5 / 5 (2) Aug 09, 2011
Can anyone suggest a use for a perfected invisibility cloak which is not criminal? (I include police/military actions which violate the Constitution as "criminal").

Sure, right off the top of my head I could think of: Biologists, primate researchers, ornithologists , etc. they could do field studies in a whole new way.

Wife begging you to get rid of the rusty 74' Pinto in the backyard ?

..there you go.

MentalHealthNut
4 / 5 (4) Aug 09, 2011
Can anyone suggest a use for a perfected invisibility cloak which is not criminal? (I include police/military actions which violate the Constitution as "criminal").

Yes, it may be used for sneaking around Hogwarts to fight the evil forces of Voldemort.
Sparky11
5 / 5 (2) Aug 09, 2011
Can anyone suggest a use for a perfected invisibility cloak which is not criminal? (I include police/military actions which violate the Constitution as "criminal").

Sure, anything you don't want to see such as urban eyesores like antennas, electrical stations, power plants, etc. etc.
bigboymccoy
2.3 / 5 (3) Aug 09, 2011
"Light, however, can only be accelerated to a speed faster than it would travel in space under certain conditions, and this restricts invisibility cloaks to work in a limited part of the spectrum"

How can you accelerate light faster than it's speed in a vacuum? I smell BS.
jimbo92107
5 / 5 (3) Aug 09, 2011
You could scare the heck out of your cat with one of these things. Isn't that the main reason for inventing stuff?
Royale
3 / 5 (2) Aug 09, 2011
Well, scaring and/or entertaining cats jimbo.

And bigboy, I didn't notice them mention vacuum anywhere. Regardless, this breakthrough doesn't speed up light. It thwarts the problem. It is slowing down light, but equally in all directions. Perhaps you stopped paying attention when your BS detector went off? (As I occasionally do.)
SincerelyTwo
1.3 / 5 (4) Aug 09, 2011
Retards; Please try to remember that the people writing these articles are not physicists and frequently misinterpret what they read and are told.

Just because an individual who is reporting on some subject lies doesn't mean that lie exists within the subject itself.
Dichotomy
5 / 5 (1) Aug 09, 2011
Hey! I'm not a physicist and I think its pretty funny. Non criminal uses could also include:
-hiding things from other such as random obstacles and car keys
-individual's security (its hard to harm a person you can't see)
-seeing through things with poor visibility such as certain vehicles
-windowless windows

And who knows what else. For the person who mentioned scaring the cat, the windowless window is hysterical when the cat decides to attack something "outside" :)
eachus
4.8 / 5 (4) Aug 09, 2011
If I were designing a spaceship, an invisibility cloak that can work in the ultraviolet to gamma ray spectrum would be a wonderful addition. Drastically cut the amount of shielding needed, and cut the radiation dose to astronauts way below unshielded designs.

It would be nice to have something to deal with cosmic rays too, but they are really atoms. However, getting rid of the shielding for ordinary radiation reduces the secondary radiation from the cosmic rays. Can something deal with cosmic rays? Good question. They can be deflected with magnetic fields, but it is difficult to design a magnetic shield that is effective against cosmic rays from every direction. Very useful to have though, if you are visiting the vicinity of a black hole or neutron star.
ZachB
5 / 5 (1) Aug 09, 2011
Can anyone suggest a use for a perfected invisibility cloak which is not criminal? (I include police/military actions which violate the Constitution as "criminal").
Is hunting people with shoulder mounted rail guns in uncharted regions of South America strictly speaking "illegal"?
typicalguy
5 / 5 (5) Aug 09, 2011
Before I believe this, I need a better explanation than the words 'sphere of invisibility' because that sounds like something a dwarf may loot from a chest in a dungeons and dragons game.
maccaroo
5 / 5 (1) Aug 09, 2011
Sounds impressive, but the article makes no mention of how the device actually does anything. How does it bend the light around itself? Will it also bend other energy / matter which comes near it?
jibbles
not rated yet Aug 09, 2011
here's an application for cloaking that may be close to viable (because it's in the radio/microwave range so it's not nano): cloaking wind farms from weather/air traffic radar. there is a proposed windfarm project in the pacific northwest that's got a nearby military installation worried about interference.
DarkHorse66
not rated yet Aug 09, 2011
Alert: I see the advert spammers are back. Have just reported "minan"!!! For people trying to use this site as a 'point of sale', forget it! We come here to keep up with science and its progress; not to buy (most likely)fake brand name products.

ABUSERS!!!!!!!!!!!!!!!!!!!!
Vendicar_Decarian
5 / 5 (1) Aug 10, 2011
"This would be ideal if somebody was planning to stand still in camouflage; however, the moment that they start to move the scenery will begin to distort, revealing the person under the cloak." - Article

Klingon ships have that problem too and they still find their cloaks to be useful. The federation thinks so too since they sent Kirk and Spock on a secret mission to steal one.

bluehigh
1 / 5 (2) Aug 10, 2011
off topic but reminds me of when a science mag asked a star trek producer "how do the inertial dampers work"

"very well, thank you" was the reply.
krundoloss
not rated yet Aug 10, 2011
The most useful purpose of an invisibility cloak is to hide in the womens locker room.

And of course you can do some Navy Seal stuff.
hush1
3 / 5 (2) Aug 10, 2011
A new wave of treatment centers for kids.
(Having never found the eggs at Easter)
antialias_physorg
not rated yet Aug 15, 2011
Can anyone suggest a use for a perfected invisibility cloak which is not criminal?

Photon-based computers where individual elements are 'in the way' of the optic path.

In another article the cloaking effect applied to a liquid is proposed for reducing drag. There could be applications here for preventing soil erosion, making subaquatic structures safe from tsunamis, shielding spacecraft from hard radiation, ...

The possibilities are pretty wide ranging if you think about it.
Magnette
not rated yet Aug 16, 2011
"Can anyone suggest a use for a perfected invisibility cloak which is not criminal?"

It'll give the magicians and illusionists of the world a whole new range of possibilities.
antialias_physorg
not rated yet Aug 16, 2011
"Can anyone suggest a use for a perfected invisibility cloak which is not criminal?"


For everyday use: Street corners.
How neat would it be if buildings wouldn't obstruct the view? Big safety application right there.

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