Slashdot Mirror
Building an 'Invisibility Cloak' With Electromagnetic Fields
Nerval's Lobster writes "University of Toronto researchers have demonstrated an invisibility cloak that hides objects within an electromagnetic field, rather than swaddling it in meta-materials as other approaches require. Instead of covering an object completely in an opaque cloak that then mimics the appearance of empty air, the technique developed by university engineering Prof. George Eleftheriades and Ph.D. candidate Michael Selvanayagam makes objects invisible using the ability of electromagnetic fields to redirect or scatter waves of energy. The approach is similar to that of 'stealth' aircraft whose skin is made of material that absorbs the energy from radar systems and deflects the rest away from the radar detectors that sent them. Rather than scattering radio waves passively due to the shape of its exterior, however, the Toronto pair's 'cloak' deflects energy using an electromagnetic field projected by antennas that surround the object being hidden. Most of the proposals in a long list of 'invisibility cloaks' announced during the past few years actually conceal objects by covering them with an opaque blanket, which becomes 'invisible' by displaying an image of what the space it occupies would look like if neither the cloak nor the object it concealed were present. An invisibility cloak concealing an adolescent wizard hiding in a corner, for example, would display an image of the walls behind it in an effort to fool observers into thinking there was no young wizard present to block their view of the empty corner. 'We've taken an electrical engineering approach, but that's what we are excited about,' Eleftheriades said in a public announcement of the paper's publication. (The full text is available as a free PDF here.)"
Invisibility cloaks like this only work within a certain range of EM frequencies. Outside of that range, it won't work; in fact it may even amplify the signal and make it more obvious whatever is being cloaked. And there are some thing no amount of cloak can deal with. You can alter the optical properties of a thing, but if it's out-gassing several thousand degree plumes... you cannot mask the infra red signature of that. These new meta materials may help in communications, but I highly doubt they will ever be able to make large human-sized physical objects disappear to any current multi-sensor technology.
#fuckbeta #iamslashdot #dicemustdie
Canada is harbouring dissident Romulan scientists brought here by James T. Kirk (Canadian William Shatner).
I think it's only justified to call something an "invisibility cloak" when it does what people actually expect an invisibility cloak to do, that is, make things actually not visible. How about calling it a "stealth cloak" because that's what I imagine most people would associate with being invisible to a radar, as opposed to the naked eye.
Invisible : Invisible to Radar :: Edible : Edible by Sperm Whales
Magnetic Multiplexed Photon Phase Inversion?
What a redundant and poorly written summary.
I may be missing how this works, but it looks like they are driving a bunch of antennas to cancel the scattered radiation from an object in one direction. While this works, the trick is to know exactly what the input signal is and the react in time to cancel - something that can only work for very narrowband sources or sources where you know the input field (including its phase) in advance.
I don't see how this could work for radar or light.
http://en.wikipedia.org/wiki/Philadelphia_Experiment
I just don't see this working......
"File to fit, pound to insert, paint to match" - Aircraft Maintenance 101
Instead of trying to make something invisible (isn't that hyper-impossible anyway?), why don't we just put an SEP field over it?
And this isn't even an "invisiblity" shield-- what it is, is a radar-scattering device.
From the article, apparently it scatters an incident radar beam so that the backscattered part (the part that returns to the transmitter) is zero. Specifically, they "then carefully modulated the current on each element to modify the field such that it deflected microwaves aimed at an aluminum cylinder in every direction except back toward the source of the microwaves, where the object could be detected."
So the object isn't invisible at all, except to observers who are looking at it from exactly the direction of the illumination-- in all other directions, it reflects brightly.
Furthermore, who the heck wrote this sentence: "using the ability of electromagnetic fields to redirect or scatter waves of energy." It is a feature of electromagnetic fields that they pass through each other (except in materials of strongly nonlinear index, of which air is not one.) You can't scatter one beam of light with another one!
http://www.geoffreylandis.com
Oh, wait... I guess the absence of pictures is proof that they succeeded. Bravo!
Koans and fables for the software engineer
Wasn't this already done with project rainbow ? I don't remember it working out to well for the sailors ;)
And I thought it was just the mayor smoking crack, apparently the whole town is now. :)
We have had this tech for over 40 years! Track Break Notch will do similar things by either walking a radar off you, or move your position according to what the radar can see.
The bigger problem is millimeter band radar, you need really funky waveguides to broadcast these as a normal antenna can't cope the small wave frequency.
The A6 from the Navy and the EF-111A from the USAF both could manage similar things to this, I can only hope they have managed to it smaller as the units for each section of bandwidth were the size of a small coffin, and you needed LOTS to cover the threat assessment for a given area.
Smells more like grant sniffing to me..
Good luck scattering and redirecting the rocks I start throwing in every direction once this technology is widely available.
I already have a more practical invisibility capability. I just talk to management about actual technical topics. I become invisible to them almost immediately.
Another Verge-esque Slashdot self-post... They need better topics breakdown for the "topical" slashdot.
Yet another link to an internal slashdot.org story under the datacenter topic... http://slashdot.org/topic/datacenter/invisibility-using-force-field-not-cloak/
Looks like slashdot is trying to be theverge or engadget...
I mean, didn't his cause havoc already?
:^S
For those of you asking "Why no picture" there actually is one.
1. go to google
3. type "empty field"
Tada, picture of an invisible car.
Sounds an awful lot like the Philadelphia Experiment except on a smaller scale. Not surprising that the work of Nikola Tesla,which in a lot of ways was way ahead of its time,is being re-examined.How many more of his discoveries will finally see the light of day after being suppressed for 60 or 70 years? All I can say is this -> "You Ain't seen Nothing Yet"
The Geek Hillbilly
The Klingons are going to be pissed we've got this technology too. Nothing quite as entertaining as a pissed-off Klingon, either.
I've fallen off your lawn, and I can't get up.
Seriously, the paper does not report on anything like visible light invisibility. That's not what this is. This is a case of misleading labelling.
will be a bizarre projector that came to him in a dream that will see right through that cloak.
It goes back to stealth technology in microwave region.
Canada's military snowmobile brigade can attack undetected