Building an 'Invisibility Cloak' With Electromagnetic Fields 71
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.)"
Just as I thought! (Score:5, Insightful)
I wish they'd stop calling it that. (Score:5, Insightful)
Re:Error, Error. (Score:4, Insightful)
Sure, pragmatic constraints affect every design. But if you're worried about being spotted by cosmic rays, that's a lot better than being worried about being spotted by guards or radar.
Re:Error, Error. (Score:4, Insightful)
"Invisibility cloaks like this only work within a certain range of EM frequencies. "
Just like a concrete or brick wall. It works only within a certain range of EM frequencies.
With the right viewing system, you can see right through.
Invisibility Cloak, yeah right (Score:4, Insightful)
And I thought it was just the mayor smoking crack, apparently the whole town is now. :)