Scientists are boldly going where only fiction has gone before -- to develop a "Cloak of Invisibility."
It is not quite ready to hide a Romulan space ship from Captain James T. Kirk of Star Trek or to disguise Harry Potter. But it is a significant start and could show the way to more sophisticated designs.
In this first successful experiment, researchers from the US and Britain were able to cloak a copper cylinder.
It is like a mirage, where heat causes the bending of light rays and cloaks the road ahead behind an image of the sky.
"We have built an artificial mirage that can hide something from would-be observers in any direction," said cloak designer David Schurig, a research associate in Duke University's electrical and computer engineering department.
For their first attempt, the researchers designed a cloak that prevents microwaves from detecting objects. Like light and radar waves, microwaves usually bounce off objects, making them visible to instruments and creating a shadow that can be detected.
The cloaking uses special materials to deflect radar or light or other waves around an object like water flowing around a smooth rock in a stream. It differs from stealth technology, which does not make an aircraft invisible but reduces the cross-section available to radar, making it hard to track.
The new work points the way for an improved version that could hide people and objects from visible light.
Conceptually, the chance of adapting the concept to visible light is good, Schurig said in a telephone interview. But, he added, "From an engineering point of view it is very challenging."
The cloaking of a cylinder from microwaves comes just five months after Schurig and colleagues published their theory that it should be possible. Their work was reported in a paper in yesterday's issue of the journal Science.
"We did this work very quickly ... and that led to a cloak that is not optimal," said co-author David Smith, also of Duke.
"We know how to make a much better one," he added.
The first working cloak was in only two dimensions and did cast a small shadow, Smith said.
The next step is to go for three dimensions and to eliminate any shadow.
Viewers can see things because objects scatter the light that strikes them, reflecting some of it back to the eye.
"The cloak reduces both an object's reflection and its shadow, either of which would enable its detection," Smith said.
The cloak is made of metamaterials, which are mixtures of metal and circuit board materials such as ceramic, Teflon or fiber composite.
In an ideal situation, the cloak and the item it is hiding would be invisible. An observer would see whatever is beyond them, with no evidence that the cloaked item exists.
PREPAREDNESS: Given the difficulty of importing ammunition during wartime, the Ministry of National Defense said it would prioritize ‘coproduction’ partnerships A newly formed unit of the Marine Corps tasked with land-based security operations has recently replaced its aging, domestically produced rifles with more advanced, US-made M4A1 rifles, a source said yesterday. The unnamed source familiar with the matter said the First Security Battalion of the Marine Corps’ Air Defense and Base Guard Group has replaced its older T65K2 rifles, which have been in service since the late 1980s, with the newly received M4A1s. The source did not say exactly when the upgrade took place or how many M4A1s were issued to the battalion. The confirmation came after Chinese-language media reported
A Ministry of Foreign Affairs official yesterday said that a delegation that visited China for an APEC meeting did not receive any kind of treatment that downgraded Taiwan’s sovereignty. Department of International Organizations Director-General Jonathan Sun (孫儉元) said that he and a group of ministry officials visited Shenzhen, China, to attend the APEC Informal Senior Officials’ Meeting last month. The trip went “smoothly and safely” for all Taiwanese delegates, as the Chinese side arranged the trip in accordance with long-standing practices, Sun said at the ministry’s weekly briefing. The Taiwanese group did not encounter any political suppression, he said. Sun made the remarks when
The Taiwanese passport ranked 33rd in a global listing of passports by convenience this month, rising three places from last month’s ranking, but matching its position in January last year. The Henley Passport Index, an international ranking of passports by the number of designations its holder can travel to without a visa, showed that the Taiwan passport enables holders to travel to 139 countries and territories without a visa. Singapore’s passport was ranked the most powerful with visa-free access to 192 destinations out of 227, according to the index published on Tuesday by UK-based migration investment consultancy firm Henley and Partners. Japan’s and
BROAD AGREEMENT: The two are nearing a trade deal to reduce Taiwan’s tariff to 15% and a commitment for TSMC to build five more fabs, a ‘New York Times’ report said Taiwan and the US have reached a broad consensus on a trade deal, the Executive Yuan’s Office of Trade Negotiations said yesterday, after a report said that Washington is set to reduce Taiwan’s tariff rate to 15 percent. The New York Times on Monday reported that the two nations are nearing a trade deal to reduce Taiwan’s tariff rate to 15 percent and commit Taiwan Semiconductor Manufacturing Co (TSMC, 台積電) to building at least five more facilities in the US. “The agreement, which has been under negotiation for months, is being legally scrubbed and could be announced this month,” the paper said,
RSS