PARIS // Scientists in the US reported a further step towards a celebrated "invisibility cloak" by masking a large, free-standing object in three dimensions.
The laboratory work is the latest advance in a scientific frontier that uses novel materials to manipulate light, a trick that is of interest to the military in particular.
Reporting in the New Journal of Physics, researchers at the University of Texas in Austin cloaked an 18-centimetre cylindrical tube from light in the microwave part of the energy spectrum.
Those hoping for a Harry Potter-style touch of wizardry would be disappointed. To the human eye, which can perceive light only in higher frequencies, no invisibility would have been seen.
But, said the researchers, the experiment is important proof of a principle that so-called plasmonic meta-materials can achieve a cloaking effect.
A warplane cloaked with such materials could achieve "super-stealth" status by becoming invisible in all directions to radar microwaves, said the co-lead investigator Andrea Alu.
Plasmonic meta-materials are composites of metal and non-conductive synthetics made of nanometre-sized structures that are far smaller than the wavelength of the light that strikes them.
As a result, when incoming photons hit the material, they excite currents that make the light waves scatter.
The new experiment entailed making a shell of plasmonic meta-materials and placing the cylinder inside, and exposing the combination to microwaves.
Microwaves scattered by the shell ran into microwaves bounced from the object, preventing them from sending a return signal to the viewer.
"When the scattered fields from the cloak and the object interfere, they cancel each other out, and the overall effect is transparency and invisibility at all angles of observations," said Mr Alu.
Any shape of object can be masked, he added.
The cloaking worked best at a microwave frequency of 3.1 gigahertz, said the paper.
The feat is a step forward because other techniques have entailed bending light around two-dimensional objects or, in 3D, masking microscopic bumps on mirrors or reflectors, an approach called "carpet cloaking", said the authors.
The new concept could be modified for visible light, although any cloaked objects would be very small, in the micrometer range, as the plasmonic effect is linked to the wavelength of the light, Mr Alu said in an interview.
Even so, there could be important applications for microwave meta-materials, he said.
"What we are thinking about is not necessarily cloaking the whole warplane but some hot spots, a part such as the tailplane that you would want to cloak because it reflects most of the energy [from microwave radar]."
* Agence France-Presse
Other must-tries
Tomato and walnut salad
A lesson in simple, seasonal eating. Wedges of tomato, chunks of cucumber, thinly sliced red onion, coriander or parsley leaves, and perhaps some fresh dill are drizzled with a crushed walnut and garlic dressing. Do consider yourself warned: if you eat this salad in Georgia during the summer months, the tomatoes will be so ripe and flavourful that every tomato you eat from that day forth will taste lacklustre in comparison.
Badrijani nigvzit
A delicious vegetarian snack or starter. It consists of thinly sliced, fried then cooled aubergine smothered with a thick and creamy walnut sauce and folded or rolled. Take note, even though it seems like you should be able to pick these morsels up with your hands, they’re not as durable as they look. A knife and fork is the way to go.
Pkhali
This healthy little dish (a nice antidote to the khachapuri) is usually made with steamed then chopped cabbage, spinach, beetroot or green beans, combined with walnuts, garlic and herbs to make a vegetable pâté or paste. The mix is then often formed into rounds, chilled in the fridge and topped with pomegranate seeds before being served.
The smuggler
Eldarir had arrived at JFK in January 2020 with three suitcases, containing goods he valued at $300, when he was directed to a search area.
Officers found 41 gold artefacts among the bags, including amulets from a funerary set which prepared the deceased for the afterlife.
Also found was a cartouche of a Ptolemaic king on a relief that was originally part of a royal building or temple.
The largest single group of items found in Eldarir’s cases were 400 shabtis, or figurines.
Khouli conviction
Khouli smuggled items into the US by making false declarations to customs about the country of origin and value of the items.
According to Immigration and Customs Enforcement, he provided “false provenances which stated that [two] Egyptian antiquities were part of a collection assembled by Khouli's father in Israel in the 1960s” when in fact “Khouli acquired the Egyptian antiquities from other dealers”.
He was sentenced to one year of probation, six months of home confinement and 200 hours of community service in 2012 after admitting buying and smuggling Egyptian antiquities, including coffins, funerary boats and limestone figures.
For sale
A number of other items said to come from the collection of Ezeldeen Taha Eldarir are currently or recently for sale.
Their provenance is described in near identical terms as the British Museum shabti: bought from Salahaddin Sirmali, "authenticated and appraised" by Hossen Rashed, then imported to the US in 1948.
- An Egyptian Mummy mask dating from 700BC-30BC, is on offer for £11,807 ($15,275) online by a seller in Mexico
- A coffin lid dating back to 664BC-332BC was offered for sale by a Colorado-based art dealer, with a starting price of $65,000
- A shabti that was on sale through a Chicago-based coin dealer, dating from 1567BC-1085BC, is up for $1,950
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Key products and UAE prices
iPhone XS
With a 5.8-inch screen, it will be an advance version of the iPhone X. It will be dual sim and comes with better battery life, a faster processor and better camera. A new gold colour will be available.
Price: Dh4,229
iPhone XS Max
It is expected to be a grander version of the iPhone X with a 6.5-inch screen; an inch bigger than the screen of the iPhone 8 Plus.
Price: Dh4,649
iPhone XR
A low-cost version of the iPhone X with a 6.1-inch screen, it is expected to attract mass attention. According to industry experts, it is likely to have aluminium edges instead of stainless steel.
Price: Dh3,179
Apple Watch Series 4
More comprehensive health device with edge-to-edge displays that are more than 30 per cent bigger than displays on current models.
Paatal Lok season two
Directors: Avinash Arun, Prosit Roy
Stars: Jaideep Ahlawat, Ishwak Singh, Lc Sekhose, Merenla Imsong
Rating: 4.5/5
Background: Chemical Weapons
DMZ facts
- The DMZ was created as a buffer after the 1950-53 Korean War.
- It runs 248 kilometers across the Korean Peninsula and is 4km wide.
- The zone is jointly overseen by the US-led United Nations Command and North Korea.
- It is littered with an estimated 2 million mines, tank traps, razor wire fences and guard posts.
- Donald Trump and Kim Jong-Un met at a building in Panmunjom, where an armistice was signed to stop the Korean War.
- Panmunjom is 52km north of the Korean capital Seoul and 147km south of Pyongyang, North Korea’s capital.
- Former US president Bill Clinton visited Panmunjom in 1993, while Ronald Reagan visited the DMZ in 1983, George W. Bush in 2002 and Barack Obama visited a nearby military camp in 2012.
- Mr Trump planned to visit in November 2017, but heavy fog that prevented his helicopter from landing.
House-hunting
Top 10 locations for inquiries from US house hunters, according to Rightmove
- Edinburgh, Scotland
- Westminster, London
- Camden, London
- Glasgow, Scotland
- Islington, London
- Kensington and Chelsea, London
- Highlands, Scotland
- Argyll and Bute, Scotland
- Fife, Scotland
- Tower Hamlets, London
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