Technology

WHILE true invisibility cloaks

may remain forever a dream, the

ability to vanish into an ethereal

ray of light is still on the cards.

A device that bends

microwaves around an object has

been shown to render it partially

invisible (New Scientist, 28 October

2006, p 29), but Min Qiu of the

Royal Institute of Technology in

Kista, Sweden, and colleagues

argue that total invisibility would

require the value of some of the

cloak’s key electrical and magnetic

properties to be infinitely large –

something that is impossible.

A more realistic goal is to

remove the part of the cloak where

the values should be infinitely

large. They have calculated that the

resulting cloak renders someone

entirely invisible and leaves only

a thin line of light in the object’s

place. The results will be published

in Physical Review Letters.

PEER-to-peer networks, touted as

the future of video distribution

on the internet, face a critical

problem: many users download

lots of data but refuse to repay the

compliment by uploading more

content for others to see. The

overall effect of this one-way

traffic, or “leeching”, is to slow

down everybody’s internet access.

Now researchers at Harvard

5.6times the speed of sound is the target for China’s hypersonic scramjet aero engines, according to senior Chinese engineers

A new way to harness wind energy may

take off now that computers have

learned to kite surf.

Experienced kite surfers know that

on a calm day they can maximise the

power they draw from the breeze by

flying their aerofoil-shaped kites

through the air in a figure of eight.

“The amount of energy you get from

the figure of eight is massive, easily

10 times what you get from just parking

the kite downwind,” says Allister Furey,

a roboticist and avid kite surfer at the

University of Sussex in the UK.

Researchers have been trying to use

high-flying kites tethered to turbines to

generate electricity: when the kites tug

on the lines this turns the turbine.

While the idea works well when the

wind blows consistently, the computers

controlling the kites run into trouble

when there are gusts of wind or lulls,

often leading to crashes.

Now Furey and his colleague Inman

Harvey have developed a neural

network that has learned to steer a kite

like a seasoned professional. First they

wrote 20 different software algorithms

and got each to fly simulated kites so

that they would pull as hard as possible

in a wind of 8 metres per second.

“At first they were like blindfolded

idiots – they would crash the kite in a

quarter-second,” says Inman. “But one

or two would crash it in a half-second.”

The algorithms that kept the kites

aloft longer were “bred” together and

after 200 generations they had not only

evolved the ability to fly the kites, but

had also developed the figure of eight

style. Better still, they could cope with

strong gusts and lulls in the wind.

FLY A KITE TO SAVE THE PLANET

University and at Delft University

of Technology in the Netherlands

have created a program, called

Tribler , that turns net bandwidth

into a commodity akin to a

currency. The idea? You can only

spend it if you earn it.

In Tribler, users have to

“earn” credit by uploading data

before they can “spend” it by

downloading. As well as ensuring

fair play on the part of users,

trading bandwidth in this way

could relieve traffic jams on the

net as online video proliferates.

A molecule that flips between two states without altering the way it binds to other

molecules could bring molecular computing closer to reality. Researchers at IBM’s

Zurich Research Laboratory applied a voltage across a naphthalocyanine molecule.

That changed the orientation of two of its hydrogen atoms, but not its overall shape

(Science, vol 317, p 1203). Removing the voltage prompted the atoms to switch back.

The latest version of Google Earth has a secret: it has a flight simulator program built

into it, allowing users to pilot a light aircraft or an F-16 fighter jet from any airport to

anywhere on the planet – with stunning views. The feature, so far unannounced by

Google, was discovered by Marco Gallotta of Cape Town, South Africa, who reveals

how the simulator works on his computer science blog (www.tinyurl.com/3cludv).

GIZMO

1. Broadband internet connection

2. Pay TV

3. Cellphone

4. Landline phone

HOOKED ON BROADBAND

Top four modes of communication that Brits

find the most indispensable

After an Alabama man was indicted on charges of selling stolen golf equipment worth more than $77,000 on eBay, the FBI has warned that its agents are posing as buyers in a bid to snare criminals who are selling stolen goods online (networkworld.com, 31 August)

“Thieves should know that investigators can surf websites too”

–Time to harvest all that energy–

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All that’s left is a

sliver of light

No overdrafts

on the internet

www.newscientist.com 8 September 2007 | NewScientist | 29

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