Flowing along in four dimensions

In 1988, John Cardy asked if there was a c-theorem in four dimensions. At the time, he reasonably expected his work on theories of quantum particles and fields to be professionally put to the test… But it never happened. Now – a quarter of a century later – it seems he was right.

“It is shown that, for d even, the one-point function of the trace of the stress tensor on the sphere, Sd, when suitably regularized, defines a c-function, which, at least to one loop order, is decreasing along RG trajectories and is stationary at RG fixed points, where it is proportional to the usual conformal anomaly.” said Cardy. “It is shown that the existence of such a c-function, if

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Want fuel cells? Think outside the hydrogen tank

When most people hear the words "fuel cell," they think of eco-friendly, hydrogen-powered cars that emit nothing more than water.

And that, says Professor Eric Wachsman, director of the University of Maryland Energy Research Center (UMERC), is one of the reasons we're all not driving one.

The U.S. Department of Energy's (DOE) recent decisions about how to fundfuel cell research, he says, are putting the country at risk of falling behind in the development and implementation of the most efficient means of converting fuel to electricity. Fuel cells have up to three times the efficiency of an internal combustion engine.

"There is a problem in the perception of the public and policy makers, and in the funding of our fuel cell

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Disconnect between wireless demand and capacity

A new report from the Global Information Industry Center at the University of California, San Diego examines the projected disconnect between U.S. wireless infrastructure capacity and consumer demand. According to “Point of View: Wireless Point of Disconnect,” wireless use is growing rapidly and if present trends continue, demand will often outstrip capacity, causing congestion.

“We’re currently experiencing a mass migration from wired networks towireless networks, which under the best of circumstances have far less capacity,” said Michael Kleeman, author of the report and senior fellow at UC San Diego. Wireless is much more convenient than wired connections for many purposes, but “we must understand and accept the trade-offs we will face for the convenience of accessing limited wireless capacity. Alternatively,

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Contested 'faster-than-light' experiment yields results

A fiercely contested experiment that appears to show the accepted speed limit of the Universe can be broken has yielded the same results in a re-run, European physicists said.

But counterparts in the United States said the experiment still did not resolve doubts and the Europeans themselves acknowledged this was not the end of the story.

On September 23, the European team issued a massive challenge tofundamental physics by saying they had measured particles called neutrinos which travelled around six kilometres (3.75 miles) per second faster than the velocity of light, determined by Einstein to be the highest speed possible.

The neutrinos had been measured along a 732-kilometre (454-mile) trajectory between the European Centre for Nuclear Research (CERN) in Switzerland

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High-tech robotic spider for hazardous missions

Spiders are very agile, and some can even jump. They owe this capability to their hydraulically operated limbs. Researchers have now designed a mobile robot modeled on the same principle that moves spider legs. Created using a 3-D printing process, this lightweight can explore terrain that is beyond human reach.

Enviably agile and purposeful, the mobile robot makes its way through grounds rendered off-limits to humans as the result of a chemical accident. Depressions, ruts and other obstacles are no match for this eight-legged high-tech journeyman. Its mission: with a camera and measurement equipment on board, it will provide emergency responders with an image of the situation on the ground, along with any data about poisonous substances. Not an easy

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Vast amounts of solar energy radiate to the Earth, but tapping it cost-effectively remains a challenge

With the world’s energy needs growing rapidly, can zero-carbon energy options be scaled up enough to make a significant difference? How much of a dent can these alternatives make in the world’s total energy usage over the next half-century? As the MIT Energy Initiative approaches its fifth anniversary next month, this five-part series takes a broad view of the likely scalable energy candidates.

The sunlight that reaches Earth every day dwarfs all the planet’s other energy sources. This solar energy is clearly sufficient in scale to meet all of mankind’s energy needs — if it can be harnessed and stored in a cost-effective way.

Unfortunately, that’s where the technology lags: Except in certain specific cases, solar energy is still too expensive to

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Google Maps taking viewers inside shops

Google's free online map service is letting shops, gyms, restaurants and other small businesses provide viewers glimpses of what lies behind facades seen on Street View.

A test program launched in April of last year was bearing fruit in a growing array of panoramic images taken inside businesses that volunteered to be part of the project.

"We've been seeing renewed interest in the past few days because, as promised, we're getting more imagery online," Google spokeswoman Deanna Yick told AFP on Monday.

"The 360-degree views are really visually engaging, so we're glad users are excited," she continued.

Small businesses in Japan, Australia, New Zealand, and the United States have been able to invite Street View photographers into their shops or eateries to capture images

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