Physicists have 'solved' mystery of levitation

Levitation has been elevated from being pure science fiction to science fact, according to a study reported today by physicists.

In theory the discovery could be used to levitate a person

In earlier work the same team of theoretical physicists showed that invisibility cloaks are feasible.

Now, in another report that sounds like it comes out of the pages of a Harry Potter book, the University of St Andrews team has created an 'incredible levitation effects’ by engineering the force of nature which normally causes objects to stick together.

Professor Ulf Leonhardt and Dr Thomas Philbin, from the University of St Andrews in Scotland, have worked out a way of reversing this pheneomenon, known as the Casimir force, so that it repels instead of attracts.

Their discovery could ultimately lead to frictionless micro-machines with moving parts that levitate But they say that, in principle at least, the same effect could be used to levitate bigger objects too, even a person.

The Casimir force is a consequence of quantum mechanics, the theory that describes the world of atoms and subatomic particles that is not only the most successful theory of physics but also the most baffling.

The force is due to neither electrical charge or gravity, for example, but the fluctuations in all-pervasive energy fields in the intervening empty space between the objects and is one reason atoms stick together, also explaining a “dry glue” effect that enables a gecko to walk across a ceiling.

Now, using a special lens of a kind that has already been built, Prof Ulf Leonhardt and Dr Thomas Philbin report in the New Journal of Physics they can engineer the Casimir force to repel, rather than attact.

Because the Casimir force causes problems for nanotechnologists, who are trying to build electrical circuits and tiny mechanical devices on silicon chips, among other things, the team believes the feat could initially be used to stop tiny objects from sticking to each other.

Prof Leonhardt explained, “The Casimir force is the ultimate cause of friction in the nano-world, in particular in some microelectromechanical systems.

Such systems already play an important role - for example tiny mechanical devices which triggers a car airbag to inflate or those which power tiny 'lab on chip’ devices used for drugs testing or chemical analysis.

Micro or nano machines could run smoother and with less or no friction at all if one can manipulate the force.” Though it is possible to levitate objects as big as humans, scientists are a long way off developing the technology for such feats, said Dr Philbin.

The practicalities of designing the lens to do this are daunting but not impossible and levitation “could happen over quite a distance”.

Prof Leonhardt leads one of four teams - three of them in Britain - to have put forward a theory in a peer-reviewed journal to achieve invisibility by making light waves flow around an object - just as a river flows undisturbed around a smooth rock.

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The Future Is Now? Pretty Soon, at Least

Before we get to Ray Kurzweil’s plan for upgrading the “suboptimal software” in your brain, let me pass on some of the cheery news he brought to the World Science Festival last week in New York.

Do you have trouble sticking to a diet? Have patience. Within 10 years, Dr. Kurzweil explained, there will be a drug that lets you eat whatever you want without gaining weight.

Worried about greenhouse gas emissions? Have faith. Solar power may look terribly uneconomical at the moment, but with the exponential progress being made in nanoengineering, Dr. Kurzweil calculates that it’ll be cost-competitive with fossil fuels in just five years, and that within 20 years all our energy will come from clean sources.

Are you depressed by the prospect of dying? Well, if you can hang on another 15 years, your life expectancy will keep rising every year faster than you’re aging. And then, before the century is even half over, you can be around for the Singularity, that revolutionary transition when humans and/or machines start evolving into immortal beings with ever-improving software.

At least that’s Dr. Kurzweil’s calculation. It may sound too good to be true, but even his critics acknowledge he’s not your ordinary sci-fi fantasist. He is a futurist with a track record and enough credibility for the National Academy of Engineering to publish his sunny forecast for solar energy.

He makes his predictions using what he calls the Law of Accelerating Returns, a concept he illustrated at the festival with a history of his own inventions for the blind. In 1976, when he pioneered a device that could scan books and read them aloud, it was the size of a washing machine.

Two decades ago he predicted that “early in the 21st century” blind people would be able to read anything anywhere using a handheld device. In 2002 he narrowed the arrival date to 2008. On Thursday night at the festival, he pulled out a new gadget the size of a cellphone, and when he pointed it at the brochure for the science festival, it had no trouble reading the text aloud.

This invention, Dr. Kurzweil said, was no harder to anticipate than some of the predictions he made in the late 1980s, like the explosive growth of the Internet in the 1990s and a computer chess champion by 1998. (He was off by a year — Deep Blue’s chess victory came in 1997.)

“Certain aspects of technology follow amazingly predictable trajectories,” he said, and showed a graph of computing power starting with the first electromechanical machines more than a century ago. At first the machines’ power doubled every three years; then in midcentury the doubling came every two years (the rate that inspired Moore’s Law); now it takes only about a year.

Dr. Kurzweil has other graphs showing a century of exponential growth in the number of patents issued, the spread of telephones, the money spent on education. One graph of technological changes goes back millions of years, starting with stone tools and accelerating through the development of agriculture, writing, the Industrial Revolution and computers. (For details, see nytimes.com/tierneylab.)

Now, he sees biology, medicine, energy and other fields being revolutionized by information technology. His graphs already show the beginning of exponential progress in nanotechnology, in the ease of gene sequencing, in the resolution of brain scans. With these new tools, he says, by the 2020s we’ll be adding computers to our brains and building machines as smart as ourselves.

This serene confidence is not shared by neuroscientists like Vilayanur S. Ramachandran, who discussed future brains with Dr. Kurzweil at the festival. It might be possible to create a thinking, empathetic machine, Dr. Ramachandran said, but it might prove too difficult to reverse-engineer the brain’s circuitry because it evolved so haphazardly.

“My colleague Francis Crick used to say that God is a hacker, not an engineer,” Dr. Ramachandran said. “You can do reverse engineering, but you can’t do reverse hacking.”

Dr. Kurzweil’s predictions come under intense scrutiny in the engineering magazine IEEE Spectrum, which devotes its current issue to the Singularity. Some of the experts writing in the issue endorse Dr. Kurzweil’s belief that conscious, intelligent beings can be created, but most think it will take more than a few decades.

He is accustomed to this sort of pessimism and readily acknowledges how complicated the brain is. But if experts in neurology and artificial intelligence (or solar energy or medicine) don’t buy his optimistic predictions, he says, that’s because exponential upward curves are so deceptively gradual at first.

“Scientists imagine they’ll keep working at the present pace,” he told me after his speech. “They make linear extrapolations from the past. When it took years to sequence the first 1 percent of the human genome, they worried they’d never finish, but they were right on schedule for an exponential curve. If you reach 1 percent and keep doubling your growth every year, you’ll hit 100 percent in just seven years.”

Dr. Kurzweil is so confident in these curves that he has made a $10,000 bet with Mitch Kapor, the creator of Lotus software. By 2029, Dr. Kurzweil wagers, a computer will pass the Turing Test by carrying on a conversation that is indistinguishable from a human’s.

I’m not as confident those graphs are going to hold up for fields besides computer science, so I’d be leery of betting on a date. But if I had to take sides in the 2029 wager, I’d put my money on Dr. Kurzweil. He could be right once again about a revolution coming sooner than expected. And I’d hate to bet against the chance to be around for this one.

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Hacking Earth Against Warming, Scientists Favor Fake Volcanoes

Could cannons, balloons and high-wire planes send sulfur back into the atmosphere and save the planet? As the Senate debates a controversial climate-change bill, meteorologists and economists alike say geoengineering solutions aren’t so far-out anymore.
The 1991 eruption of Mount Pinatubo in the Philippines sent 20 million tons of sulfur dioxide back into the stratosphere. Now scientists are wrestling over a potential delivery system for an artificial recreation of the natural effect—and over how much it would cost. (Photograph Courtesy of USGS/Cascades Volcano Observatory)

WASHINGTON — Faced with the potentially devastating consequences of climate change—including sea level rise and an ice-free Arctic—some scientists and policy experts have begun to consider an equally drastic countermeasure: geoengineering.
By physically altering the planet on a global scale, geoengineering projects would theoretically offset warming caused by the build-up of carbon dioxide in the atmosphere. The concept was dismissed as fringe science when it was first introduced in the 1960s. Now, what once seemed like science fiction is not only being deemed feasible, but necessary, said experts at a panel convened here Tuesday by the American Enterprise Institute for Public Policy Research, a conservative think tank.

One popular geoengineering scenario is to create an artificial volcano. Thomas Wigley, an expert on climate change based at the National Center for Atmospheric Research in Boulder, Colo., has created computer simulations that replicate the 1991 "Mount Pinatubo effect"—a temporary cooling period created by the launch of 20 million tons of sulfur dioxide into the stratosphere.

Wigley proposes mimicking the natural process by injecting sulfur dioxide or hydrogen sulfide into the same region, 60,000 to 70,000 ft. above the earth's surface. The compound would react to form a cloud of sulfuric acid droplets that would in turn reflect sunlight and cool the globe. Exactly how the material would be delivered isn't clear—cannons, balloons and high-flying military planes are some "highly speculative" options, he says.

Such a scheme isn't cheap. Depending on the frequency, delivery system and whom you talk to, estimates vary wildly from $1 billion to $50 billion a year. Whether it's worth the high price tag is still hotly debated.

Geoengineering would buy time for societies as they work on the technological revolution necessary to reduce carbon dioxide emissions, says Scott Barrett, an economist specializing in environment and international political economy at the School of Advanced International Studies at Johns Hopkins University in Baltimore.

"That's an excuse to conduct business as usual," says Alan Robock, a meteorologist at Rutgers University in New Brunswick, N.J. "It takes political will to lower carbon dioxide emissions. There are plenty of solutions already available."

Robock has also run the numbers on the artificial volcano scenario. Matching the Mount Pinatubo effect would involve launching 5 million tons of sulfur dioxide into the atmosphere every year for about four years. "That's going to be very expensive and locally polluting," he says.

Volcanic eruptions also destroy ozone. Geoengineering schemes that blast sulfur-containing compounds into the atmosphere could hinder the repair of the ozone hole by up to 70 years. The hole has been on the mend; it is estimated that it will disappear by the mid-21st century.

Both Robock's and Wigley's models suggest that this approach could reduce rainfall globally. Mount Pinatubo triggered lower rainfall, soil moisture and river flow in many regions. Volcanic eruptions at tropical latitudes cause warmer winters in the Northern Hemisphere, and eruptions at high latitudes can weaken the Asian and African monsoons.

There are other back-of-the-envelope geoengineering options for chilling the earth, including tinkering with cloud chemistry to make clouds more reflective. One such strategy involves droplet injection ships that essentially suck up seawater and shoot it into the clouds, altering the condensation nuclei. Another plan is to create artificial trees that extract carbon dioxide directly from the atmosphere.

Astronomer Roger Angel, of the University of Arizona, has proposed launching into orbit trillions of small lenses that would bend sunlight away from the planet. On the opposite end of the spectrum is the ultra-low-tech approach of painting rooftops white to reflect sunlight.

But even if geoengineering succeeds at turning down the world's temperature, it doesn't address other consequences of rising levels of greenhouse gases. As the oceans absorb carbon dioxide, for example, seawater will become more acidic—destroying coral reefs and marine creatures encased in calcium carbonate.

Jay Gulledge, an ecologist specializing in the carbon cycle at the Pew Center on Global Climate Change, points out that if geoengineering efforts produce negative effects "there's no guarantee that the climate will just switch back." The climate may shift permanently—as it seems to have done in the Sahel where rainfall has decreased, lakes have dried up and river levels have dropped, and in the North Pacific where changes in wind patterns have become more El Nino-like.

This week, the Senate is debating a climate change bill that would cap greenhouse gas emissions by two-thirds by 2050, and force polluters to buy permits to release carbon dioxide. Critics argue that promoting geoengineering now could undermine the need for such legislation.

In the future, they say, successful geoengineering projects could provide a false sense of security, and diminish the urgency of reducing greenhouse gas emissions. And should the fix unexpectedly fail, high CO2 levels from unabated emissions could trigger the worst-case scenario for global warming.

To be fair, no one on Tuesday's panel proposed geoengineering as a silver bullet, but something to be considered among a suite of steps that include reducing emissions and increasing R&D for carbon sequestration.

"Anyone who says that geoengineering offers a policy solution to climate change is decades ahead of the science," Gulledge says. "And that's not a safe place to be."

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