Physicists have 'solved' mystery of levitation
By Roger Highfield, Science Editor
In theory the discovery could be used to levitate a person
Levitation has been elevated from being pure science fiction to science fact, according to a study reported today by physicists.
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.
Thursday, June 5, 2008
Why some prayers are unanswered!
http://www.theonion.com/content/news_briefs/report_32_of_prayers
Report: 32% Of Prayers Deflected Off Passing Satellites
HOUSTON—According to an official NASA report released Saturday, nearly 32 percent of all prayers exiting Earth are deflected off satellites orbiting the planet—ultimately preventing the discharged requests for divine intervention from ever making it to the Gates of Heaven. "After impact with the satellite, these diverted prayers typically plummet back into the atmosphere, where they either burn up or eventually land, unanswered, in a body of water," the report read in part. "Of the remaining prayers, research confirms 64 percent fail to make it past the stratosphere because they aren't prayed hard enough, 94 percent of those with enough momentum are swallowed by a supermassive black hole at the center of the Milky Way galaxy, and 43 percent are eaten by birds." The report concluded that, of the 170 billion prayers issued last month, one made it to God, whose reply was intercepted by a hurricane and incorrectly delivered to a Nigerian man who reportedly did not know what to do with his brand-new Bowflex machine.
Gamma Ray Delay May Be Sign of 'New Physics'
Delayed gamma rays from deep space may provide the first evidence for physics beyond current theories.
The MAGIC (Major Atmospheric Gamma-ray Imaging Cherenkov) telescope found that high-energy photons of gamma radiation from a distant galaxy arrived at Earth four minutes after lower-energy photons, although they were apparently emitted at the same time. If correct, that would contradict Einstein's theory of relativity, which says that all photons (particles of light) must move at the speed of light.
"Everybody's very excited," about this result, said Daniel Ferenc, a physics professor at UC Davis and a member of the MAGIC collaboration. Ferenc cautioned that the results need to be repeated with other gamma-ray sources and that a simpler explanation had not been ruled out. But, "it shows that such measurements are possible," he said.
The researchers propose that the delay could be caused by photons interacting with "quantum foam," a type of structure of space itself. Quantum foam is predicted by quantum gravity theory, an attempt to unite quantum physics and relativity at cosmic scales.
The astronomers pointed the telescope at Markarian 501, a galaxy half a billion light-years away that contains a "blazar" -- a massive black hole that gives off bursts of gamma rays. Some of the material falling toward the black hole gets squeezed into jets that burst from the poles of the object at close to the speed of light. These jets fire off flares of gamma rays a few minutes long.
The researchers sorted high- and low-energy gamma-ray photons coming from the object with each flare. Joined by a group of theoretical physicists led by John Ellis from CERN, the MAGIC team showed that the high- and low-energy photons appeared to have been emitted at the same time. But the high-energy photons arrived four minutes late after traveling through space for about 500 million years.
The work has been submitted for publication in Physics Review Letters.
Additional information:
Media contact(s):
- Daniel Ferenc, Physics, (530) 752-0917, ferenc@physics.ucdavis.edu
- Andy Fell, UC Davis News Service, (530) 752-4533, ahfell@ucdavis.edu
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