Sunday, January 18, 2009
Friday, January 16, 2009
Resolving A Quantum Paradox with The Atomic Knights
"For nearly a century, the widespread interpretation of quantum mechanics suggests that everything is uncertain until it is observed, and that observation inevitably alters reality," says Professor Steinberg. "However, in the 1990s, a technique known as 'interaction-free measurement' seemed to promise the ability to 'see without looking’. But when Lucien Hardy proposed that one could never reliably make inferences about past events which hadn't been directly observed, a paradox emerged which suggested that whenever one attempted to reason about the past in this way they would be led into error.
Scientists have now combined Hardy's Paradox with a new theory known as weak measurement showing that in one sense, one can indeed talk about the past, resolving the paradox. Weak measurement is a tool whereby the presence of a detector is less than the level of uncertainty around what is being measured, so that there is an imperceptible impact on the experiment.
"We found that all of the seemingly paradoxical conclusions in Hardy's Paradox can, in fact, be experimentally verified," says Steinberg, "but that the use of weak measurement removes the contradiction."
"Until recently, it seemed impossible to carry out Hardy's proposal in practice, let alone to confirm or resolve the paradox," he says. "We have finally been able to do so, and to apply Aharonov's methods to the problem, showing that there is a way, even in quantum mechanics, in which one can quite consistently discuss past events even after they are over and done. Weak measurement finds what is there without disturbing it." link
Strange Adventures #141 (June, 1962). Atomic Knights © DC Comics
Click To Enlarge
Scientists have now combined Hardy's Paradox with a new theory known as weak measurement showing that in one sense, one can indeed talk about the past, resolving the paradox. Weak measurement is a tool whereby the presence of a detector is less than the level of uncertainty around what is being measured, so that there is an imperceptible impact on the experiment.
"We found that all of the seemingly paradoxical conclusions in Hardy's Paradox can, in fact, be experimentally verified," says Steinberg, "but that the use of weak measurement removes the contradiction."
"Until recently, it seemed impossible to carry out Hardy's proposal in practice, let alone to confirm or resolve the paradox," he says. "We have finally been able to do so, and to apply Aharonov's methods to the problem, showing that there is a way, even in quantum mechanics, in which one can quite consistently discuss past events even after they are over and done. Weak measurement finds what is there without disturbing it." link
Ref: Experimental Joint Weak Measurement on a Photon Pair as a Probe of Hardy's Paradox. 2009. J. S. Lundeen and A. M. Steinberg. Phys. Rev. Lett. 102, 020404 (2009)
Strange Adventures #141 (June, 1962). Atomic Knights © DC Comics
Click To Enlarge
Thursday, January 15, 2009
Worn This Day (1797): First Top Hat
Art by Art Adams
In 1797, the top hat was first worn in England by James Heatherington, a Strand haberdasher in London. An issue of the Times of that period records that when he left his shop with his extraordinary headwear, a crowd of onlookers assembled, which degenerated into a shoving match. Heatherington was summoned to appear in court before the Lord Mayor and fined £50 for going about in a manner "calculated to frighten timid people."Within a month, he was overwhelmed with orders for the new top hats. link
Zatanna © DC Comics
Monday, January 12, 2009
Saturday, January 10, 2009
Solved: The Mystery of The Walking Martian Rocks
Rocks on Mars are on the move, rolling into the wind and forming organized patterns, according to new research.
The new finding counters the previous explanation of the evenly spaced arrangement of small rocks on Mars. That explanation suggested the rocks were picked up and carried downwind by extreme high-speed winds thought to occur on Mars in the past.
Pelletier and his colleagues suggest that wind blows sand away from the front of the rock, creating a pit, and then deposits that sand behind the rock, creating a hill. The rock then rolls forward into the pit, moving into the wind, he said. As long as the wind continues to blow, the process is repeated and the rocks move forward.
These Spirit Rover camera images of the intercrater plain between Mars' Lahontan Crater show uniformly-spaced small rocks, known as clasts. Credit: GSA
Pelletier plans to apply the same models to larger features on Mars such as sand dunes and wind-sculpted valleys and ridges called "yardangs." press release
Ref.: Wind-Driven Reorganization of Coarse Clasts on the Surface of Mars. 2008. Geology
NASA Mars Exploration Rover Mission
NASA Mars Exploration Rover Mission
Saturday, January 3, 2009
Thursday, January 1, 2009
Announced This Day: Discovery of X-Rays
In 1896, German scientist, Wilhelm Röntgen announced his discovery of x-rays. He sent copies of his manuscript and some of his x-ray photographs to several renowned physicists and friends, including Lord Kelvin in Glasgow and Henre Poincare in Paris. Four days later, on 5 Jan 1896, Die Presse published the news in a front-page article which described the discovery and suggested new methods of medical diagnoses might be made with this new kind of radiation. link
'X'-The Man With X-Ray Eyes
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