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Mecânica Quântica, mindfucking us desde 1920

10.07.10

 

"In the latest attempt, researchers at the University of Geneva in Switzerland tried to determine whether entanglement—the fact that measuring a property of one particle instantly determines the property of another—is actually transmitted by some wave-like signal that's fast but not infinitely fast.

 

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The photons were indeed entangled, the group reports in Nature. But in reality, no experiment is perfect, so what they end up with is a lower limit on how fast the entanglement could be traveling: 10,000 times the speed of light.

To appreciate the weirdness of entanglement, consider that the outcome of a single quantum measurement is random. By all tests, a photon *has* no definite polarization until it hits a detector capable of measuring it. So it's like the entangled particles share one big quantum state."

 

Este bocadinho de bad crazyness, tirado daqui.

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uau...

10.07.10

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A Palavra Viva

10.07.10

 

"The 7th Forum of European Neuroscience, held in Amsterdam this week, heard that learning to read requires the brain’s visual system to undergo profound changes, including unlearning the ancient ability to recognise an object and its mirror image as identical.

 

Stanislas Dehaene, a cognitive neuroscientist at the French medical-research agency, INSERM, believes that skills acquired relatively recently in people’s evolutionary past must have piggybacked on regions in the brain that originally evolved for other purposes, since there has not been time for dedicated neural systems to develop from scratch.

 

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His studies suggest that one small area of the brain’s visual system is particularly activated by the written word. Dr Dehaene calls this the visual word form area (VWFA). Researchers debate the extent to which this area is specialised for word recognition, since it also responds to pictures. But Dr Dehaene thinks the VWFA evolved for object recognition and is requisitioned for word recognition. Unfortunately, it has one property that, though valuable when recognising objects, is not helpful for reading: more than other parts of the visual system it is activated both by an object and by that object’s mirror image.

 

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Some writing systems, like the ancient Greeks’ boustrophedon, in which alternate lines are read in opposite directions, appear to actually support these pre-literay inclinations. In fact, so do most alphabets. Other researchers have shown that the brain region that corresponds to the VWFA in monkeys is particularly sensitive to certain shapes, such as Y, T and L. The line junctions in these letters, when found in nature, provide valuable spatial information, such as whether an object is in front of or behind another. Dr Dehaene thinks that our visual system became sensitised to them early on, and that letters were later selected because they exploited the sensitivities of the human brain to such shapes. That is why such shapes are common to all alphabets, he says.

 

In his latest work, Dr Dehaene has shown that literacy may change the brain in other ways too. With a group of colleagues, he compared the brain responses of illiterate and literate adults to words and other visual stimuli, including faces. They found that the patterns of activity elicited by faces, in particular, were different in literate and illiterate brains."

 

Tirado daqui.

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