Thursday, September 30, 2004

Quanta on my mind

Is the universe friendly? (By Geoff Olson, Common Ground)

    experimentA fundamental experiment in quantum physics involves shining a beam of light at a barrier with two open slits. Some of the light gets through the barrier, forming an interference pattern on a screen. This indicates light has the property of a wave. Yet if you close one slit, leaving the other open, the light appears as just a single shaft of light built up photon by photon on the screen, which indicates that light has a particle property.

    Forget for a moment that no one has ever truly figured out how light can be both a particle and a wave at the same time, things which are as different as baseballs and Bach fugues. The critical part is that how it behaves depends upon the experimental setup. Ask nature a question a certain way, and you get a certain answer. (According to quantum physicist Werner Heisenberg, “What we observe is not nature itself, but nature exposed to our method of questioning.”)

    ... In other words, the nature of the question determines the reality you perceive. Our choice plays a critical role in determining the outcome of a situation in our local space-time - at least for experiments with photons.

    If our choices have this kind of dynamic going with the quantum world, the question then becomes how deep does this craziness run? Scientists insist such paradoxical phenomena are limited to the nano-world of the quantum. At larger scales, they are smudged out by the cancellation of a huge number of differing quantum states. It’s called “decoherence,” and it prevents the Alice in Wonderland weirdness of quantum physics from erupting into the kitchen, boardroom, or lab.

    Yet with the discovery of “microtubules” in human neurons, there is some evidence that the human brain may actually process some information on a quantum level, which may or may not reopen this whole can of worms for the macro level of reality. More here

NanoBot Backgrounder
Nuclear spintronics: quantum Hall and nano-systems
Nano on the brain

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