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[sighs] These kind of threads always make me wonder why if the researchers have a deep insight into randomness, they don't live in Las Vegas . . . |
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Gibberish. On three levels.
Neat stuff...
Evolution (of all things) is evidence of God's existence. St Thomas Acquinas
"I donno about this one. But it's a slow day for new threads."
L O L!
Oh L-rd.
Here come the Quantum Creationists.
Well, this is interesting. Darwinism continues to show general utility. How would Creationism possibly be used here?
I always said it was turtles all the way down.
Sounds like a joke thread to me. All life is macroscopic in nature - even viruses and bacteria. No living thing exists on the Plank scale. An observation, in the sense of quantum mechanics occurs on the size scale were quantum mechanics dominates. To influence a quantum state, you must observe on the quantum scale. At our large scale, quantum effects blurr into the classical laws of physics. This is the decoherence mentioned in the article.
This is the part of the articel I have trouble with: Physicists agree that the macroscopic or classical world (which seems to have a single, 'objective' state) emerges from the quantum world of many possible states through a phenomenon called decoherence, according to which interactions between the quantum states of the system of interest and its environment serve to 'collapse' those states into a single outcome. But this process of decoherence still isn't fully understood.
I always thought that the quantum states were properties associated with materials invovled. For example, the green in the leaves of a tree arise from the absorption of light of a frequency whose energy matches the quantum transition from a ground state to an excited state in chlorophyll. One molecule of chlorophyll is like every other and has the same transition state. The only change would be slight variations in its chemical environent that can casue the energy for the transition to shift slightly higher or lower, hence casuing a broadening of the wavelength window responsible for the observed color. I don't see where the authors see a continuum of states and some are selected on a macroscopic scale when the quantum effects are entirely macroscopic and the possible states are determined before even reaching the classical domain.
It is physically impossible even for two macroscopic observers to see the exact same thing. For example, if two people were looking at a flower, each person sees something different. Different photons of light reach the different people. No two people detect the same photon or the same transition.
The environment as a whole is always declaring itself to itself (more or less clearly and distinctly, as Descartes might have put it), and the states of the environment which are able to successfully (and consistently) declare themselves to their surroundings are the states which come to be regarded as objective by observers (should there be any).
From one part to all of the others: makes sense to me.
Decoherence is caused by the interaction with the environment. Environment monitors certain observables of the system, destroying interference between the pointer states corresponding to their eigenvalues. This leads to environment-induced superselection or einselection, a quantum process associated with selective loss of information. Einselected pointer states are stable. They can retain correlations with the rest of the Universe in spite of the environment. Einselection enforces classicality by imposing an effective ban on the vast majority of the Hilbert space, eliminating especially the flagrantly non-local "Schrödinger cat" states. Classical structure of phase space emerges from the quantum Hilbert space in the appropriate macroscopic limit: Combination of einselection with dynamics leads to the idealizations of a point and of a classical trajectory. In measurements, einselection replaces quantum entanglement between the apparatus and the measured system with the classical correlation.
And here's a link to the PDF version of Zurek's pre-print article:
Decoherence, einselection, and the quantum origins of the classical
Happily, this tends to happen automatically, because each individual's observation is based on only a tiny part of the environmental imprint. For example, we're never in danger of 'using up' all the photons bouncing off a tree, no matter how many people we assemble to look at it.
If you assemble enough people, those in the back won't be able to see the tree, because others are in the way. The people in front used up those photons, you see (or not, as the case may be).
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[sighs] These kind of threads always make me wonder why if the researchers have a deep insight into randomness, they don't live in Las Vegas . . . |
I read it. It hurt. I'm going to go lie down for a while.
What's the superiority of Zurek's approach over Bohmian mechanics?
Just wondering.
Metaphysical paraconformities ping. (aka quantum fun-house mirror)