Natural selection acts on the quantum world

Nature Magazine ^ | 23 December 2004 | Philip Ball

[snarks_when_bored]

Here's Zurek's abstract for his pre-print article:

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

[grey_whiskers]

Ladder operators, perhaps. :-)

[grey_whiskers]

No two people detect the same photon or the same transition.

All right, I'll bite, I don't mind.

What about when the light is acting like a wave?
Rayleigh, Jeans
had not the means
Einstein didn't want 'em
It took Neils Bohr
and several more
to figure out the quantum...

(Hazy quote from memory, from (I believe) an old article in Physics Today...)

Cheers and Merry Christmas!

[doc30]

Merry Christmas, too!

[general_re]

"Actually, I'm a Quantum Presbyterian..."

[Physicist]

Frankly, none of this sounds Darwinian at all. I suppose they just thought "quantum Darwinism" sounded catchy.

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).

[dr_pat]

...einselection, a quantum process associated with selective loss of information.

Where the Darwinian (macroscopic) process retains information, expressing or surpressing as required to meet selection conditions, the quantum process results in loss of information? I know, I know, it's a super-simplification for both concepts.

But if "observation" on the quantum level is required for decoherence, of what does that observation consist? At our level, the macroscopic and microscopic, we see, weigh and measure. What/who is the observer which sees the unselected quantum observeables, selecting some and finding others "weighed in the balance and found wanting"?

And are the non-einselected states truly lost, or merely unexpressed?

As for the Quantum Creationists, "God retreats faster than we can find Him in our telescopes." And microscopes as well.

[snarks_when_bored]

I'm not qualified to pronounce on Zurek's ideas, so let me do so.

Zurek speaks of 'environmental monitoring', seeming to reserve 'observing' for the sort of monitoring that we do. What might monitoring mean if there are no observers like us around? Something along these lines, I'd surmise: exchanges of energy/momentum. A source of photons, for example, is announcing itself to its surroundings, and any absorption event of any of the emitted photons constitutes a 'monitoring' of the emitter by the absorber. If the source is constant and prolific, there will be many opportunities for many different absorbers to 'monitor' that source. It's precisely such sources that observers (whenever and wherever they come to be) come to recognize as 'objective'.

If I can find some time, I'm going to read selected portions of Zurek's pre-print (skipping over the parts that would require too much work to understand). If I find reason to modify the previous paragraph, I'll post a correction on this thread. However, if I don't post a correction, don't take that as evidence that the previous paragraph is correct. Maybe I just didn't get around to reading the pre-print, or, if I did, I didn't properly understand it!

[PatrickHenry]

Frankly, none of this sounds Darwinian at all. I suppose they just thought "quantum Darwinism" sounded catchy.

Yup. "Charm"ing.

If you assemble enough people, those in the back won't be able to see the tree ...

And if everyone goes home, the decoherence goes with them, the forest reverts to quantum mush, and the elves come out to play.

[theFIRMbss]

>Because, say the researchers, certain special states of a system are promoted above others by a quantum form of natural selection, which they call quantum darwinism. Information about these states proliferates and gets imprinted on the environment. So observers coming along and looking at the environment in order to get a picture of the world tend to see the same 'preferred' states.

[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 . . .

[snarks_when_bored]

The 'pointer states' are the 'robust' states, which are able to survive and continue to announce themselves to their surroundings. The analogy with Darwinism is a bit strained, I'll agree. Zurek wouldn't be the first physicist to co-opt some aspect of evolution into physics. Lee Smolin comes to mind.

[Condorman]

I read it. It hurt. I'm going to go lie down for a while.

[PatrickHenry]

Presumably, upon decoherence, there must be an exchange of particles to announce the "pointer states" to an otherwise disorganized universe. From my long-ago military days, I suggest the term guide-ons. Everything that pops into reality sends out a growing ripple of guide-ons, and everything that exists lives in a "guide-on field." Gee, this is fun!

[Doctor Stochastic]

Those with a deep understanding of randomness either avoid Las Vegas (and other gambling estblishments) or the own one (or at least they own a floating crap game, on a riverboat.)

[grey_whiskers]

I betcha this was 'sloppy writing' and the earlier quote meant "don't use up just by seeing." Of course lotsa photons get abosorbed by skin, clothes, hair, or bounced away. Cheers! ...oh, and Merry Christmas!

[grey_whiskers]

"I suggest the term guide-ons."

I dunno. When I was a teenager, and just learning about quantum, I misread the term "hadron" as "hardon."
I was giggling for days until I realized my mistake.

Ah, the wonders of selective dyslexia...

[theFIRMbss]

>Those with a deep understanding of randomness either avoid Las Vegas ...

Color me poor, but
I bet some day, someone with
stochastic rachets

("Parrondo games") makes
roulette a "game" of the past.
Now, lottery games . . .

[jennyp]

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...

Thank you, modern science, for providing yet more evidence of the truth of creationism! All you scientist scaled the mountaintops only to find the priests already there. Here's how it works...

This loss of information happened at The Fall. When G-D kicked Adam & Eve out of the garden, He removed H~s protection of all the majickal, non-localized quantum states, eventually leaving only cold, cruel, Darwinian objectivity to survive.

In short: Objectivity is all Satan's fault.

But now, if we let G*D into our hearts, He'll extend H-s protection back to all those fragile quantum states while you pray to H^m. This is why prayer produces miracles.

(This argument, or something like it, coming soon to an AiG or Creation/Evolution Headlines website near you. :-)

[wotan]

What's the superiority of Zurek's approach over Bohmian mechanics?

Just wondering.

[wotan]

Checking out the concluding remarks section of Zurek's paper, I see:

Ideas based on the immersion of the system in the environment have recently gained enough support to be described (by sceptics!) as “the new orthodoxy” (Bub, 1997). This is a dangerous characterization, as it suggests that the interpretation based on the recognition of the role of the environment is both complete and widely accepted. Neither is certainly the case.

In other words, Zurek's approach is not known to work, whereas Bohmian mechanics is known to be equivalent to the Copenhagen interpretation where the latter is unambiguous.