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Natural selection acts on the quantum world
Nature Magazine ^ | 23 December 2004 | Philip Ball

Posted on 12/23/2004 8:31:39 AM PST by PatrickHenry

Objective reality may owe its existence to a 'darwinian' process that advertises certain quantum states.

A team of US physicists has proved a theorem that explains how our objective, common reality emerges from the subtle and sensitive quantum world.

If, as quantum mechanics says, observing the world tends to change it, how is it that we can agree on anything at all? Why doesn't each person leave a slightly different version of the world for the next person to find?

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.

If it wasn't for quantum darwinism, the researchers suggest in Physical Review Letters [Ollivier H., Poulin D. & Zurek W. H. Phys. Rev. Lett., 93. 220401], the world would be very unpredictable: different people might see very different versions of it. Life itself would then be hard to conduct, because we would not be able to obtain reliable information about our surroundings... it would typically conflict with what others were experiencing.

Taking stock

The difficulty arises because directly finding out something about a quantum system by making a measurement inevitably disturbs it. "After a measurement," say Wojciech Zurek and his colleagues at Los Alamos National Laboratory in New Mexico, "the state will be what the observer finds out it is, but not, in general, what it was before."

Because, as Zurek says, "the Universe is quantum to the core," this property seems to undermine the notion of an objective reality. In this type of situation, every tourist who gazed at Buckingham Palace would change the arrangement of the building's windows, say, merely by the act of looking, so that subsequent tourists would see something slightly different.

Yet that clearly isn't what happens. This sensitivity to observation at the quantum level (which Albert Einstein famously compared to God constructing the quantum world by throwing dice to decide its state) seems to go away at the everyday, macroscopic level. "God plays dice on a quantum level quite willingly," says Zurek, "but, somehow, when the bets become macroscopic he is more reluctant to gamble." How does that happen?

Quantum mush

The Los Alamos team define a property of a system as 'objective', if that property is simultaneously evident to many observers who can find out about it without knowing exactly what they are looking for and without agreeing in advance how they'll look for it.

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.

"Decoherence selects out of the quantum 'mush' states that are stable, that can withstand the scrutiny of the environment without getting perturbed," says Zurek. These special states are called 'pointer states', and although they are still quantum states, they turn out to look like classical ones. For example, objects in pointer states seem to occupy a well-defined position, rather than being smeared out in space.

The traditional approach to decoherence, says Zurek, was based on the idea that the perturbation of a quantum system by the environment eliminates all but the stable pointer states, which an observer can then probe directly. But he and his colleagues point out that we typically find out about a system indirectly, that is, we look at the system's effect on some small part of its environment. For example, when we look at a tree, in effect we measure the effect of the leaves and branches on the visible sunlight that is bouncing off them.

But it was not obvious that this kind of indirect measurement would reveal the robust, decoherence-resistant pointer states. If it does not, the robustness of these states won't help you to construct an objective reality.

Now, Zurek and colleagues have proved a mathematical theorem that shows the pointer states do actually coincide with the states probed by indirect measurements of a system's environment. "The environment is modified so that it contains an imprint of the pointer state," he says.

All together now

Yet this process alone, which the researchers call 'environment-induced superselection' or einselection [Zurek W. H. Arxiv, Preprint, link at footnote 2 in original article], isn't enough to guarantee an objective reality. It is not sufficient for a pointer state merely to make its imprint on the environment: there must be many such imprints, so that many different observers can see the same thing.

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.

This multiplicity of imprints of the pointer states happens precisely because those states are robust: making one imprint does not preclude making another. This is a Darwin-like selection process. "One might say that pointer states are most 'fit'," says Zurek. "They survive monitoring by the environment to leave 'descendants' that inherit their properties."

"Our work shows that the environment is not just finding out the state of the system and keeping it to itself", he adds. "Rather, it is advertising it throughout the environment, so that many observers can find it out simultaneously and independently."


TOPICS: Miscellaneous; Philosophy
KEYWORDS: physics; quantummechanics
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I donno about this one. But it's a slow day for new threads.
1 posted on 12/23/2004 8:31:39 AM PST by PatrickHenry
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To: VadeRetro; Junior; longshadow; RadioAstronomer; Doctor Stochastic; js1138; Shryke; RightWhale; ...
Science Ping! This is an elite subset of the Evolution ping list.
See the list's description in my freeper homepage. Then FReepmail me to be added or dropped.

2 posted on 12/23/2004 8:32:32 AM PST by PatrickHenry (The List-O-Links for evolution threads is at my freeper homepage.)
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To: PatrickHenry
Whoa, I have not had nearly enough coffee for this...
3 posted on 12/23/2004 8:35:12 AM PST by general_re ("What's plausible to you is unimportant." - D'man)
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To: TexasGreg

Ping


4 posted on 12/23/2004 8:37:33 AM PST by GarySpFc (Sneakypete, De Oppresso Liber)
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To: PatrickHenry
If, as quantum mechanics says, observing the world tends to change it, how is it that we can agree on anything at all?

Gibberish. On three levels.

5 posted on 12/23/2004 8:41:04 AM PST by RightWhale (Destroy the dark; restore the light)
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To: RightWhale

Ok, if its gibberish, can you demonstrate a time event that is NOT a kinetic energy event?


6 posted on 12/23/2004 8:50:18 AM PST by timer
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To: PatrickHenry
This seems an interesting parallel to the theories put forward by Julian Barbour in The End of Time

Neat stuff...

7 posted on 12/23/2004 8:53:03 AM PST by Lloyd227 (American Forces armed with what? Spit balls?)
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To: PatrickHenry

Evolution (of all things) is evidence of God's existence. St Thomas Acquinas


8 posted on 12/23/2004 8:53:32 AM PST by HamiltonJay
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To: timer
demonstrate a time event that is NOT a kinetic energy event?

The power available through kinetic energy is vastly underrated. Time, however, is a percept.

9 posted on 12/23/2004 8:55:38 AM PST by RightWhale (Destroy the dark; restore the light)
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To: PatrickHenry

"I donno about this one. But it's a slow day for new threads."

L O L!


10 posted on 12/23/2004 8:57:28 AM PST by Just mythoughts
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To: PatrickHenry
quantum darwinism

Oh L-rd.

Here come the Quantum Creationists.

11 posted on 12/23/2004 8:58:34 AM PST by Lazamataz ("Stay well - Stay safe - Stay armed - Yorktown" -- harpseal)
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To: PatrickHenry

Well, this is interesting. Darwinism continues to show general utility. How would Creationism possibly be used here?


12 posted on 12/23/2004 9:02:13 AM PST by orionblamblam
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To: PatrickHenry
"the Universe is quantum to the core,"

I always said it was turtles all the way down.

13 posted on 12/23/2004 9:03:07 AM PST by js1138 (D*mn, I Missed!)
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Comment #14 Removed by Moderator

To: general_re

Amen!


15 posted on 12/23/2004 9:08:49 AM PST by Junior (FABRICATI DIEM, PVNC)
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To: PatrickHenry

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.


16 posted on 12/23/2004 9:27:25 AM PST by doc30 (Democrats are to morals what and Etch-A-Sketch is to Art.)
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To: PatrickHenry
As a companion to this, I'd recommend An Elegant Universe.
17 posted on 12/23/2004 9:29:14 AM PST by optimistically_conservative (The soldier, be he friend or foe, is charged with the protection of the weak and the unarmed.)
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To: PatrickHenry
Is anyone aware of a PHYSICS ping list here on FR?

Quantum Physics has been a fascination of mine for some time now. I'd rather NOT get pinged to a creationist / evolutionist list.

Thanks
18 posted on 12/23/2004 9:43:50 AM PST by taxed2death (A few billion here, a few trillion there...we're all friends right?)
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To: PatrickHenry
Is anyone aware of a PHYSICS ping list here on FR?

Quantum Physics has been a fascination of mine for some time now. I'd rather NOT get pinged to a creationist / evolutionist list.

Thanks
19 posted on 12/23/2004 9:44:35 AM PST by taxed2death (A few billion here, a few trillion there...we're all friends right?)
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To: PatrickHenry
Nice article.

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.

20 posted on 12/23/2004 10:27:15 AM PST by snarks_when_bored
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To: PatrickHenry
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

21 posted on 12/23/2004 10:33:03 AM PST by snarks_when_bored
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To: orionblamblam

Ladder operators, perhaps. :-)


22 posted on 12/23/2004 10:37:19 AM PST by grey_whiskers (The opinions are solely those of the author and are subject to change without notice.)
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To: doc30
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!

23 posted on 12/23/2004 10:40:36 AM PST by grey_whiskers (The opinions are solely those of the author and are subject to change without notice.)
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To: grey_whiskers

Merry Christmas, too!


24 posted on 12/23/2004 10:49:47 AM PST by doc30 (Democrats are to morals what and Etch-A-Sketch is to Art.)
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To: Lazamataz

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

25 posted on 12/23/2004 11:30:02 AM PST by general_re ("What's plausible to you is unimportant." - D'man)
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To: PatrickHenry
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).

26 posted on 12/23/2004 12:00:58 PM PST by Physicist
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To: snarks_when_bored; PatrickHenry
I Blog Books...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.
27 posted on 12/23/2004 12:04:42 PM PST by dr_pat (the boys i mean are not refined, they shake the mountains when they dance!)
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To: dr_pat
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!

28 posted on 12/23/2004 12:25:56 PM PST by snarks_when_bored
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To: Physicist
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.

29 posted on 12/23/2004 12:31:22 PM PST by PatrickHenry (The List-O-Links for evolution threads is at my freeper homepage.)
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To: PatrickHenry
>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 . . .

30 posted on 12/23/2004 12:34:55 PM PST by theFIRMbss
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To: Physicist

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.


31 posted on 12/23/2004 12:43:18 PM PST by snarks_when_bored
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To: PatrickHenry

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


32 posted on 12/23/2004 1:12:27 PM PST by Condorman (Changes aren't permanent, but change is.)
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To: snarks_when_bored; Physicist
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!
33 posted on 12/23/2004 1:18:37 PM PST by PatrickHenry (The List-O-Links for evolution threads is at my freeper homepage.)
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To: theFIRMbss

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.)


34 posted on 12/23/2004 1:50:06 PM PST by Doctor Stochastic (Vegetabilisch = chaotisch is der Charakter der Modernen. - Friedrich Schlegel)
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To: Physicist
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!
35 posted on 12/23/2004 2:23:09 PM PST by grey_whiskers (The opinions are solely those of the author and are subject to change without notice.)
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To: PatrickHenry
"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...

36 posted on 12/23/2004 2:25:40 PM PST by grey_whiskers (The opinions are solely those of the author and are subject to change without notice.)
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To: Doctor Stochastic
>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 . . .

37 posted on 12/23/2004 2:28:47 PM PST by theFIRMbss
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To: snarks_when_bored
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. :-)

38 posted on 12/23/2004 2:46:59 PM PST by jennyp (Latest creation/evolution news: http://crevo.bestmessageboard.com)
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To: PatrickHenry

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

Just wondering.


39 posted on 12/23/2004 2:54:17 PM PST by wotan
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To: 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.
40 posted on 12/23/2004 3:10:37 PM PST by wotan
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To: wotan

I donno. I just post the stuff. Maybe one of the smart guys around here can help.


41 posted on 12/23/2004 3:28:13 PM PST by PatrickHenry (The List-O-Links for evolution threads is at my freeper homepage.)
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To: RightWhale
By percept I assume you mean perception. Kinetic energy IS time, the rate thereof, or dKE. There is no such thing as "time" in and of itself, thus no such thing as "space-time"; thus 5 dimensional xyzwp. What DOES exist is wave energy and particle energy, the 2 great languages of complementarity. When wave gets out of balance with particle(WsPv)you get TIME, a quantum movie that gives one living in the CM world the ILLUSION of continuous motion/time-as-a-river of nows. When Ws=Pv you get the balance that you call Momentum. Thus, t=dKE=m=(Ws not=to Pv) and not-t=PE=M=(Ws=Pv). Time-mass is IMBALANCE, not-time is Momentum is BALANCE. So, Heisenberg and Einstein both made oxymoron boo-boos : delta momentum and rest mass...think about what they actually say....
42 posted on 12/23/2004 5:12:35 PM PST by timer
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To: orionblamblam

This is quantum natural selection, not quantum evolution. As someone who questions macro-evolution, I have no problem with the ideas put forth in this article.


43 posted on 12/23/2004 5:18:42 PM PST by puroresu
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To: longshadow
TimeCube placemarker.
44 posted on 12/23/2004 5:23:22 PM PST by PatrickHenry (The List-O-Links for evolution threads is at my freeper homepage.)
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To: Dataman

Metaphysical paraconformities ping. (aka quantum fun-house mirror)


45 posted on 12/23/2004 5:24:13 PM PST by Thinkin' Gal
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To: PatrickHenry
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.

My understanding is different. Decoherence is interaction with the environment destroying entanglement - in effect, the environment "factors" an entangled quantum state into independent parts. It does not explain how a mixed state "collapses" to a single outcome.

46 posted on 12/23/2004 5:37:17 PM PST by edsheppa
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To: PatrickHenry

Whoever wrote this apparently has been spending too much time with my sister or has fallen into a Mixmaster at some point in his life.


47 posted on 12/23/2004 5:56:36 PM PST by Old Professer (When the fear of dying no longer obtains no act is unimaginable.)
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To: edsheppa

This whole mess is B.S.; rather like comparing a telescope to a fishing net.


48 posted on 12/23/2004 5:58:09 PM PST by Old Professer (When the fear of dying no longer obtains no act is unimaginable.)
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To: PatrickHenry

YEC INTREP


49 posted on 12/23/2004 6:01:56 PM PST by LiteKeeper (Secularization of America is happening)
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To: Doctor Stochastic
>or at least they own a floating crap game, on a riverboat.<

... or in the back of the Biltmore Garage, especially if his name is Nathan.

50 posted on 12/23/2004 6:14:07 PM PST by longshadow
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