Water has emergent properties?

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  • #1
Diderot
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What do physicists think about water as an example of something with emergent properties?
Wiki: “The first emergentist theorists used the example of water having a new property when hydrogen, H, and oxygen, O, combine to form H2O (water). In this example there emerge such new properties as liquidity under standard conditions.”
I wonder if the concept of emergent properties has become main stream in modern physics. If so, what happened to reductionism?
Wiki: “Put in abstract terms the emergent theory asserts that there are certain wholes, composed (say) of constituents A, B, and C in a relation R to each other; that all wholes composed of constituents of the same kind as A, B, and C in relations of the same kind as R have certain characteristic properties; that A, B, and C are capable of occurring in other kinds of complex where the relation is not of the same kind as R; and that the characteristic properties of the whole R(A, B, C) cannot, even in theory, be deduced from the most complete knowledge of the properties of A, B, and C in isolation or in other wholes which are not of the form R(A, B, C).”
Does this go for water?
 

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  • #2
Pythagorean
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I don't see emergence and reductionism as being mutually exclusive. The emergent properties of water won't occur with one water molecule (or even a couple, really). But we can still explain the emergent properties in reductionist terms (coupling effects between the members of the ensemble). I don't know of any way of predicting all the properties of unknown molecules made by combining known atoms. Certainly we can make educated guesses, but material scientists use a lot of trial and error in the end.

In modeling nature, there exists mathematical systems that are sensitive to initial conditions and aren't analytically solvable (thus requiring computers to solve numerically) and are fundamentally unpredictable despite being deterministic. Coupling several such elements together leads to new behaviors that there is no way (that I know of) of predicting.
 
  • #3
arildno
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No emergent property can arise that are not in accordance with the laws of interaction governing the "small".

For example, independent measurability of momentum and position of a "particle" is a statistical assemblage effect that can be regarded as an emergent property of matter.
 
  • #4
Diderot
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Pythagorean and Arildno, thank you for your response. Do you use terms like 'emergence' and 'emergent property' in rigidly accurate sense as described in the wiki quote in the OP?

Pythagorean you state that you don't see emergence and reductionism as being mutually exclusive, but the wiki definition of emergence, as I understand it, excludes deduction from the parts.

Arildno, you state that no emergent property can arise that is not in accordance with the laws of interaction, but do you mean that these emergent properties are nevertheless not deducible from these laws?

To be clear, do you believe in so called emergent properties of water, that are in principle not deducible from the most complete knowledge of a lower level?
 
  • #5
arildno
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Hmm..I wrote "in accordance with", didn't I?

That's something quite different from "deducible".

Or what do you think?
 
  • #6
Diderot
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Arildno,
No emergent property can arise that are not in accordance with the laws of interaction governing the "small".
Do you mean by 'in accordance with the laws of interaction governing the "small"' : 'within the broad boundaries of the laws of interaction, which are leaving a huge bandwidth for the 'not-so-small' to 'create ex nihilo' irreducible properties?
Or are these laws strict and causing clear predictable effects, so there is no emergent property in the sense of not being deducible in principle from the most complete knowledge of a lower level?
 
  • #7
ZapperZ
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What do physicists think about water as an example of something with emergent properties?
I wonder if the concept of emergent properties has become main stream in modern physics. If so, what happened to reductionism?

Boy, you must have missed Phil Anderson's "More Is Different" essay, and all those papers by Bob Laughlin!

You may also want to read this:

https://www.physicsforums.com/showpost.php?p=2207270&postcount=81

Zz.
 
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  • #8
arildno
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"within the broad boundaries of the laws of interaction, which are leaving a huge bandwidth for emergent properties to come up (ex nihilo with something irreducible?)"

That is PRECISELY what I mean.

I don't understand what I've placed within a parenthesis; I must say that I cannot regard "deducibility" as a precise enough concept to be of any use. What is deducible for one person isn't deducible for another. And, we do not have any sort of solid knowledge to properly define "maximal deducibility" for humans in general.

For example:
Suppose the laws of the "small" allows a RANGE of behaviour for all matter to act according to.
The behaviour of "The large" must necessarily be in accordance with that specified range, even though, obviously, the actual range of behaviour for "The Large" will show surprising statistical deviancies in what is "common behaviour" on that level, relative to what is "common behaviour" on the scale of "The Small". Such surprising statistical deviancies, for example that for "The Large", it is meaningful and possible, to measure position and momentum of a "particle" independently (and accurately) of each other, is one such "emergent" property.
In my view, that is.

(Note that Heisenberg's famed uncertainty relation is, in principle, as valid for "The Small" as it is for "The Large"; in the latter case, it shows that certainty is, indeed, a feature of the macroworld)
 
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  • #9
Pythagorean
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Pythagorean you state that you don't see emergence and reductionism as being mutually exclusive, but the wiki definition of emergence, as I understand it, excludes deduction from the parts.

Emergence is an ill-defined concept so different fields have slightly different definitions; my assumption, without looking at the wiki page, is that it's from pure philosophy perspective. I come from the nonlinear sciences perspective in which we already classify properties as emergent. This doesn't mean that the properties can't be explained in terms of reductionism, but it's not always automatically apparent how the reduced interactions give way to the emergent properties, so it can't be predicted from the reduced "particle interactions" but once you've seen the phenomena you can start trouble-shooting it and seeing how the reduced particle interactions affect emergent outcomes.

Typical properties of emergent phenomena are degeneracy and distributed function, which further complicate said trouble shooting. Degenerate means several different kinds of interactions can lead to the same emergent phenomena and distributed means one reduced interaction may play a part in several different emergent properties. This makes troubleshooting hard. For instance, in biology, if you knock out a gene, other systems may compensate for it, so the effects you're seeing you can't directly contribute to lack of the gene as much as compensation by other protein networks. There's still a reductionist explanation, it's just obscured by the complexity of the system.

I would also agree with arildno that deducibility isn't really relevant.
 
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  • #10
arildno
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I'd say that "emergent" property would, for example, include a statistical deviancy in behaviour of a subsystem relative to statistical behaviour of the whole system.

But, it doesn't follow that that subsystem's deviant behaviour isn't in accordance with the principles governing the WHOLE system.

I would also emphasize ZapperZ's excellent reference.
 
  • #11
Diderot
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Pythagorean,
For instance, in biology, if you knock out a gene, other systems may compensate for it, so the effects you're seeing you can't directly contribute to lack of the gene as much as compensation by other protein networks. There's still a reductionist explanation, it's just obscured by the complexity of the system.
I would prefer not go there. I want to keep it 'simple': H2O, does it posses 'emergent' properties or not?. I take it from your answer that you don't believe in emergent properties [edit: with regard to water] of the irreducible kind.

ZapperZ,
Abstract: "In 1972, P.W.Anderson suggested that `More is Different', meaning that complex physical systems may exhibit behavior that cannot be understood only in terms of the laws governing their microscopic constituents."
My question isn't about complex physical systems. My question is about water. Boy, you must have missed the OP.
 
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  • #12
ZapperZ
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ZapperZ,

My question isn't about complex physical systems. My question is about water. Boy, you must have missed the OP.

I didn't! You asked this!

I wonder if the concept of emergent properties has become main stream in modern physics. If so, what happened to reductionism?

That's what I was responding to. Or are you saying that you're asking if emergent properties IN WATER has become mainstream in modern physics? This would be odd and highly restrictive, because, after all, why would "modern physics" worry that much about this very narrow application of water?

You asked a very broad question on emergent properties. I gave you not only a response, but also a direct, clear link.

You're welcome.

Zz.
 
  • #13
Diderot
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ZapperZ,
No, I asked this (you quoted correctly the first time):
What do physicists think about water as an example of something with emergent properties?
I wonder if the concept of emergent properties has become main stream in modern physics. If so, what happened to reductionism?
Let me rephrase my question: What do physicists think about water as an example of something with emergent properties? I wonder if the concept of water as an example of something with emergent properties, has become main stream in modern physics. If so, what happened to reductionism?
 
  • #14
arildno
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I'm sorry. But you continually use two WORDS "emergent" and "deducible", both of which can be given a number of meanings.
I'm sure that's not your intention, but that's hpw I read your posts.

For example:
Suppose the laws of interactions implies that a particular configuration of the small requires at LEAST 5 "particles".

Then, for 5-particle systems and beyond, THAT configuration may appear, but NEVER for particle systems of less than 5 particles.
Is that configuration an emergent property? I think it is.
Is it in accordance with the laws od interaction? Most definitely!

Is it LIKELY that a mathematician might be able to compute himself into all 5-particle configurations and be able to identify that particular configuration from his armchair? Not necessarily likely at all!
 
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  • #15
atyy
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Your question is ill-defined because it says "Emergentism. A property of a system is said to be emergent if it is more than the sum of the properties of the system’s parts." You need to clarify

(1) whether you mean a water molecule or a mole of water
(2) what you mean by parts
(3) what you mean by sum
 
  • #16
AlephZero
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My take on this is philosophically utilitarian, but it seems consistent with Anderson et al:

"Emergent" is no more or less than the fact that understanding a system "in the large" needs different conceptual tools than understanding it "in the small".

Of course as an engineer, I'm quite familiar with the joke about the physicist who tried to design some kitchen shelves by considering the behavior of the subatomic particles in the planks of wood. But that's exactly the point: classical continuum mechanics (described by tensor fields of stress, strain etc) is iIMO an emergent property of quantum field theory, and an engineer's "strength of materials" approach to designing cantilever beams is an emergent property of classical continuum mechanics. A mechanical engineer who designs a kitchen shelf by modeling the wood as a 3-dimensional anisotropic composite material is as big a fool as the apocryphal physicist.

The fact that historically the three models of the shelf were discovered in the reverse order is beside the point.

But I don't have any view on how that applies to the specific case of water. Sorry, water isn't my specialist subject
 
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  • #17
arildno
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"needs different conceptual tools "

"Needs" is a very strong word, AlephZero!
I'll stretch myself into "convenience", but "necessity"?
 
  • #18
Diderot
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Arildno,

My synonyms for the word 'deducible' are 'explainable' and 'understandable'. For instance the sentence 'some physicists hold the position that water has so-called emergent properties, which are in principle not explainable (or understandable or deducible) from the most complete knowledge of a lower level.'

Atyy,

Was it your intent to quote me? You didn't.
 
  • #19
AlephZero
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"Needs" is a very strong word, AlephZero!

Agreed, and that's the point, IMO.

Try understanding the behaviour of a chaotic dynamical system without using tools like Poincare maps or Lyapunov exponents, and see how far you get....

And I would call the Feigenbaum constant an emergent property.
 
  • #20
arildno
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Agreed, and that's the point, IMO.

Try understanding the behaviour of a chaotic dynamical system without using tools like Poincare maps or Lyapunov exponents, and see how far you get....
Isn't it, rather, constraints placed by reality upon such issues like computation time, rather than any LOGICAL need present here?

This is veering off into philosophy..
 
  • #21
Pythagorean
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There's no analytical solution to such problems. Numerical analysis is all that's fundamentally available. I would call that a "logical need".
 
  • #22
Pythagorean
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But this is where the line gets fuzzy anyway, because you can consider a reduced chaotic system or an emergent chaotic system, so I don't really know to what extent chaotic systems define emergent vs. not.

I guess even the reduced chaotic system can generate information in an infinite matter. You can zoom in on a basin of attraction forever, like those never-ending fractal movies. I don't know if that's all chaotic systems or not, but I think sensitivity (chaos) is a necessary condition for this type of "emergence".
 
  • #23
atyy
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Atyy,

Was it your intent to quote me? You didn't.

Yes, I meant to quote you. I now see you meant only to quote the snippet of the wiki article you linked, and not the article itself. So we are still left in the dark. Basically, until your define your terms, your question is meaningless.
 
  • #24
atyy
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My take on this is philosophically utilitarian, but it seems consistent with Anderson et al:

"Emergent" is no more or less than the fact that understanding a system "in the large" needs different conceptual tools than understanding it "in the small".

Of course as an engineer, I'm quite familiar with the joke about the physicist who tried to design some kitchen shelves by considering the behavior of the subatomic particles in the planks of wood. But that's exactly the point: classical continuum mechanics (described by tensor fields of stress, strain etc) is iIMO an emergent property of quantum field theory, and an engineer's "strength of materials" approach to designing cantilever beams is an emergent property of classical continuum mechanics. A mechanical engineer who designs a kitchen shelf by modeling the wood as a 3-dimensional anisotropic composite material is as big a fool as the apocryphal physicist.

The fact that historically the three models of the shelf were discovered in the reverse order is beside the point.

But I don't have any view on how that applies to the specific case of water. Sorry, water isn't my specialist subject

Agreed, and that's the point, IMO.

Try understanding the behaviour of a chaotic dynamical system without using tools like Poincare maps or Lyapunov exponents, and see how far you get....

And I would call the Feigenbaum constant an emergent property.

I do basically conceive of emergence in the same way you used it in the first quote. Emergence means that instead of using the "fundamental" degrees of freedom, we use different degrees of freedom and dynamics which are valid to "good" approximation only in our restricted regime of interest. So "table" is an emergent concept relative to electrons, and electrons are emergent relative to strings (in some universe, not necessarily ours), and strings are emergent relative to gauge theory via AdS/CFT.

But I don't see how the Feigenbaum constant is emergent in this sense - relative to what theory is it not fundamental?

Edit: I see your point, but can't express it clearly. I guess it's something like this? If the only observable quantity is the branching ratio, then the Feigenbaum constant specifies the ratio as long as one is in the right class of dynamical system. Which particular system in the class is unimportant, and those details can be thrown away. An analogous example would be that the ability to characterize a distribution only by mean and variance is emergent in any system where the observable is made from the sum of a large number of random variables. As long as one is interested only in the observable, mean and variance suffice and are emergent. (I think both the Feigenbaum constant and the central limit theorem are obtained as fixed points of a renormalization process.)
 
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  • #25
Diderot
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Arildno,
For example:
Suppose the laws of interactions implies that a particular configuration of the small requires at LEAST 5 "particles".

Then, for 5-particle systems and beyond, THAT configuration may appear, but NEVER for particle systems of less than 5 particles.
Is that configuration an emergent property? I think it is.
So, this configuration, being an emergent property, is not explainable (deducible) from the most complete knowledge of a lower level? Is that what you are saying?
 
  • #26
arildno
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Arildno,

So, this configuration, being an emergent property, is not explainable (deducible) from the most complete knowledge of a lower level? Is that what you are saying?
Not at all. But it means you'll need to jiggle five balls in the air in a clever way to perceive a particular new pattern.

Suppose that some effects only become perceptible as a form of behaviour (say, as a very rare condition amongst all the other possibles) when you have a zillion particles to juggle, and THAT effect only becomes PREDOMINANT when you have a zillion zillion particles to juggle with.

The effect is still in ACCORDANCE with the laws of interaction valid on the small scale, but predictable in practical computation time? Not very likely..
--------------------------------------------------------------------------------------------
In practice then, IF we regard "deducibility" to include within it "a reasonable time frame in order to make the computations from the basics", then such macrosystemic behaviour is NOT deducible; we'll always need, for practical predictive purposes, shortcuts to the answer, and the formation of concepts we do not strictly derive from the elementary laws. That does not, however, yet again, mean that the new concepts are in violation of those elementary laws.
 
  • #27
Diderot
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Your question is ill-defined because it says "Emergentism. A property of a system is said to be emergent if it is more than the sum of the properties of the system’s parts." You need to clarify

(1) whether you mean a water molecule or a mole of water
(2) what you mean by parts
(3) what you mean by sum
(1) at least 2 water molecules
(2) particles and laws; hydrogen atoms, oxygen atoms and relevant physical laws
(3) the abstract addition of particles and laws
 
  • #28
Diderot
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arildno,
In practice then, IF we regard "deducibility" to include within it "a reasonable time frame in order to make the computations from the basics", then such macrosystemic behaviour is NOT deducible;
So, you are saying that, in this case, an emergent property is not deducible within a reasonable time frame. So 'not deducible' - and emergence - has a practical connotation. An emergent property is not in-deducible in principle, because of reasons like: 'it is more than the sum of the properties of the system’s parts'; as in 1 + 1 = 4.
 
  • #29
arildno
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Well, it is the difference between my view of for all practical view of existent "emergence" and "indeducibility", and your view, that I regard as some sort of metaphysical claim about True Reality.

As to the latter, I don't see how either for or against it has any relevance in practice.
 
  • #30
Diderot
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Arildno, so you are saying:

Ok guys, let's declare this property 'emergent' because the client wants results before 6 o' clock this afternoon.
What does emergent mean boss?
Hey, don't worry about it, we are all practical folks and don't care much about the exact definition of terms
 
  • #31
arildno
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I think it is meaningless to bandy about with terms purporting to describe some aspect of reality but that cannot be checked whether they hold true or not.

Come up with an example where this theoretical "in principle" emergence will have different detectable results than my practical "in principle" emergence concept.

And no, my emergence concept is the precise one, not yours.
 
  • #32
atyy
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(1) at least 2 water molecules
(2) particles and laws; hydrogen atoms, oxygen atoms and relevant physical laws
(3) the abstract addition of particles and laws

If I understand you correctly, then water and all other phenomena in everyday life are not emergent in that sense. We believe that the fundamental laws (Schroedinger's equation for the interaction of hydrogen and oxygen) describe what we see everyday.

In physics, "emergent" usually means a relation between two theories. A more "fundamental" theory which is a good approximation over a "bigger" domain, and an "emergent" theory with different dynamical variables which is a good approximation over a "smaller" domain. An example of a fundamental theory would be one in which there are things like wood blocks, nails etc, and the emergent theory would be one in which there are tables and chairs. If you are arranging the furniture in a room, you can use the emergent theory of tables and chairs. But if you are a carpenter making a table then you use the fundamental theory of nails and wood.

One subtlety is that the carpenter must also know the relation between the theories, and part of the relation between a fundamental theory and an emergent theory is the concept of a good approximation over a smaller domain, where "good" depends on the user (the assumption that user is going to arrange furniture in a room, and not chop the tables up).
 
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  • #33
Diderot
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atyy,
If I understand you correctly, then water and all other phenomena in everyday life are not emergent in that sense. We believe that the fundamental laws (Schroedinger's equation for the interaction of hydrogen and oxygen) describe what we see every day.
Ergo, the so-called emergent properties of water, e.g. wetness, can be deduced from the most complete knowledge of hydrogen atoms and oxygen atoms and fundamental laws (Schroedinger's equation for the interaction of hydrogen and oxygen).
People who tell us that water has ‘emergent’ properties - properties which are in principle not deducible from the most complete knowledge of a lower level - are ill-informed. Water molecules are not more than the sum of its parts.
 
  • #34
Pythagorean
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even for a single hydrogen atom, modelling it with Schrodinger requires some liberties to be taken.

Talking about whether an ensemble of water molecules are "more than the sum of their parts" isn't meaningful. More what? Why are you summing their parts? What qualities do you measure to quantify that statement. It sounds quantifiable but it lacks quality.

You could find some properties of water for which it is true vs. not (probably something to do with extensive vs. intensive properties.)

And again, I have to agree with arildno that deducibility is a poor measure.
 
  • #35
Diderot
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Pythagorean,
Talking about whether an ensemble of water molecules are "more than the sum of their parts" isn't meaningful.
Not meaningful as in nonsensical?
More what?
Emergent properties! According to the theory of emergence water has emergent properties that are in principle not deducible from even the most complete knowledge of a lower level. These emergent properties emerge from nothing, they cannot be explained – at least not from a lower level -. These emergent properties therefor constitute the ‘more’. Due to these in-deducible (unexplainable) properties there is a whole that is more than the sum of its parts.
Why are you summing their parts?
In order to compare it to the ‘whole’ which is – according to emergence – the sum of the parts + *poof* emergent properties.
 

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