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Are emergent properties real?

  1. Mar 28, 2013 #1
    I sometimes hear that some aspects of the macroscopic world are emergent. That is, some people believe that certain properties and laws (for example crystal structure, superconductivity, the conservation laws, Maxwell's equations, the laws of thermodynamics, the existence of momentum) could not even in principle be derived from a complete knowledge of the fundamental properties of matter and energy and the four fundamental forces operating according to QM and Relativity in space-time. Are such features really emergent? Or can all macroscopic features of the universe be in theory derived from fundamentals?
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  3. Mar 28, 2013 #2


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    Back up a bit. What have you read on this topic? Have you read Anderson's "More Is Different"? Have you read a series of essay by Bob Laughlin? And have you read the counterpoint to them by Weinberg?

  4. Mar 28, 2013 #3
    Thanks for the suggestions. No, I have not read those. My from-the-hip response is that more or bigger is not different in kind, only in quantity. That is, every quality that large scale structures possess is also possessed by small-scale structures.

    Here is the background to my question about emergent features or properties: I am trying to understand the origin of subjective experience and why some things in the universe (eg. rocks) do not have subjective experience while other things (eg. people) do have it. Some people, usually philosophers, psychologists and cognitive scientists, claim that subjective experience can arise as an emergent property from structures that do not have any subjective experience. They often give examples of what they claim are emergent properties: crystal structure, superconductivity, etc. I do not believe that these things are emergent properties. I have always believed that everything in the universe was not only reducible to physics but also derivable in theory from a thorough understanding of fundamental physics. So I am trying to see whether novel qualitative features or properties can in fact emerge. I don't think they can, but I'm willing to be convinced otherwise by evidence and argument.
  5. Mar 28, 2013 #4


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    OK, then we have an issue here.

    It is difficult to carry out such discussion without understanding the physics involved. That is why you have to read those sources because from what I have gathered, those are the giants in physics who are actively involved in such discussions. Otherwise, this thing will become a rambling based on nothing more than a matter of TASTES, which is philosophy, and that will immediately end this thread and discussion (see our PF Rules).

    Anderson's "More Is Different" is what has been credited to start the argument against reductionism. If you haven't read that, then you haven't read the genesis of this whole argument.

  6. Mar 28, 2013 #5
    Zapper you did a nice job by naming a few good sources to the OP and also me by the way to read about but let's not be that harsh whenever a question involves two words from philosophy even if the rest is pure science.

    If I understand correctly the Op's meaning of his question then I must say that , if you think about elementary particles having one set of rules (Quantum mechanics) and the piece of copper wire in your tv antenna a macro object even though consisting of QM objects has different properties then that fact alone won't help you much.
    Well if you mean derived from fundamentals as like explaining why the classical laws are the way they are because of what happens at the atom level or QM then no.
    Well i mean there surely is a path between them like magnet attraction or friction well you could draw some similarities between but mostly the macro world works differently than the quantum one.
    Why we have no clue.We just found out it does.
    Quantum tunneling is a good example search it up on google.
    Well you don't find cars "tunneling" walls or other stuff like hat in real life.
    Now emergent they are from QM world they are just not the same that's all but yes without the first there would be no second so in that kind of sense yes they do emerge.Just like a river emerges where alot of little water droplets fall at the same place.
    As for human consciousness physics is not much of a help because at the quantum level you are no different than your surroundings a metal has electrons you have too , water has atoms you have too and human is mostly made out of water so...
    Only when you go higher were fluids and substances and macro things start to form only hen you get some differences between let's say you and a chair and even those are not explaining why we have consciousness.
    Actually according to the theory of evolution we evolved out of non organic matter , cosmic dust literally to be exact and as far as we know cosmic dust , planets , stars or a fridge doesn't have or share any consciousness at all.So again pretty much dead end.
    The only way according to evolution something of a common sense or understanding could have emerged is by living together for a long time realizing that some things we like better and some not for example a wife loves to be treated with care rather than hit with a bat or any other object in the house.Now as simple of an analogy that is it is basically the way our theory of life origins explains it.You have brains and nerves that can feel sensations and translate them to brains so then they know which ones are good for you and which ones not and years after years you learn which ones you like and which ones you don't and then after many many years people living in a tribe come to realize that there is a certain way of living together that is better than the other and then they write down what they think and laws emerge and so on.
    If you ask me personally there is alot that doesn't stick and I don't accept it based on experience I have had and from much I have read but I cannot discuss that here.

    Now ofcouse philosophy would have to say an awful lot about this but then ZapperZ would close this thread faster than Chuck Norris would blink an eye.And from a point of view it is good as if you want to understand something specific rather fast it is better to talk only in the lines of that discipline although there are cases when philosophy is a must otherwise science starts to sound unreasonable and quite frankly idiotic and sometimes even smart academic intellectuals like Lawrence Krauss and others are talking facts +fiction because wherever there is a man there is also a biased subjective opinion or his consciousness so well...
    Last edited: Mar 28, 2013
  7. Mar 28, 2013 #6


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    Whoa! I let two words from philosophy slipped through? I must be losing it already...

    Not sure what exactly you wrote here.

    Note that a "macroscopic" phenomenon such as superconductivity is also purely a QM phenomenon. It is just that its ground state is a many-body system, not a "single-particle" system. This is why it is an emergent phenomenon that isn't derived based on considering all the interactions at the individual particles involved in the system.

    So this isn't just a matter of size scale.

    Also a note to the OP: "More is Different" isn't just a philosophical issue or simply based on a matter of tastes. It has experimental and empirical justifications. See, for example:


  8. Mar 28, 2013 #7
    is this philosophy?

    An ant & it's colony. me and my individual cells.

    Was that in the "more is Different" essay?

    "The whole is greater than the sum of it's parts." Aristotle 384 BC – 322 BC

    yea philosophy is terrible, what next; debate what Aristotle meant?

    Unless the op is questioning the continuity from micro to macro.
    Last edited: Mar 28, 2013
  9. Mar 28, 2013 #8
    I don't understand this definition of emergent.
  10. Mar 29, 2013 #9
    @nitsuj everything can be terrible either if you don't understand it or use it the wrong way.
    A single ant and a colony doesn't change in terms of properties rather than behaviour , just like a single car or a car park , because they all are already macro objects , the OP was asking about the transition between micro and macro.

    @ZapperZ yeah I didn't understand what i wrote from the place you quoted me myself because it was before going to sleep I guess I should be more careful with the late night posts :D
    But the fact that quantum systems are related to macro systems but they not necessarily work the same way I would say.Well atleast not in all cases.

    Now this all may seem quite easy and so up until the OP asked in his second post about consciousness experience now that not only complicates things it also now stands between philosophy and science as quite honestly I don't know who will be able to explain consciousness fully with either QM or classical or something from the field of science at all.
    Now human body does have nerves which act as like tiny electrical wires sending signals to muscles and receiving them back to brain to understand where and what has touched you and so on and that's how you feel and it is part of the conscious experience but is that the only part I let some others explain this here and then see what i have to say if anything at all.

    @diegzumillo a simple google search would have revealed you that emergent is something that comes into existence or one observers sight or so on.The dog that frightened you back in the day possibly emerged from a street corner, you never saw him before.
  11. Mar 29, 2013 #10


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    Very interesting read is also this book by H. Primas which is quite a classic:

    Title: Chemistry, Quantum Mechanics and Reductionism: Perspectives in Theoretical Chemistry
    Author Hans Primas
    Edition 2
    Springer London, Limited, 2011
    ISBN 3642693679, 9783642693670
  12. Mar 29, 2013 #11


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    Bob Laughlin wrote a whole book on the topic of emergent phenomenon:

    "A Different Universe: Reinventing Physics from the Bottom Down"

  13. Mar 30, 2013 #12
    I read A Different Universe by Bob Laughlin. Worst book ever. Terrible writer. 95% stories 5% science. I don't even know what he was talking about half the time because theres so many small stories every chapter. just saying. And the book was if favor of emergence.
  14. Mar 30, 2013 #13
    Crazymechanic mentioned Quantum tunneling....

    ...which made me wondering... But it's possible that a car tunnels through a wall, right? ... it's just very, very unlikely... It would happen if all the particles forming up that car would be properly 'set up'.

    What if transition from micro to macro just appears to be strange, while in truth it's all just about probability? Where objects like a car compared to an object like an electron surely has to interact differently in its surrounding due to probabilities vastly changing by number of particles involved ...

    Please don't close this thread down, if my post fails PF standards, just delete my post.

    Update: Just ordered Kindle version of Anderson's book "More Is Different".
    Last edited: Mar 30, 2013
  15. Mar 30, 2013 #14
    What I mean to say, more politely, is that the usual definition of emergent (that I'm aware) has nothing to do with the original post. Example: thermodynamic properties are emergent from the microscopic behavior of its molecules. But thermodynamics can definitely be deduced from the former using statistics.
  16. Mar 30, 2013 #15
    @Boy@n Well it is indeed about probability but in macro world it is as to my understanding never recorded that something other than a bulldozer would go through a wall in a tunneling style performance.
    A macro object just has too many micro objects and states for them to be in the same position all at once.I think it is fair to say it is impossible.Now the thing about the probability is more just because we can't keep track of all the information that's why it is a probability , a particle knows where he is ...if we could simultaneously know each state and position of each particle we could calculate the chances of "winning"
    Even though I'm not perfectly sure what happens with macro objects close to absolute zero or at absolute zero as the states then are equal = lowest possible so maybe then there are some exceptions.

    @diegzumillo actually statistics is the properties of the majority and this goes also as an answer to why cars don't tunnel through walls without getting crushed because the majority of particles that make them up are not in a state that could allow this.
  17. Mar 30, 2013 #16
    If I may... I'd like to reverse the question...

    Is anything else than emergent property real?

    ...with this question I have "consciousness" in my mind, as it's the sole thing which makes reality real for each of us, in however way each of us perceives and experiences it...

    I see our self-aware consciousness emerging out of our physical brains... but how that happens I know not (it seems though, that number of connections among neurons is just not enough, or we might say Internet is already self-aware).

    Science surely helps us a great deal to understand our reality better and better, but we are still limited to our human ability of perception and comprehension... where proper definitions are the first obstacles to go deeper in understanding and communicating it. (To not mention personal agendas, emotions and beliefs.)

    What is real? What is consciousness? Is our reality really just a very sophisticated simulation?

    (IMO this thread is quite "entangled" with this one.)
    Last edited: Mar 30, 2013
  18. Mar 31, 2013 #17
    Well you said it yourself and I strongly believe that ones consciousness is not the whole reality nor can one perceive the whole reality or the "truth is out there" or even not the whole of laws and events and phenomenon behind nature.
    the fact that most of the phenomenon in physics we get to know with some kind of help of apparatus or devices or just by probing what is left from what was once there like the light that tells us about the beginnings of the universe itself.
    Now one simple thing come sin mind is that different humans have different hearing ability.
    Ones can hear up to 20+ khz of sound but some can only hear like up to 19/18 Khz now also the upper limit decreases with age but just because ones consciousness cannot hear the sound or "feel"the sound that doesn't mean the sound is not there.
    Our consciousness is severely limited so not the greatest tool out there and also a drawback whenever it get's to understanding the depths of physics or the "way nature is"
    That's why we have tools that our consciousness understands like math which helps us understand the nature around us but again is nothing more than a human construct.

    Great words about the "internet self aware thing" Yes nerves and signals traveling through them doesn't make a consciousness there is something more but I believe that is beyond the scope of natural sciences and some modern day scientists even dismiss it as non existing but I'm not in the same boat with them on this case as I believe that it is rather impossible to try to explain the whole mechanism from a viewpoint of a single screw.It's rather a choice than a proof.Now in real science we should avoid choices we should only stick to the facts and figures that we can prove and stay shut about what we think is real or not or what we think exists or not and this goes out to all the creationists just as well as all the atheists as they both have the right to facts but not the right to opinion when it is pure science debate.
    Too bad many front people of the science community bias their and societies opinion with what they "believe"in but cannot prove.

    So as on a post in a natural sciences forum I can only say to you that we don't know atleast not yet and if you ask me personally I doubt if ever , whats is consciousness to the full extent of the question.
    To what is real I would say philosophically that it is something your consciousness cannot encounter directly only through other means and yes a touch or eyesight is not real it is only a means of receiving information and decoding it so that we could understand it.
    Now answer me a rhetorical question , has someone ever seen light?

    this video may help answering it. :)
    Last edited by a moderator: Sep 25, 2014
  19. Mar 31, 2013 #18


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    The term "emergent" is not defined by anyone in the physical sciences, it is defined by philosophers of science such as Bedau, Emmeche, Chalmers, and many others. There is a distinction made between 'weak' and 'strong' emergence which has a bearing on your question.

    Strong emergence requires downward causation but weak emergence does not. Downward causation is the concept that new physical laws come into being as we look at larger systems of things. Some of the physical laws you refer to provide a good example, especially thermodynamics and similar laws such as the Navier Stokes equations. The question would be whether or not the physical laws which describe thermodynamics or fluid flows can be derived from the underlying interactions between molecules or not? In other words, are the Van Der Waals forces and interactions between molecules at the small scale sufficient to describe phenomena such as Rayleigh Benard convection, or are there other physical forces that emerge from those interactions which can somehow over-ride those lower level interactions? I think Davies describes this brilliantly when he says:

    Davies could be talking about a paper by Bishop for example, who suggests that these low level laws are necessary but NOT sufficient to describe Benard convection. Bishop suggests that additional physical laws ‘emerge from’ the interactions and that these additional laws govern the overall phenomenon such that without them, convection cells can’t form. Clearly, Bishop is in the minority among physicists, engineers and scientists. Mark Bedau’s conception of weak emergence is all that is required IMHO to explain how convective cells emerge from the Rayleigh Benard instability. I believe Phil Anderson’s conception of emergence is consistent with weak emergence.

    The question of whether there are ANY strongly emergent physical laws is a good one, but to understand that I believe one needs to understand what the separability principal is all about and how classical mechanical systems are characterized by being separable while quantum mechanical systems are characterized as being non-separable. Condensed matter physicists often argue in favor of there being strongly emergent physical laws which can’t be derived, even in principal, from the underlying physics, but this is a special case of phenomena which are non-separable. Phenomena that can be described by using classical mechanics are always separable and are never strongly emergent. They are only ever weakly emergent but that may not necessarily be true of non-separable systems.
  20. Mar 31, 2013 #19
    From the POV of empirical science, there is not only a lack of proof of consciousness, there is no clear definition. So, empirically, in terms of what objectively exists, it doesn't even make sense to discuss it! Alternately, from POV of one subject's consciousness, empirical observations are merely aspects of conscious experience "whatever THAT is." Moreover, even if all of the natural behaviors one person attributes to consciousness "out there" are emergent via chemistry, biology, evolutionary selection - then we are still describing a universe where subjectivity per se is not observed ("can't ever be by definition") and thus can't be described as "emergent."

  21. Mar 31, 2013 #20
    @Q_Goest quite nice post there , to add , well here you say quote

    "" ""Davies could be talking about a paper by Bishop for example, who suggests that these low level laws are necessary but NOT sufficient to describe Benard convection. Bishop suggests that additional physical laws ‘emerge from’ the interactions and that these additional laws govern the overall phenomenon such that without them, convection cells can’t form. """

    Well to put this in a simple perspective we could use people and society.There are some laws that govern people when they are alone , some common things upon every individual that are theirs when they area alone, now when someone goes out and meets other people and even more when people come together in large groups like political party sessions or some public concerts or workplaces etc. some other common laws start to emerge and the behavior of people changes upon their interaction.
    So interaction causes change and a different set of properties emerge to some it is more to some they change less but basically everybody's different in public than they are when alone.
    So interaction causes some set of new rules.Now I think most would agree to this and psychology has studied it alot in various different ways.Now in physics there is something similar.
    Upon interaction you get what you don't get otherwise.

    the question then becomes are laws only the ones which are fundamental to everyone at the most basic level of their state (in the human case being alone) or are laws also the ones which emerge from interaction and which are observable only when interaction occurs.

    @1977ub I would rather say that we can't observe objectivity because every law of maths or science or politics ever written and said every revelation or understanding about the world around us ever said has come from the person who said it and the person was obviously a man and he had a consciousness which he himself couldn't understand rather only encounter so there is no objective reality that we can see or understand , well I believe there is one but it is literally hidden from us and we see only the glimpse of it.
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