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Riskanalysis in modelbuilding?

  1. Yes

    2 vote(s)
    50.0%
  2. No

    1 vote(s)
    25.0%
  3. Don't know

    1 vote(s)
    25.0%
  4. The question is unclear

    0 vote(s)
    0.0%
  1. Oct 19, 2007 #1

    Fra

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    [I wasn't sure where to put this thread, it might as well have gone in philosophy of science but I choose to put it here because it seems more targeted still?]

    I am curious about how different people consider the necessity of doing a riskanalysis when trying to make a fundamental model of nature and physics in particular.

    Just to illustrate what I mean, some examples.

    Trying to model reality is be it's nature risky business - we are often wrong, and what we "knew" was right, was LATER proved wrong, and needed revision. But consider that our life depends on it - we need an accurate model to simply survive. Then it would seem unwise to have no riskanalysis. It also seems crucial to test the most promising ideas first, and leave the less likely for later.

    To be wrong is not fatal, as long as we have the capability to respone and revise our fundaments promptly. Experience from biology shows that flexibility and adaption is power, so that when for reasons beyond your control, you are thrown into a new environment, there are two choices. You adapt and survive, or you die because you fail to adapt and your old behaviour was in conflict with the new environment.

    In history foundations are often revised or refined, so it still seems that flexibility is important.

    So, when making new models, that apparently take many many years, alot of both financial and intellectual investments... should we worry about what happens IF our models prove wrong? Obviously when they are wrong they are discared, but then what? Does this falsification show us HOW the old model should be modified? or does it jus tell us it's wrong and leave us without clue?

    The basic question is, should a new fundamental theory include a mechanism for self-correction in a way that is not pre-determined, but rather is guided by input? So that when it's wrong (because we are wrong all the time) we do not only know so, we have also a mechanism to induce a new correction?

    /Fredrik
     
  2. jcsd
  3. Oct 19, 2007 #2

    vanesch

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    I moved it to philosophy of science, as this really has not much to do with "BTSM" theories, which have absolutely no technological or medical impacts at all. The only "risk" there is a career risk, and that's not necessarily related to the correctness of the theory, but rather to its popularity at the moment of important career turning points :biggrin:

    Your point is actually much more to the point in phenomenological model building, such as is more the case in engineering disciplines, or medical sciences, where a wrong model might lead to wrong technological, technico-political or medical decisions, which are the only kind of "risk consequences" of scientific activities. Prime example: antropological climate change. There, errors in modelling and conclusions can have severe risk impacts. One or orther erroneous concept in string theory will probably have almost 0 impact, unless maybe on the careers of some people involved.
     
    Last edited: Oct 19, 2007
  4. Oct 19, 2007 #3

    Fra

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    Thanks for your comments.

    Perhaps my most fundamental point didn't come out. My main reason for elaborating "riskanalysis", is not just the risks to humanity if say string theory is wrong.

    What I mean to find out, is if a fundamental theory ought to have the property of self correction, in response to feedback (since IMO a theory is something that is emergent). Ie. should the theory itself contain a method or strategy of self-revision in case of an "observed inconsistency" or can we leave this revisions to human hand (which by definition is a bit ad hoc).

    My own implications of the question almost propagates down to the view of the scientific method in the sense that wether the induction of new theories, based on experience is part of science or not. In the typical poppian view, the focus is on falsifiability rather than "fitness" in adaption. The key points, is what is more important? and can we have something fundamental that doesn't reflect this? I guess my opinion is clear since I asked the question, but I'm curious about how others see it.

    So with riskanalysis I meant something deeper, not just riskanalysis in the context of human society, although that is certainly a valid "single example". But picture this riskanalysis generalised and abstracted, and it can applied to many things.

    I also associate this to the debate of background independent approaches. Ie. does it make sense from a fundamental viewpoint to have a background that can not change? ie that is not re-trainable? If so, what is the logic that has selected this background?

    /Fredrik
     
  5. Oct 19, 2007 #4

    Fra

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    Except for "direct damange", there is also the problem of scheduling of resources. It may not be fatal, but it may drag down our performance and "in the general case" will give competitors an advantage.

    But this thread is by no means intended to discuss research/funding politics! My intention it to bring the focus to the philosophy of the scientific method in a larger unified context.

    /Fredrik
     
  6. Oct 19, 2007 #5

    Fra

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    In the old days, a solid product that people need did the job.

    Now making investers think you have what they think the customers want you to have so they can expect a return is the new economy in a nutshell. Predicting expectations is more important that predicting what people really "need".

    One might wonder, why the life of en electron would be fundamentally different :wink: It's the expectations that governs life.

    /Fredrik
     
  7. Oct 19, 2007 #6

    Fra

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    I noticed the poll seems anonymous. Not that it matters much, but I was just curious. Most other polls to show ID of voters.

    Did I miss something when I submitted the poll?

    /Fredrik
     
  8. Oct 19, 2007 #7

    vanesch

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    Normally, you can choose yourself whether the poll is anonymous or not (before submitting it: you cannot change it afterwards of course).
     
  9. Oct 19, 2007 #8

    vanesch

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    Well, in my book, for the physical sciences, the "property of self correction" is experimental validation/falsification, and beyond that point, the meaning of the word "correct" is even not clear. In what way is a theory that doesn't make any falsified predictions "correct" or "wrong" ? I don't even think that the concepts of "correct" and "wrong" are uniquely defined for such a case. It's only in an observable context that these notions make sense - it is probably what the sarcastic comment "not even wrong" tends to vehicle. Say that my theory of the universe is "A H = 0". Is that theory right or wrong ? Now, replace this equation by 2000 pages of symbols. What has changed now ?

    Your remark is probably more to the point in mathematics. When is mathematics "wrong"? Obviously, when erroneous symbolic manipulations took place (sign error, ...). But is the axiom of choice "right or wrong" ? And when I give up on strict formal proof, but do "intuitive mathematics". When are certain manipulations "right" and when are they "wrong" if we already know that they are formally not correct (like interchanging integrations on divergent functions or something of the kind).

    To me, right or wrong in the end only have a definite meaning wrt observation: "you told me it was going to be sunny at 3 o'clock, and look, it's raining: you were WRONG."

    All the other rights and wrongs are to a point, matter of (social?) convention. So there are then two ways to make a theory be right or wrong: change the theory, or change the social convention.

    That said, I fail to see why you call it "risk analysis". Risk is normally "cost" times "probability". What's the cost of a wrong theory (wrong in what way ?) and what's it's probability to be wrong ?
     
  10. Oct 19, 2007 #9

    Fra

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    I think we are closing up on my point, thanks for your interest.

    This gets more philosophical now...

    Yes, I sort of agree but I make some what I think important distinctions here.

    Validation/falsification gives us information/feedback about wether a particular specific prediction/estimate is correct or not, it does not in itself define how this feedback is used to revise/tune our "predictive engine". This latter part is crucial ot learning.

    What I mean with self correction is that the feedback of the validations are explicitly used as input to the new predictions, this ensures that when we are "wrong" we will be sure to learn systematically.

    Without so, the only learning method is to randomly select another theory, or make a "random" or arbitrary perturbation of the predictive engine and try again. Such a thing is also valid, but would one expect as system complexity goes up, so does the sophistication of this feedback mechanism?

    Also, what does falsification mean for say an electron? Falsficiation/validation refers to human activies.

    What is the fundamental distinction between a validation following by a adjustment, and a plain interaction?

    Except the prediction and the verification were not available at thte same time :) I see it as making bets based upon incomplete information. The bet might still be correct, but the fact that it was later shown to disagree is due to incompletness of information. And the only fatal thing is to fail to learn! Depending on system mass an intertia, usually beeing wrong once of twice does not destabilise you, but if you consistently fail to adapt your predictive engine you will decay and not survive.

    A theory that is wrong AND fails to adapt is simply "wrong".

    A theory can is wrong, but contains a self correction to evolve on, and learn from it's "mistakes" or "incompletness" can still be fit.

    A theory that is right AND fails to adapt is just lucky! :bugeye:

    My personal conjecture is that this is bound to apply at all levels of complexity. Perhaps some misunderstandings is because you originally thought I was talking about human endavours and sociology. I am suggesting that these abstractions apply to reality itself. To spacetime structure, and particles.

    If you take the view of self-preservation. A theory that is wrong, or a structure that is in conflict with the environment will (I think) becoma destabilized in this environment and finally disappear.

    Try to picture a sytem, say an atom to be a "theory" in a silly sense. This atom will respone to new input, and if it is in reasonable harmony with the environment, it will be stable, if it fails to adapt (learn/change state) it will probably decay.

    This is alot of imprecise terms, and I appeal to your intuition. There is to my knowledge not yet a proper language for this. But I think we need a new foundation for a kind of relational probabiliy that accounts for differences in information capacity. A given observer can I think not objectively talk about existence of strucutres that is larger than what can fit in his own relations to the environment.

    So the probability spaces are I think bound to be relative too. This is why the notion of probability gets fuzzy. The probabiltiy itself can only be estimated, and subjectively so. The magic is why there is still an effective objective stable world? I think the foundational problems lies in self-organisation. These principles will yield to us the background we need for our theories.

    Does my point show, why I see falsification philosophy is a "simplification" and why the concept of self correction seems fundamental?

    /Fredrik
     
  11. Oct 19, 2007 #10

    Fra

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    To try to define the probability of something, by collecting statistics after it has happened is an akward thing IMO. This means the probability needs information from the future to be defined, this makes no sense as it's inaccesible to the observer to make his risk analysis. So the probabiltiy has to be estimated from the current information (what is retained from the past). But in this thinking, there is nothing thay guarantees the unitarity... ie. this expected probabiltiy need not be conserved, as the probabiltiy space itself is in possible evolution. If the observeed change does not fit the current structure and can not be accounted for by a simple state revision, the state of the state space needs to be revised as well. This is part of of my suggested "self-correction".

    /Fredrik
     
  12. Oct 19, 2007 #11

    Fra

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    But not all of the information of the past can be "retainable", because the observers capacity to hold and store is bound to be limited. The exception must be if the observer is growing, but it wold probably be gradually rather than a black hole sucking everything up.

    /Fredrik

    Edit: This may seem too obvious to mention, since this correction is exactly what scientists do. But this is done by hand, and outside of the formalisms. I want this feedback INSIDE the formalism, so that nature itself can be seen to have this builtin when we understand it a little better.

    /Fredrik
     
    Last edited: Oct 19, 2007
  13. Oct 20, 2007 #12

    Fra

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    The interest seems poor :)

    Vanesch, since you're the only one participating here:

    Do my posts come out unreadable and fail to make myself understood, or is people genuinely uninterested in these issues or consider them to be irrelevant to understanding reality and physics? :)

    /Fredrik
     
  14. Oct 21, 2007 #13
    Let's see,
    Model Building
    Its ability to adapt to error...
    Is this a requirement of a theory..?

    A metaphysical insight. In the ancient world, say 500-300 bc, metaphysicists Thales of Miletus to Democritis used to construct metaphysical blueprints of how they though the Universe was constructed. Each philosopher in a chain advanced, modified and rebuilt essentially the same template- that eventually led Democritis et al to postulate the existence of atoms...

    The underlying argument used by these thinkers was that there is simply too much knowledge, diversity wrt substance to formulate a grand solution. So that if there was to be a solution it had to come from first principles, an origin, a definition of how substance itself is generated. In other words, You begin with a definition of substance and then test to see if that definition accounts for what you know to be true, your knowledge base. Clearly, their models were simple, and necessarily had to adapt.

    It is interesting the way Aristotle considered each of their theories and then developed his own using logic. His attempt to define the nature of matter and substance is the foundation upon which our science is suppose to rest ( his definition of matter). You see, he would use intuition, logic and such to pursue a possible solution, often he ended in a contradiction, had to retrace his steps and then continued to investigate the nature of matter and substance along another avenue.

    I imagine that if one were to look for a more fundamental foundation ( a unified theory) in this way that it would be adaptable, and that it could be shaped by knew knowledge, phenomenon etc.

    My perception of science, is that it is fragmented, that each has a limit, some problem that each discipline tries to overcome. Just because a new phenomenon contradicts a specific theory or idea is, in my opinion, no reason to discard the theory as a whole. Certainly, if you have found some degree of success with a theory, then it is improbable that the original construct was entirely flawed. You have to ask yourself which portion, which idea holds true, and then adapt or try to overcome the phenomenological obstacle.

    A prime example would be the Bohr theory of the Atom. Although decidedly flawed, it was a valid theory because it did reproduce empirical facts, it did predict- but it had limits. Therein, and reluctantly so, Bohr conceded to quantum mechanics which inevitably absorbed many of the underlying 'acceptible' ideas of his model. It is my understanding that QT superimposes itself over Bohr's explanation of the H-atom and then exceeds it by reaching further.

    This ability to adapt seems reasonable to me. There is another mechanism that I don't prescribe to. You see, there have been theories that have been found to be limited, and which then expand to account for new discoveries. I call these catalogue theories. For instance, the immergence of particle physics was catalyzed by the discovery of the pion, muons, Kaons etc. The initial models accounted for these particles... The problem is that so many more particles or resonances appeared. As a correction, theories like the quark theory, which were initially limited to the number and type of quarks, simply added more quark types and or flavours to accomodate the data. In my opinion this is nothing short of a catalogue, since the quark theory is limited in its ability to be tested.

    This, of course, is my philosophical opinion and should not be taken as the fact. I keep getting warned not include my own non-peer reviewed ideas- but since this is a philosophical question pertaining to the philosophy of science, it should be ok...I hope.
     
    Last edited: Oct 21, 2007
  15. Oct 23, 2007 #14

    Fra

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    Thanks for your thoughts Sean. Your "own ideas" is exactly what I asked for. I make my own judgments so reviewed or not is a non-issue for me.

    You describe alot of scientific process as implemented by human history, and in that context it's almost needless to state that self-correction is part of the scientific process. To not adapt is the same as not to learn, or refuse to adapt evidence that does not fit in the initial assumptions.

    What I suggest is that the scientific method that analyses the self-correction part itself, and so to speak try to make a scientific analysis of the scientific process itself, and then try to formalise this into a model, which by construction will almost be a learning model, and strategy for optimal learning, and such a model would also have a much wider area of application than physics only, so the benefits for any efforts made in such a model will be quite large, further increasing the motivation. Basically try to model the modelling. And find the association of the modelling of the model, with how the physical evolution has taken place.

    My question was on the personal opinions of others that has reflected over foundational physics if a theory can fail to at least attempt to implement a decent level of learning power, can be fundamental?

    Obviously most theories, if not all theories we have do not do this. So clearly a theory doesn't need this, but then that's more of effective theories - fit in special cases.

    /Fredrik
     
  16. Oct 23, 2007 #15

    Fra

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    Maybe also a silly comment, but the evolutionary advantage of a self-correcting framework should be clear.

    Considering the computing power we have these days, intelligent dataprocessing (which I think what modelling is) would boost alot of progress, not only physics progress. This is why I tend to have a wider scientific interest than just physics. I find many physicists having a very narrow interest, and what "isn't physics" is apparently irrelevant to them. I like to understand reality and I don't care what the label is... but I am fascinated by biology as well, in particular the level of sophistican and "intelligence" and adaptive power that you see in single cells and how they respond to the environement. And not to mention the human brain. But my extended interest came to me, after the physics education... as a student I was a reductionist to mind... but when I started to study biology as part of a project I gained a new healthy perspective on things. I've always been philosophical but I am not "interested in philosohy" per see, except that the historical perspective on the philosophy of science is very interesting to read about.

    /Fredrik
     
  17. Oct 23, 2007 #16
    I agree, I majored in biochemistry and physics. So mostly classical physics. Chemistry, organic and inorganic gave me a powerful insight into how physics was shaped by their discoveries and how the structure of the atom was shaped by the chemical phenomenon of the elements. Molecular models are easy to visualize...

    I find it extremely frustrating how narrow minded quantum physicists are, to the point where they reject any philosophical perspective as to the foundation of science or even in the consideration of the underlying logic of their model. It's like they have their head in the clouds, electron clouds, and this prevents them from seeing any other alternatives.

    I don't trust theories, as I have mentioned, that continuously add operators or terms to acquire accuracy. Or theories that simply diversify to account for new data. I also think that a model should have a predictive quality of its own. For if a theory or model is to be successful, it needs to go further and predict more-even new facts about nature than the previous one.

    I've spent 15 years building subatomic and atomic models. In the beginning, there were lots of models. Eventually, there was just one. If I had given up on the way because of a mistake! In this respect, each new piece of data helps to shape a theory. A model can and will adjust if the underlying framework possesses at least some logic which is consistent with the nature of the constructs involved.
     
  18. Oct 23, 2007 #17

    Fra

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    I definitely wouldn't want to make it a general statement though to say that all quantum physicists are narrow minded :uhh: That's unfair.

    I'm sure there are equally narrow minded people in any are of interest. Perhaps it a matter of personality and may be depend on your relation to the subject.

    But in any case I see your point.

    I recall some excellent teachers of mine who was definitely anything but narrow minded, that impressed by their ability to immediately extract the correct questions in a cloudy context.

    /Fredrik
     
  19. Oct 24, 2007 #18

    Hurkyl

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    We already have a self-correcting 'theory'. It's called science.
     
  20. Oct 24, 2007 #19

    Fra

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    Sean, in order to understnad your comment - what is your take on QM foundations? Are you looking for a determinist interpretation?

    There is a book "Physics and Philosophy" by W.Heisenberg from 1958, which elaborates some of the philosophy around QM. It was a long time since I read it but I recall it was fairly interesting to see what the philosophical thinking was in the head of one of those who were around at the time when QM was founded. This is a pretty good perspective.

    For example, supposed I have issues with QM, then it's interesting to read the words of the founders and try to identify what, in the original context that is wrong. For example in another classic Dirac's "The Principles of Quantum Mechanics" both the founding points and the assumptions that are responsible for the problems are clearly stated, especially in the early chapters. At least from that book, it seems to me Dirac never have second thoughts about the objectivity and identification of a probability space. To me this is one of the key points to mention one thing.

    /Fredrik
     
  21. Oct 24, 2007 #20

    Fra

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    Maybe you didn't read all the posts?

    IMO, science is not a theory, and in particular not a formalised one. Our effective science is implemented using human communities and human intelligence, which certainly isn't that bad, but I think we can do better.

    /Fredrik
     
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