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Newton's work on fluids

  1. Jan 15, 2012 #1
    Why is Newton's work on fluids rarely cited? And when cited it is not usually credited. Even If they called it a 'Newtonian fluid" they don't bother telling everything Newton did.
     
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  3. Jan 15, 2012 #2

    Simon Bridge

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    Why should it be? Generally, Newton's work is so famous it seldom needs to be cited explicitly. You'll find the same with other famous work. You'll see mention of "Ohmic resisters" for eg. but Ohm's work isn't cited and neither is the rest of his work discussed when we are talking about electric circuits and he didn't do nearly as much of significance as Newton did.
     
  4. Jan 16, 2012 #3

    AlephZero

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    One good reason is that much of what Newton wrote about fluids (e.g. in Principia) falls a long way short of modern understanding of fluid behaviour, and some of it is just plain wrong.

    Newton didn't have a concept of "energy" in the sense later used in classical physics. Fluid mechanics didn't really get started until basic ideas about energy were sorted out - i.e. until the time of Bernouilli, Pascal, etc.
     
  5. Jan 16, 2012 #4

    Simon Bridge

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    ... and we don't tend to cite these guys more than briefly either ... also too famous, too basic. When you have physical principles named after you you don't get or need explicit citations. One of the advantages of fame.

    I think we need more context from OP - where is this coming from?
     
  6. Jan 16, 2012 #5
    In my 'physics 2' It wasn't even mentioned Newtons treatment on fluids, something the seemed to repeat everywhere.
    After a while I decide to read Principia and I was amazed by how Newton modeled things by very simple(although often very lengthy), intuitive and powerful arguments(a 'feynmanesque' thing). Principia gives a much greater 'feel' of his laws and way of thinking(although I'm having some problems with some terms meaning) than modern textbooks, and I found his take on fluids very interesting. I think that it would be worth to transfer his original arguments to classroom somehow, to give a better glimpse at how the reasoning looks like before all its trimming(which usually takes of much of the 'feel') through time.
     
  7. Jan 16, 2012 #6

    Simon Bridge

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    Ah right - in the context of teaching a course in physics, we don't use Newton because he was wrong or his descriptions were unhelpful. Principia is not a helpful text for learning physics any more - read as a historical document only.

    Note: there is a school of thought that likes to return to "first sources" for knowledge. This works for revealed or discovered knowledge/thoughts like in historical documents, which may have been altered or mistranslated since written.

    However - science does not work like that. The original sources for much of established science is wrong in some important way - not so useful for learning how the World works.
     
  8. Jan 16, 2012 #7

    boneh3ad

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    AlephZero gives a good answer. Additionally, a lot of Newton's conclusions about fluids were just plain wrong. They do, as it turns out, give a miraculously accurate estimate of certain quantities in hypersonic flows, but in general they aren't at all correct.
     
  9. Jan 31, 2012 #8
    Anyway, I have the impression that some of these original books gives us some ideas about how all the dirty guess work behind science really is.
    I've noticed that professors usually just bash simple and mundane constructs to made by students to model phenomena(not as if discovering a new thing, but more like a mental exercise) as "obviously wrong" simply because they are "ugly". I gladly saw that while very old models of nature, like those of the Greek, are usually considered coarse by everyone today, recent geniuses also made very practical and "mundane"(maybe on their time it was not) approachs to physical problems, like these on http://en.wikipedia.org/wiki/Mechanical_explanations_of_gravitation that even being wrong, show that whatever testable explanation you have makes some sense to you, you should analyse and test it until it turns to be impossible, as mundane as it may look. And whoever claims it to be "nonsense" should be able to immediately show it to be impossible.

    I heard a nice thing from William Shockley the subject

    http://www.youtube.com/watch?feature=player_detailpage&v=LWGVuoisDbI#t=356s

    Also, a good invalidation of a model is also science. I like that phrase from Bhor:
    "An expert is a man who has made all the mistakes which can be made, in a narrow field."

    He probably got his quantum concepts after ruling out all other models. It was too counter-intuitive to be one of the first guesses.
     
    Last edited: Jan 31, 2012
  10. Jan 31, 2012 #9

    Simon Bridge

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    Sure - but that's no reason to go cite the work is it?
    You are just saying that they are useful as historical documents - and this would be correct.
    You'll probably find Newtons works about fluids cited in historical treatments of science as sociology.

    Teaching exercises are there for pedgogical reasons. When students get to grad-school (and as senior undergraduates) they are brought into contact with the nitty gritty of real scientific research. Until then, they are not being taught science all that much but being taught about science. So examples and models are presented in a way that highlights those features that are currently important to the students education. There are time and money constraints to this process - something is going to get left out. I think pedagogical models are a different subject.

    Actually - the "quantum" part was constructed over a time from accumulated observations. The mathematical framework had been around for a while, and the lynchpin apparently appeared to Schodinger in a dream or something. So it was at least intuitive to Ernst. QM is called "counter intuitive" not because it makes prediction that are the opposite to what we'd usually expect from everyday experience but because the real universe is really like that. What we today call "quantum phenomena" would still be counter-intuitive even if there was no QM to describe it. It is highly unlikely that Bohr actually tried out every possible alternative available before settling for QM.

    QM is one of those things that is "obvious in hindsight".
    See, for example: Scott Aaronson's treatment
     
    Last edited: Jan 31, 2012
  11. Feb 1, 2012 #10
    What is the "cost" of citing it? You seem to suggest that showing examples of how building and refuting models is like has no didactic value. I totally disagree, at least when it comes to students majoring in physics. They could be optional subject but even a quick pass on them would be of value.

    In high school it is usually told about the evolution of atomic models almost as anecdotes. Two things high school teachers usually have no knowledge to handle any argumentation of students and often teach things wrong, and students also don't have much knowledge to argument on that.

    In college we have much more knowledge and tools to seize this kind of thing and also we are being taught by people who could give any details on that. Yet, we only see brilliant and correct ideas appearing out of thin air, which is nothing like real problem solving.

    Also, since you told about grad-school showing about research, do they show historical wrong models there?

    Well, I don't know which mathematical framework you're talking about. But mathematical tools mean nothing if you don't know if they can be of any use, and you won't know that until you have got data that suggests that(and you must test it). And in great part whoever invents them was just solving puzzles which they didn't know could be important. Hardy was proud that his work was useless. Recently some of his works on number theory were used in crystallography if I'm not mistaken. That doesn't mean he 'foresaw' the behavior of those 'crystals'.

    What?? That's the definition of counterintuitive. Both QM and the observed behavior of nature at small scale are counterintuitive as far as we can tell. If we happen to make an intuitive model which describes nature at small scales we wound consider the nature in small scales intuitive too, but we still won't be sure if the model is right(we can't possibly know, philosophically). So you can tell how 'counterintuitive' nature is, only how counterintuitive it seems, but that is a consequence of of the best mental model you got to understand it. And accounting for amount of heavy weight physicists, Einstein included, that stood with the "realistic" approach to quantum mechanics it is highly unlikely that the leaders of the 'copenhagen interpretation' didn't make a long meditation on the realist possibilities.

    Interesting quote. I plan to try to 'understand'(as be able to use) QM in a near future, I see this guys material.
     
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