Action vs Reaction?

Discussion in 'Free Thoughts' started by Kumar, Dec 13, 2015.

  1. Kumar Registered Senior Member

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    Newton in 3rd law had mentioned "for ever ACTION...." not for every MOTION...". If so why we can't check every action has equal and opposite reaction in science, in whatever form that action may be. Like a wave, it always has both sides.
     
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  3. exchemist Valued Senior Member

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    Because they do not rely on objective (i.e. reproducible) observation and they make no predictive models of the natural world.

    These things are the essence of modern science and are what came to distinguish it from superstition, religion, philosophy and metaphysics at its birth after the European Renaissance.
     
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  5. exchemist Valued Senior Member

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    Newton's words are not a religious text. His laws are commonly called "Newton's Laws of Motion" because that is the best way to describe what they are in modern English and because that is how they are used, every single day, by thousands upon thousands of scientists and engineers throughout the world.

    Regarding his original words, you cannot pretend he was talking about something he was not talking about. Since you have apparently not bothered to read the link I gave you, I will quote the relevant passage from it directly for you:-
    QUOTE (from Wiki)
    Lex III: Actioni contrariam semper et æqualem esse reactionem: sive corporum duorum actiones in se mutuo semper esse æquales et in partes contrarias dirigi.
    Translated to English, this reads:

    “Law III: To every action there is always opposed an equal reaction: or the mutual actions of two bodies upon each other are always equal, and directed to contrary parts.”
    Newton's Scholium (explanatory comment) to this law:

    Whatever draws or presses another is as much drawn or pressed by that other. If you press a stone with your finger, the finger is also pressed by the stone. If a horse draws a stone tied to a rope, the horse (if I may so say) will be equally drawn back towards the stone: for the distended rope, by the same endeavour to relax or unbend itself, will draw the horse as much towards the stone, as it does the stone towards the horse, and will obstruct the progress of the one as much as it advances that of the other. If a body impinges upon another, and by its force changes the motion of the other, that body also (because of the equality of the mutual pressure) will undergo an equal change, in its own motion, toward the contrary part. The changes made by these actions are equal, not in the velocities but in the motions of the bodies; that is to say, if the bodies are not hindered by any other impediments. For, as the motions are equally changed, the changes of the velocities made toward contrary parts are reciprocally proportional to the bodies. This law takes place also in attractions, as will be proved in the next scholium.[32]

    In the above, as usual, motion is Newton's name for momentum, hence his careful distinction between motion and velocity.
    UNQUOTE

    It is plain he is talking about physical objects, not human actions. Furthermore, the laws were put forward in his work Philosophiae Naturalis Principia Mathematica, which was about physics, not metaphysics or human morality. You can read about it here (if you can be bothered): https://en.wikipedia.org/wiki/Philosophiæ_Naturalis_Principia_Mathematica
     
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  7. Kumar Registered Senior Member

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    Thanks for detailed explaination. But sorry, I feel we can not differenciate among different actions by us--either materialistically or energetically. It is another consideration that one we can easily measure other not. But it does not make other to be either invalid or impossible. We may have to base a prime basis of any law first then look at grosses. Prime basis in this case is "action causing reaction".

    Moreover, unless an understanding is absolute and final, that will just remain yet half cooked so can even be more harmful because people then will trust in those believing those as true. I feel, unless a scientific study is absolute and final and cove whole lifespan of its applicability, it will just be partly cooked.
     
  8. Kumar Registered Senior Member

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    As I thought in my last post, unless an observation/study is absolute and final, it then will also be like partly cooked food.
     
  9. exchemist Valued Senior Member

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    Nobody is talking about an observation being "final" or "absolute". And to be honest I do not find your food analogy helpful. An observation needs to be objective.

    This is achieved in science by the observation being repeated, independently, by different observers, in different places, and ideally using different methods, and finding it gives consistent results. For example, different people have measured the speed of light, in many different ways, and the results are in agreement with each other. This gives us confidence that it is what the books say it is - a constant, with a value of about 3 x 10⁸ m/sec.

    If we investigate a report from a farmer that he has seen an alien spaceship, we look first to see if anybody else reports anything consistent with what he says. And we look in particular for people whose evidence is likely to be good (air traffic controllers, airline pilots, military radar installations, etc). If we cannot corroborate it, we will be sceptical - it remains just another unconfirmed observation, and no scientific theory will arise from it.

    The importance of this strict requirement of science cannot be overstated. It is the filter that separates science from other, more subjective or speculative areas of human thought.

    The reason I was getting cross with you earlier is that you were trying to attribute non-scientific motives to Newton in his Principia. While it is certainly true that he lived at a time when science and other ways of thinking were still sometimes muddled up, he was trying in this work to think clearly about physical bodies or objects and work out the mathematical relations that governed their behaviour. That is all he was doing. He was not speculating about human actions, or morality, or making any point about yin-yang, good vs. evil or anything of the sort.
     
  10. exchemist Valued Senior Member

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    9,791
    I do not understand what you are trying to say here, but it seems to concern actions by humans. You are welcome to assert that human action causes human reaction if you like (I would disagree that this is necessarily the case, but never mind).

    Just do not cite Newton as supporting your point of view. Because that is emphatically not what he talking about in the Principia.
     
  11. Kumar Registered Senior Member

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    Anything still under on-going process can not be based without taking risk esp when that can have harmful effects alongwith. It is simply taking partly cooked food.

    Is it not true that when we say to any understanding a LAW, it should be universally applicable? Otherwise that can just be an specific and limited understanding(I don't know, what to name it). Moreover if all actions are not consistent with the Newton's 3rd Law of Motion will it not be more logical to define it as " for every physical motion there is an equal and opposite reaction" ?
     
  12. Kumar Registered Senior Member

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    1,990
    We can still try linking other actions with motion and with equal and opposite reactions. Let us take an example. In following animation you can observe motion is both way up & down but equal and opposite:-

    Here just consider, up side as action or positive side whereas down side as reaction or negative side. So this may suggest all positives will have equal and opposite negatives. Calculated centre line can be taken as a balanced state of positive & negative. On spiritual naming if I name up side as Angel state, down side as devil state and centre line as God state, I may not be absolutely illogical. OK?
     
  13. exchemist Valued Senior Member

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    No. It is not true at all. Are Indian laws applicable in Britain? Of course not.

    All laws have a scope of application - indeed these are usually specified in the law. As I said right at the start, Newton's laws are often called Newton's Laws of Motion . And indeed, you appear now to be demanding that Newton's Laws should be called Newton's Laws "of physical motion". Well , er yes, exactly. They are. And that's why: to define their scope of applicability.
     
    Last edited: Dec 17, 2015
  14. exchemist Valued Senior Member

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    See if Yazata will indulge you. I've had enough of you now.
     
  15. Kumar Registered Senior Member

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    Thanks. Last, why we can't link any action to motion?
     
  16. Edont Knoff Registered Senior Member

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    If you consider psychology, humans always misjudge their actions. There was a study to return a press or push in equal strength, still the candidates kept pressing or pushing harder and harder - so the perceived strength of incoming action is overestimated, and strength of outgoing action is underestimated.

    Thus newtons law is correct for physics, but not if the "action and reaction" pair involves thinking (likely even for animals which are not full able to think ... I'm tempted to assume that most neural control networks found in nature exhibit this bias).
     
  17. ajanta Registered Senior Member

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    We have to learn more.
     
  18. Kumar Registered Senior Member

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    1,990
    Ok, finally, can we take like it:-

    1. Action may or may not be related to motion.
    2. Newton's 3rd law of motion can better be defined as :"for every physical motion there is an equal and opposite reaction"

    Ok?
     
  19. Kumar Registered Senior Member

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    Fasting can encourage reaction i.e eating.
     
  20. exchemist Valued Senior Member

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    No, read the Wiki article I gave you at the start of this thread. There it states the 3rd law using appropriate terms from modern English scientific usage, rather than those of the nascent-scientific era of the 1660s. It goes like this:-

    "When one body exerts a force on a second body, the second body simultaneously exerts a force equal in magnitude and opposite in direction on the first body."

    A "body" in this context is a physical body, needless to say.

    You will gain nothing by searching for non-existent hidden meaning in the term "action" that Newton originally used. He used the language that he did purely because of the time at which he was writing and the fact that, at that, time, the definitions of the scientific terms we use today, such as force, energy, momentum, etc were not yet in place.
     
  21. ajanta Registered Senior Member

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    611
    Im learning about good and bad action. To developing medical science is good for human but going to bad for the ecosystem. May be the 'Real grand designe of the universe' can explain it properly.
     
  22. Kumar Registered Senior Member

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    1,990
    Ok then, what is the problem in using the correct terms in any old or obsolete definition?
     
  23. Kumar Registered Senior Member

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    1,990
    Probably, whatever which cause imbalances/odds in nature also become cause to balances that. It is action vs reaction.
     

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