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Why do the forces of nature act on each other?

  1. Oct 22, 2011 #1
    why do fundamental forces of nature exist? Is it to attain a state of equilibrium? For e.g. is a positive charge is attracted to a negative charge to attain a state of equilibrium? Then why do forces like gravity, strong force, weak force exist?
     
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  3. Oct 22, 2011 #2

    mathman

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    I doubt if anyone can answer why. It is difficult enough to understand how.
     
  4. Oct 22, 2011 #3

    Chronos

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    Yes, 'why' belongs to philosophy.
     
  5. Oct 22, 2011 #4

    qsa

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    a better model should be able to do that. Nature is not magic.
     
  6. Oct 22, 2011 #5

    Pengwuino

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    There will ALWAYS be a point where you can't just say a better model must exist. Even the most fundamental theory of the universe, whatever that will end up being, will have to have assumptions built in and properties that are true simply because they are true.
     
  7. Oct 22, 2011 #6

    qsa

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    why not . This is how we made progress. Better assumptions lead to more usefull theories. Or at least more appealing ones.
     
  8. Oct 22, 2011 #7
    Eventually science will answer the "why". But there's still some way to go.
    When understanding is good enough, things are no longer "true simply because they are true". A deeper explanation always exists.
     
  9. Oct 22, 2011 #8

    Pengwuino

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    Can you logically show that deeper explanations can exist ad infinitum?

    Think about a simple math proposition such as [itex]5*{{1}\over{5}}= 1[/itex]. Why is that true? There's a couple reasons: inverse, etc. However, at the end of the day, you can't go beyond "it is true because humans created the system such that it is true".
     
  10. Oct 22, 2011 #9
    I usually hate these kinds of discussions because, in the end, everyone gets tied in knots and cries, "Uncle". Anyway, how would we know that we've uncovered the ultimate truth/theory of Nature? I don't think we can.
     
  11. Oct 22, 2011 #10

    Pengwuino

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    For the sake of argument, we don't even have to assume humans figure it out. It just has to exist. Then whatever it is, there's no reason to believe there would exist an explanation that you couldn't just say "why is this true?" to.
     
  12. Oct 22, 2011 #11
    I have to say though, it's cool to imagine a situation like that... like something (almost) unimaginably special that only in retrospect could we say "wow, there is no 'why' to that..."

    It's funny since I just read a transcript of a talk by Stephen Hawking where he talked about how he no longer thought a TOE was possible to uncover.
     
  13. Oct 22, 2011 #12

    Pengwuino

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    On the other hand, it's so sad when people stop asking "why?" so quickly. For example, I bet millions of students have been shown the model of the atom where... despite protons having the same charge, they all are shown bunched up in the center next to each other and none of them say "hey, wait a minute...".
     
  14. Oct 23, 2011 #13
    "why do fundamental forces of nature exist?"
    The force fields are emergent properties of simpler interactions between particles and photons (or bosons) acting over all possible paths and summed together.
    For example, there are more ways that an electron and a positron can interact which end up with a closer position than which end up in a farther away position. The path integral gives an expected attraction.
    So I think it is correct, if not fully descriptive, to say that all forces of nature are entropic. Gravity being less certain.

    Its a bit like putting a red and a green gas together and saying that there is a 'mixing force' which causes them to mix together. It isn't really a force, just the most likely outcome from the huge number of possibilities (random movement of the molecules in this case).
     
  15. Oct 23, 2011 #14
    but would it be wrong to assume that forces of nature exist to bring about a low energy state? (for e.g. strong force acts to bring about more stability).however more stability means less entropy.Moreover what is the reason for 4 different forces to exist , which ultimately leads to the same result i.e. stability ?
     
  16. Oct 23, 2011 #15
    I don't think it is right to think of entropic forces as existing in order to increase entropy or increase stability. I would say that they exist because that is the emergent result of less constrained rules acting in large numbers.

    By analogy I don't think that evolution exists in order to create fit individuals, they just happen to be the result of natural selection acting in large numbers.

    But its getting into interpretations, maybe you interpret differently. Several different forces because there are several different simple interactions that happen on different particles in different ways. I don't think anyone knows exactly why there are the specific types that there are, other than the quite weak argument that humans wouldn't exist if they were different by as much as a percent or two.
     
    Last edited: Oct 23, 2011
  17. Oct 23, 2011 #16
    nobody knows...yet.

    The standard model of particle physics does our best job of explaining
    three of the four forces(excluding gravity), and lots of the activities. But the magnitudes of the forces, the mass of the particles, the charge of particles, and so forth cannot yet be derived from first principles....they are observed quantities.

    Qantum field theory within the standard model does a pretty good job explaining most of what we know...but there are still unknowns.

    You could equally well ask: why does mass exist?? Why does our universe exist? Why do we?

    for more check out:
    http://en.wikipedia.org/wiki/Standard_Model
     
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