Your ideas on attraction and repulsion?

Discussion in 'Physics & Math' started by one_raven, Aug 23, 2003.

  1. Pete It's not rocket surgery Moderator

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    It's either fundamental or it's not - if an underlying reason is discovered, then the first reason wasn't fundamental, was it?

    If there are underlying reasons (discovered or not), then it's not fundamental.

    If a reason has it's own "why's", then it doesn't answer a fundamental "why".
     
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  3. Pete It's not rocket surgery Moderator

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    In this context, is there a difference between "why" and "how"?
     
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  5. lethe Registered Senior Member

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    science is a human institution. a theory is fundamental if it is the most basic, most widely applicable theory we have constructed to date. there is really no way to know whether a fundamental theory is truly fundamental, in some ill-defined "god given" "theory of everything" sense (although you can know a theory is not fundamental, you can never know if your theory really describes everything.) there are an infinitude of phenomena. at any time, a new one can show up, and invalidate your "fundamental" theory.

    so fundamental is really just a relative term.
     
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  7. Pete It's not rocket surgery Moderator

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    Hi lethe,
    The only thing I'd quibble with you about is the meaning of the word "fundamental", but that's not important.

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    Conceptually, I fully agree.
     
  8. lethe Registered Senior Member

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    i guess i know what you mean when you say fundamental. but my point is that at present, there is no theory which could really be called fundamental. i actually have serious doubts as to whether such a theory is, even in principle, possible (Gödel incompleteness and all that).

    for that reason, i don t really think it makes sense to say "It's either fundamental or it's not - if an underlying reason is discovered, then the first reason wasn't fundamental, was it?". i guess if we knew an ultimate fundamental theory, or at least had reason to believe that such a theory is possible, then we could agree that that theory would be the one that provides "fundamental" explanations, beyond which further "why" questions are philisophical. but since i don t believe that such a theory exists, and we certainly don t have one on hand, then i have to differ.

    according to your usage of the word fundamental, i would have to say that such a notion does not exist in reality.
     
  9. lethe Registered Senior Member

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    i would say that a "why" question should be answered by stating the foundations of a theory, whereas a "how" question should be answered with the dynamical details of a theory. but you can t answer a "how" question without knowing the "why". so if they are not the same, they are at least interrelated.
     
  10. Pete It's not rocket surgery Moderator

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    I think it's a valid, but unanswerable, philosophical question.
    My arguments could have been worded better. I too doubt that any theory can be absolutely fundamental; and if such a theory was possible the fact of its fundamentalness could never be known.
     
  11. lethe Registered Senior Member

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    agreed
     
  12. cephas1012 Registered Senior Member

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    What do people think of the idea that maybe these fundamental things are the way they are because they were designed that way? That is, the notion of a "god" or something supernatural being the cause.
     
  13. one_raven God is a Chinese Whisper Valued Senior Member

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    I think that God is irrelevant.
    A "God" of some sort may have been the initial cause of matter and energy coming into existence and the laws that dictate their behavior (the initial cause), but whether or not he is the initial cause things are the way they are now, and the existence or non-existence of a "God" will not change that.
     
  14. lethe Registered Senior Member

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    if you guys are going to start talking about god, i m leaving.
     
  15. cephas1012 Registered Senior Member

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    ok geez, sorry. I was just wondering what people thought of that as an "explanation". I take it you dont support that idea in any way, shape or form.

    Fair enough.

    A real question now. What would occur if the forces of charge were switched? What if opposite charges repelled each other, and like charges "attracted"? Would that cause a total break down of electircal force? I would think nothing could work the way it does if charge worked like that...

    Another thing, since we are on the topic of charge. I never did like that electrons were given a negative charge. I always thought it made more sense to say they had positive charge. Cause if you take away electrons from the valence shell of an atom it had a postive charge. I would think of that as negative since it had less charge from the electrons. But oh well...
     
  16. lethe Registered Senior Member

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    ahhh....

    well now cephas, you re talking. you have struck right at the heart of gauge invariance. ben franklin made the mistake of labeling electrons as negative, and protons as positive, because he didn t know about the nuclear model. he got it wrong, the natural choice is for electrons to be positive and the nucleus to be negative.

    however, which one you call negative and which one you call positive is purely a matter of convention. it is as arbitrary as which axis you call x, y, and z. the laws of nature are invariant under the reversal of negative-positive reversal. this is what is known as gauge invariance, and this simple principle implies all of electrodynamics. it is what implies that positives and positives repel, while positives and negatives attract.
     
  17. Pete It's not rocket surgery Moderator

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    Well, it's a bit unsatisfying, don't you think? It answers every question equally well, which is to say it doesn't give an explanation at all - it simply states that that's the way they are. It stifles the drive to look for deeper physical explanations.
     
  18. cephas1012 Registered Senior Member

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    This makes sense. I read what you said about this sort of thing in the higgs field thread. That is about all I understood from that thread, heh. I will have to try harder later.

    What i dont get is how the guage invariance implies "that positives and positives repel, while positives and negatives attract." I asked the question what would occur if positives and positives attracted, and positives and negatives repelled. I don't see any symmetry there. I would think you would get very different results, as oppose to if you just switched all the charged particles around and made positives negatvies, and negatives positives.
     
  19. cephas1012 Registered Senior Member

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    Hmmmm, ya, I see what you mean by that. Well when you get to the point that a question is truly fundamental and science can shed no further light upon the subject, you have two choices really. One is to say that is just the way our universe is. The other is to say something else caused this, that we cannot understand with science. So both ways offer the same result "- it simply states that that's the way they are." There is no way to prove either case, which is why when you get to this point it is no longer science. But in the mean time, you keep pushing to get to that point. There are still questions that science can answer, just because one says in the end it was made to be that way by "something" or "someone" does not mean you cannot keep searching. I guess that is all I have to say on this, and I will not say more, because some people dont seem to like discussion going this way, at least not on the physics and math section which I respect.
     
  20. lethe Registered Senior Member

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    i won t lie to you, the stuff in that thread is kind of advanced so it might take you a lot of study to understand. so let me sort of sum up the results, thus far:

    nature is symmetric under exchange of positives with negatives. antimatter with matter. therefore it is completely arbitrary which particle we call the electron, and which one we call the positron. you might just as well say that we are made of antimatter as matter.

    since distant galaxies are not causally connected to us (i.e. in places are so far away that it would take light-years for any signal to reach us, nothing that happens "right now" can have any meaning for us. in fact, the notion of "right now" is ill defined for distant galaxies). therefore we might make one choice and call electrons negative, while another galaxy will call their electrons positive.

    allow the choice between positive and negative to happen in a local, continuous manner, and you are led to maxwell s equations and the lorentz force law. which include the statement "like charges repel".

    so to answer your question, "could you have a universe where like charges attract and opposite charges repel?" the answer is no. the matter antimatter symmetry gives you only one choice.
     

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