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Why magnetism exists?

  1. Aug 15, 2013 #1
    Hi, im 15 and I got interested in this question. My question is not how magnetism exists, it is WHY magnetism exists?

    Thanks
     
  2. jcsd
  3. Aug 15, 2013 #2

    Dale

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  4. Aug 15, 2013 #3

    micromass

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    Science does not answer questions like that.

    Some things to watch:

    https://www.youtube.com/watch?v=E383eEA54DE

    https://www.youtube.com/watch?v=KLoNA9lMb6A
     
  5. Aug 17, 2013 #4
    Out of these videos and some more research, I found out that modern science cannot answer this question or physics cant answer this question at this level of undrestanding of the universe,
    we possibably can answer this in the future, am I right?
     
  6. Aug 17, 2013 #5

    sophiecentaur

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    Like Feynman says, the 'why' is never answerable because you can choose any level at which to answer that question. All that real Science tries to do is to describe 'how' something operates i.e to give a model which gives predictions about the way things will turn out in as accurate way as possilbe.
    The answer to 'why', for early Science and Philosophy was always, ultimately "because God made it to work that way". i.e. God's Laws. That is not the approach, these days - at least not for Scientists.
     
  7. Aug 17, 2013 #6

    Nugatory

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    Everyone is of course correct that science eventually runs out of answers to the infinite regression of "why?" questions.

    Nonetheless, Original Poster might be interested in the way that magnetism can be made to emerge from other stuff that we accept, such as electrostatics and special relativity. Googling around for "Purcell magntism relativity" will find a bunch of good stuff, for example http://physics.weber.edu/schroeder/mrr/MRRtalk.html
     
  8. Aug 18, 2013 #7

    sophiecentaur

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    That 'explanation' is particularly good fun, I think. A real bit of theoretical 'anarchy' to challenge what we were all taught at School.
     
  9. Aug 19, 2013 #8
    It's anarchy with beauty and elegance, the best type of extrapolation.

    It seems to have a vast number of applications, as I'm sure the authors of that book mentioned in the link must know. The point charge in motion drawn with the field lines reminds one of a path of least resistance concept vaguely, so perhaps it can be applied to motion generically. This doesn't sound too fun, but well, the special relativity ideas are solid and worked out already. What would be really interesting would be to generalize these magnetic results of an interpretation of sr to gravity, and see what comes of it. It's a rich train of thought, how the author presented the matter.
    But as to why magnetism exists, that is answered when one knows how gravity and it mix, with the rest of the factors as well. Gravity in general relativity is a geometric entity, the space pulling and pushing matter around, and the magnetic field is successful and graphic, but I think? gr is technically a field theory. So magnetism may eventually be explained in terms of geometry, with everything else (that's the big hope anyways), and then there could be some deeper reason as to why it arises, and how it relates to other entities. Talking vaguely now, there are quite a few people that think the use of probabilities, as very successfully shown by quantum experiments, is to be explained by some as yet unknown theory in which these things are not so random. Perhaps, then, magnetism and gravity are very closely related and a part of some underlying theory. If the case is that this is geometrical, then magnetism may come from those set ups, or be called for as a consequence of that relation.
     
  10. Aug 19, 2013 #9

    CompuChip

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    Thanks Nugatory, just posting here as a reminder to study that link carefully sometime.
     
  11. Aug 19, 2013 #10

    phinds

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    Did you actually watch the Feynman video? He doesn't say we can't answer the "why" questions because we don't know enough, he says we can't answer them because they HAVE no answer in any fundamental sense.
     
  12. Aug 19, 2013 #11

    Dale

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    Not through science. Not ever.

    Sometimes when someone asks "why X" they actually have a more specific and answerable question in mind, which is the reason I asked for details above. However, as posed, why questions are generally non-scientific (what test can you perform to measure "why"). Answers generally are the purview of religion or philosophy.
     
  13. Aug 19, 2013 #12

    WannabeNewton

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    In a good number of honors EM classes for freshman in the US that is how it's taught.
     
  14. Aug 19, 2013 #13

    WannabeNewton

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    GR doesn't explain what gravity is any more than classical electromagnetism explains what magnetism is. Just because we cast something in geometric form doesn't mean we have explained what it is, far from it. I could just as easily ask "why is gravity a manifestation of geometry?" and we would be led down the same pointless road again.
     
  15. Aug 19, 2013 #14
    On a somewhat positive note, electromagnetism, the strong force and the weak force have been 'unified' in the Standard Model of particle physics.....that is combined into an overall mathematical framework. Off course that does not explain 'why' any are present, just some insights on how they fit together.

    Offsetting that somewhat 'Pollyanna' view is that the Standard Model and it's quantum field theory falls short of being a complete fundamental theory....it's a bit of a' hodge podge' [miss mash] .....missing some ingredients like gravity, dark stuff [95% of the mass -energy in the universe] , and a lot of other basics, like the mass and charge of the electron....Is it 17 parameters that are experimentally measured rather than theoretically derived?? Something like that number.

    Oh well, still lots of room for more discoveries even if 'why' eludes us.
     
  16. Aug 19, 2013 #15

    ZapperZ

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    Coming back to you original question, magnetism exists because electric field exists.

    Zz.
     
  17. Aug 19, 2013 #16

    HallsofIvy

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    The gods of the blue continuum created "magnetism" as a weapon in their on-going battle with the gods of the red continuum!
     
  18. Aug 19, 2013 #17

    sophiecentaur

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    Whether there is an ultimate answer to the "why" question is a matter of faith. It has nothing to do with Science, which, some while ago, dropped (or disconnected itself from) the idea of 'God's Laws', which are the only possible answer to 'why'.
    It's quite amazing that people with religion and people without religion manage to co operate so well in Science without having to get heated with each other - whereas,in other areas of life, their ideas get in the way.
     
  19. Aug 19, 2013 #18

    rbj

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    i think that Zapper hit it more closely than the others. the OP did not ask "why does this fundamental force we call EM exist?" but why magnetism exists. i would interpret the question as "Given that the electrostatic force exists (for reasons we know not why), why is there this additional ostensible force acting on charged particles in motion (relative to other charged particles in motion)?"

    that's a legitimate "why" question and it does have an answer.

    that answer is that the effects we attribute to the magnetic field in classical physics are a manifestation of the electrostatic field while taking into consideration the effects of Special Relativity. put another way, if the speed of light was infinite, SR would have no effect on what we observe and magnetic forces would not exist.
     
  20. Aug 19, 2013 #19

    jtbell

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    What about the magnetic field that is associated with a time-varying electric field via the "displacement current" term that Maxwell added to Ampere's Law?
     
  21. Aug 20, 2013 #20

    rbj

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    how do you get that time-varying electric field?

    without moving some charge around?
     
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