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What is most fundamental, force or field?

  1. Jun 26, 2010 #1
    Are forces due to fields or are fields an abstraction of forces? Do electromagnetic waves exist apart from as an abstract description of changing fields, which are in turn abstract descriptions of changing forces (or potential of force if there was an object for force to be applied to)?
     
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  3. Jun 26, 2010 #2

    Andy Resnick

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    My understanding is that fields are more fundamental, as they have a physical existence apart from the objects that it interacts with. Forces, OTOH, only have operational meaning in terms of an interaction.

    For example, I teach that F = -qE (Coulomb's law) means that the force is something a charged particle would experience *if* it happened to be there. The field is there regardless.
     
  4. Jun 26, 2010 #3
    I would say a force is something that you can observe to be doing work or causing an attraction/repulsion in a field. The field always exists or you wouldnt be able to observe or feel the phenomena.
     
  5. Jun 26, 2010 #4
    I think F = -qE is just an equation. It doesn't show that the field is physically there. It could be that the field is just an abstraction of the fact that an object at that distance would experience a certain force. However, light, a propogating EM wave, seems to show that fields exist apart from particles (well, but then there's photons...).
     
  6. Jun 26, 2010 #5

    Andy Resnick

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    I think you misunderstood my point. How's this- there's no such thing as a force-meter (that is 'force' cannot be measured directly), but there are field sensors.
     
  7. Jun 27, 2010 #6
    Some physicist prefer to think of particles as excitations of quantum fields. In quantum field theory , 'force' is depicted as an exchange of particles. It's tempting to saythat fields are more fundamental.However, it's somewhat like the question 'which came first - a chicken or an egg?'.
     
  8. Jun 27, 2010 #7

    Vanadium 50

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    I think before this can be answered you have to answer a related question: given N quantities, how do you rank them in order of fundamental-ness?
     
  9. Jun 27, 2010 #8
    fields are not physical quantities, they have no dimensions themselves, you can measure the field strength not the field, like matter, you can measure mass and charge but not matter itself.

    forces however are physical quantities that have dimensions and measurable, so I think fields are the more fundamental entity, they have measurable properties, forces however are measurable themselves.

    my understanding to what would be more fundamental is what provides a more general/reductive description, we can generalize/reduce electric forces in the event of electric field-charge interaction for instance.
     
  10. Jun 27, 2010 #9
    I believe it makes sense to describe a force in terms of the behavior of objects/particles affected by it. I tend to say that objects "express" gravity by accelerating centripetally, for example. I don't know if it is possible to demonstrate the empirical existence of a field except as a pattern among various object behaving in similar ways. I was reading Einstein and he was discussing this issue with time and space, i.e. that there is no such thing as time outside of the movement of a given clock, except that multiple clocks can be observed simultaneously at different moments to give the same reading, which indicates a pattern of force consistency.
     
  11. Jun 29, 2010 #10
    Looks like nobody's listening.

    We should be on our guard to root out any form of fundamentalism, wherever and however it appears.:biggrin:

    At various points in history, this property or that concept have been held up as 'fundamental'.
    At one time, atoms were fundamental, before that it was earth, air, fire and water.
    It's all pure Tommyrot.

    One thing we ought to have learned is not to apply the language of absolutes to scientific questions - that sort of thing belongs in religion (so that people can properly go to war over it).
     
  12. Jun 29, 2010 #11
    I second AJ Bentley. Even if what we presently conceive of as fundamental fields actually are, asking which is most fundamental appears to me to imply the others are derivable from it. If that was so the other fields wouldn't be fundamental. It's like asking which [strike]came first[/strike] is more fundamental the chicken or the egg.
     
  13. Jun 29, 2010 #12
    The idea that absolutism is essential in language is itself an absolutist/fundamentalist notion. It is nothing more than an implicit assumption that a claim is taken as absolute instead of tentative. If one says, "matter is made of atoms, which form molecules," where is the absolutism? In the word "is?" Does one have to substitute "may be" for "is" in every claim to avoid formally avoid the possibility that the reader takes the claim to be absolute?

    Absolutism lies more in the implicit assumptions of readers than in the fundamental essence of a claim. If it is a habit of thought transmitted through language, it is done so not by the language itself but by the way ideas are framed and communicated. It's like a form of strawmanning when you make a statement and then someone else accuses you of it being an absolute claim without asking if that's what you meant.

    There's no such thing as involuntary authority-recognition. The only way an authoritative claim can be taken as absolute is if it is taken that way. If it is regarded as tentative it is tentative. Saying that it has to be explicated as tentative implies that absolutism is the default-setting of language, which itself would be a means of instituting absolutism.
     
  14. Jun 29, 2010 #13
    Absolutism is the default-setting of human existence!

    We get kicked out naked into a world of chaotic forces that we cannot hope to control or even understand, only to find that sooner or later those forces will inevitably snuff us out of existence.

    It's not hard to understand why the vast majority of us go completely insane by any logical measure of sanity and will grasp at any metaphysical straw in the hope of succour.

    Belief in absolutes is one of the larger straws.
     
  15. Jun 29, 2010 #14
    If it's a straw you have to grasp at, then it's hardly an absolute, is it?

    You also have no absolute proof that anything gets "inevitably snuffed out of existence." In fact, there is more evidence that nothing ever ceases to exist, unless you are counting form instead of substance.

    But what is ever absolute about form except insofar as it exists as a fixed abstraction in human consciousness? In reality, matter-energy are constantly interacting, resisting increases in entropy, etc. So even the resistance of form-change itself requires form-change.

    You can put as much faith in absolutism as you like but it won't change the reality that absolutism is an ideal that is never achieved in reality - except the reality of abstract consciousness.
     
  16. Jun 30, 2010 #15
    I'm not sure what brainstorm intended with the absolutism rant, but AJ made no claim that "absolutism is essential in language". Nor do I agree that conveyed absolutism is solely in the eye of the beholder. If I say something is actually fundamental I am saying it can be derived from something more fundamental. Whether others agree or not, my claim was absolute and I conveyed and intended it to be interpreted as such.

    Brainstorm didn't specifically say "absolutism is the default-setting of human existence", as AJ implied, he said that such a claim was an absolutist claim.

    Then AJ was being derisive of grasping at metaphysical straws, which brainstorm then turned it around to imply AJ was grasping at straws. Then throws a strawman argument using a burden of proof fallacy in asking proof that anything gets "inevitably snuffed out of existence", and throws in "absolute" proof to boot. If "absolute" is in the eye of the beholder, as previously claimed, I guess that's not really "absolute" so "absolute" proof is not needed. Give me "absolute" proof pterodactyl's still exist and I'll accept the premise that "absolute" proof is needed to support the contention that we are "inevitably snuffed out of existence". That was more than a grasp for a straw, that was the whole strawman.

    I think this ball has not only left the topic, it has left the park. The OP question was philosophical enough as it was.
     
  17. Jun 30, 2010 #16
    I think (hope) you mean 'can not be derived' ?
     
  18. Jun 30, 2010 #17
    My contention is that the idea of something being 'fundamental' in science is an obsolete concept.
    The OQ is not merely philosophical, it's akin to the question of 'angels dancing on a pin'.

    At every step taken over the last few centuries, we have found another layer beneath what we thought to be the bottom, or more correctly, we found a better, more succinct and sometimes more accurate way of stating the same thing.

    This is why we abandoned the idea of physical 'laws' for theories and hypotheses.

    My vote is to stop calling this or that 'fundamental' and just state only what we know to be true.
     
  19. Jun 30, 2010 #18
    Duh, yep, that's what I meant.

    I tend to agree with on the issue of calling something fundamental. As to whether anything truly fundamental exist, or anything we assume is actually is, is a philosophical question outside of science.
     
  20. Jun 30, 2010 #19
  21. Jun 30, 2010 #20
    Nice play-by-play summary, my_wan. Again, when you talk about "absolute proof" being "needed," you're implying that things can be absolutely denied in the absence of absolute proof, which would put a great deal of power on the side of denial/ignorance. Basically, what you're saying is that any pattern that has exceptions can be denied as a pattern because it's not an "absolute rule." However, since no rule lacks exceptions, no pattern could ever be acknowledged because it could never be established as absolute. You would lose all partial patterns by claiming absolutism as a criteria for claim-validation.

    It wasn't a strawman as much as I was using absolutism to deconstruct absolutism. As for the pterodactyls, you can only claim they are absolutely extinct if you establish that no pterodactyls evolved into subsequent species. Since species delineation and identification is a subjective art, you can only claim absolute extinction to the extent you can define the species and organisms as absolute.

    Depending on how you operationalize extinction vs. evolution, I think it would be difficult to say that some aspect of any organism or species doesn't continue to evolve in some way. If nothing else, a species is a part of an ecosystem that evolves by replacing certain species with others for various functions. If a particular bacteria in your digestive system became extinct as it was replaced with another, would you say your digestive system was absolutely altered? "Absolute" is relative to criteria, in other words - and criteria like other knowledge, can never be absolute in any essential sense.
     
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