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What all has intrinsic spin?

  1. Sep 1, 2015 #1

    jimgraber

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    Gold Member

    What does and does not have intrinsic spin?



    Wikipedia Spin (Physics)

    https://en.wikipedia.org/wiki/Spin_(physics [Broken])

    says:



    “In quantummechanicsand particlephysics, spinis an intrinsic form of angularmomentumcarried by elementaryparticles, composite particles (hadrons), and atomicnuclei.”


    But it doesn’t say that *only* those items have intrinsic spin.


    Is this list comprehensive? Or do other things have intrinsic spin? (as opposed to orbital angular momentum?) For example: molecules? Buckyballs?Ball Bearings? Schrodinger cats?


    Wikipedia Spin (Physics) goes on to say:

    “Spin is one of two types of angular momentum in quantum mechanics, the other being orbital angular momentum. Orbital angularmomentumoperatoris the quantum-mechanical counterpart to the classical notion of angular momentum: it arises when a particle executes a rotating or twisting trajectory (such as when an electron orbits a nucleus).[3][4]The existence of spin angular momentum is inferred from experiments, such as the SternGerlachexperiment, in which particles are observed to possess angular momentum that cannot be accounted for by orbital angular momentum alone.”


    Of course every large item has lots of electrons among other things and so it has spin due to the constituent electrons. I mean does the large object have any intrinsic spin of its own, beyond that inherited from its constituents.



    Arguing the other way is

    http://www.askamathematician.com/2011/10/q-what-is-spin-in-particle-physics-why-is-it-different-from-just-ordinary-rotation/

    In its derivation that every three dimensional object is either a fermion or a boson, where it states:


    “By the way, notice that at no point has mass been mentioned! This result applies to anything and everything. Particles, groups of particles, your mom, whatevs!”


    Is everything either a fermion or a boson?

    No matter how large?

    And thus perhaps possess its own intrinsic spin?

    Or does this only apply to total angular momentum and not intrinsic spin.

    I’m confused. Help!
     
    Last edited by a moderator: May 7, 2017
  2. jcsd
  3. Sep 1, 2015 #2

    mfb

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    2016 Award

    Staff: Mentor

    Everything. Sometimes the value is zero. For elementary particle, the Higgs boson is the only (known) example with spin zero. Many mesons have spin zero, and in general bosons that are composed of multiple elementary particles can have spin zero (or at least: there exists a related state with spin zero, even if it has a different name).
    Yes, as long as you can consider the system in isolation. For large objects that constantly interact with the environment that classification becomes meaningless. The intrinsic spin becomes negligible in that case as well.
     
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