Where EXACTLY is the Mass of an Atom? Proton? Quark? Hadron? Gluon?

  1. Where EXACTLY is the "Mass" of an Atom? Proton? Quark? Hadron? Gluon??

    Just look at the simplest Hydrogen atom -- one Proton. The question is *where* exactly is the mass of this thing? Or *what* makes up the mass of this thing? Is it just Quarks? So where is the *mass* of those things? Where is the difference between mass and energy. Is there any? Is there really such a thing as mass, or is it all just energy appearing in different forms? Does anyone know? Is this the end of Physics and the beginning of Philosophy, again meaning no one really knows???

    No one seems to have made this clear on Wikipedia either...
    http://en.wikipedia.org/wiki/Mass
    http://en.wikipedia.org/wiki/Quark#Mass

    In a hadron most of the mass comes from the gluons that bind the constituent quarks together, rather than from the individual quarks; the mass of the quarks is almost negligible compared to the mass derived from the gluons' energy.​

    Really? Mass comes from gluon energy? If so is there really such a thing as mass, or is there only energy? Why do we think a rock has "mass"? Is a rock really a bunch of energy, but at our scale we perceive it as this so-called "mass" stuff?
     
    Last edited: Jan 13, 2009
  2. jcsd
  3. DavidSnider

    DavidSnider 505
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    Last edited: Jan 13, 2009
  4. Re: Where EXACTLY is the "Mass" of an Atom? Proton? Quark? Hadron? Gluon??

    Right, I get that. But if you hold a rock in your hand (apparently a bunch of matter), and you look closer and closer at it, where is the actual "matter" and where is the "energy"?
     
  5. DavidSnider

    DavidSnider 505
    Gold Member

    Re: Where EXACTLY is the "Mass" of an Atom? Proton? Quark? Hadron? Gluon??

    Matter is a form of energy. It's kind of like asking where the water in an ice cube is.
     
  6. Re: Where EXACTLY is the "Mass" of an Atom? Proton? Quark? Hadron? Gluon??

    Well I guess the question is -- is there any such thing as matter at all, or is there ONLY energy? What is the distinction? When you look closely into a proton, where is the "matter", or is there no such thing, there is only energy that just appears to be matter but only at a certain scale?
     
  7. malawi_glenn

    malawi_glenn 4,726
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    Re: Where EXACTLY is the "Mass" of an Atom? Proton? Quark? Hadron? Gluon??

    We had that discussion in several other threads this week regarding "mass - energy"

    I mean we can always go further down in scale, til we encounter strings or whatever is the building block for the gluons and quarks.

    But speaking in terms of standard model, the mass of hydrogen is proton + electron - bidning energy (13.6eV). The mass of the proton is mass of valence quarks + quark/gluon sea (the binding energy of the proton, which is positive in this case)
     
  8. Vanadium 50

    Vanadium 50 18,038
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    Re: Where EXACTLY is the "Mass" of an Atom? Proton? Quark? Hadron? Gluon??

    I think it's a mistake to try and say the energy (or mass) is in one place. Energy (and mass) is a property of configurations of objects.

    Consider two photons flying away from each other. Neither has mass. But the system does.
     
  9. malawi_glenn

    malawi_glenn 4,726
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    Re: Where EXACTLY is the "Mass" of an Atom? Proton? Quark? Hadron? Gluon??

    One can ask what makes up the mass, but not "where is the mass located"
     
  10. Re: Where EXACTLY is the "Mass" of an Atom? Proton? Quark? Hadron? Gluon??

    The answer to this requires years of physics studies:

    Things get more heavy in different reference frames, mass defect, mass hyperboloid, inertial or gravitational mass... First you should probably know what mass you are referring to.

    Then we have the problem that "where" doesn't work anymore in quantum mechanics, if you have any information about the speed/the energy.

    Then we can dissolve massive particles into electromagnetic energy and back, which happens like mad in the calculations for tiny time differences.

    But for most purposes we just say the atom has mass and that's it.
    On the next level we say the proton and the electrons have mass but these objects don't exist in a place anymore, but they just appear there when we measure. The proton can be broken down further, but it changes its apearence depending on the speed of our probe.

    "The everything is energy approach" which many "new age"y people seem to fantasize, fails pretty badly for electrons, which have 0 size, so no known substructure and carry a mass.
     
  11. Re: Where EXACTLY is the "Mass" of an Atom? Proton? Quark? Hadron? Gluon??

    That is a bit simplistic, so I would like to specify that energy distributions still exist in the quantum world.
    Talking about the proton mass, the strong interaction is more relevant than the electromagnetic one, which is a small (albeit important) correction.
    I think it would be more appropriate to talk about scale dependence. In particular, the concept of "speed" (as a spatial derivative) is not very well suited to virtual particle. At best, let's talk about momentum transfer.
     
  12. Re: Where EXACTLY is the "Mass" of an Atom? Proton? Quark? Hadron? Gluon??

    I think the distinction occurs when talking about inertia.

    A photon does not have inertia, but does have mass. And so energy on its own does not have inertia.
     
  13. Re: Where EXACTLY is the "Mass" of an Atom? Proton? Quark? Hadron? Gluon??

    How do I measure the mass of a photon ?
    What would be an instance of "energy on its own" ? Where can I find that ?
     
  14. Re: Where EXACTLY is the "Mass" of an Atom? Proton? Quark? Hadron? Gluon??

    I should have been more clear, what I meant was: A photon has a gravitational pull, but no inertia. So they are not exactly the same thing. The way you could measure it is by watching how much light bends when it passes large stars. And then treat it as a particle and find the mass that it would have if it was a particle.

    And what I meant by that was just because something has energy, it does not necessarily have "mass" (as in the kind of mass that has inertia).
     
  15. Re: Where EXACTLY is the "Mass" of an Atom? Proton? Quark? Hadron? Gluon??

    I thought photons always use the straightest spacetime trajectories (geodesics).
    Do you mean, applying Newton's formulae and deducting the equivalent mass ?
     
  16. Re: Where EXACTLY is the "Mass" of an Atom? Proton? Quark? Hadron? Gluon??

    Yeah, and that means that they follow a curved path in our 3 dimensional world. And always curve towards massive objects. I think, but I am not sure at all, that the higher the frequency of an photon (and the higher energy) the more gravitational attraction it has and so the higher frequency photons curve round things more.


    Yes

    btw; I am not an expert on this.

    [edit] Can someone confirm if I am right or not please, I don't want incorrect things to be in this thread[edit]
     
    Last edited: Jan 15, 2009
  17. Re: Where EXACTLY is the "Mass" of an Atom? Proton? Quark? Hadron? Gluon??

    "All of the above" would be an accurate answer.

    As for where these basic constituents derive their masses, well, we believe it's through interaction with the Higgs field. LHC experiments in the coming years will (hopefully) shed some light on that issue.
     
  18. Re: Where EXACTLY is the "Mass" of an Atom? Proton? Quark? Hadron? Gluon??

    So mass is the result of an interaction? With a field? The interaction of what with a field? And is an "interaction" another way of saying "energy", or not? And you mean we have to do more experiments because we really don't know? Is all of this to say that we really don't know what-the-heck mass actually is? How very strange!
     
  19. Re: Where EXACTLY is the "Mass" of an Atom? Proton? Quark? Hadron? Gluon??


    It is kind of strange. Truth is, it's still basically a mystery where the masses of fundamental particles come from. So far, they are just input parameters for the Standard Model.
     
  20. Re: Where EXACTLY is the "Mass" of an Atom? Proton? Quark? Hadron? Gluon??

    Why ? I personally find quite impressive that we have even the perspective to answer such a question !
     
  21. Re: Where EXACTLY is the "Mass" of an Atom? Proton? Quark? Hadron? Gluon??


    There just seems to be such a huge and obvious disconnect! Drop a rock on your foot = ouch! Whack a rock upside your head = really ouch! That thing has mass! It seems so obvious.

    But apparently it is not. Where is the mass in that rock? Well, y'know, it just obviously, like, has mass, or something. You can, like, just see it and do experiments and see the results of this "mass" stuff. Right?

    But probably the majority of a rock is the vacuum of space -- so that can't be it, right? Do the electrons swirling around the nucleus have mass? "Electrons have no known substructure and are believed to be point particles" -- that just sounds ridiculous! http://en.wikipedia.org/wiki/Electron Yet they supposedly "have mass" or something. And as you dig into Protons you never actually find that "stuff", that "mass" that makes up the rock, do you? You find more charges, or interactions, or energy, or bonds, or some cool cutting-edge, poorly-understood, we'll-get-that-someday-in-the-future theoretical thingamajobbie -- but nothing that has any apparent "substance" -- whatever that might mean!

    When a rock whacks you upside the head, where/what is the mass?
     
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