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Higgs & Relativistic

  1. Dec 15, 2011 #1
    In another thread I asked the question if my mass is comprised of "Higgs Mass" and "Kinetic mass".

    Drakkith was nice enough to reply best he could, but wasn't certain.

    So yea, that's what Im wondering. Is my mass comprised of higgs and kinetic?
  2. jcsd
  3. Dec 15, 2011 #2


    The kinetic component is really easy to understand. Basically any energy that is confined looks like mass.

    Eg, say you had a box with a lot of light inside it bouncing off the walls, it would appear a little heavier. I believe it would be essentially indistinguishable from a little gas in the box, as regards its gravity, inertia and so on (I am assuming perfect reflection off the walls - perhaps a superconductor might achieve this?).

    Another type of confined energy is the kinetic energy of quarks bound by massless gluons in neutrons and protons, and as well as that all massive particles acquire what appears to be extra mass when they have some sort of other energy. For example, you are slightly heavier than if you were a lower temperature.

    What we consider mass depends on the resolution we look at really - you have a mass, the electrons and nuclei in you have a different total mass, the nucleons in the nuclei has masses that are a bit different to the nuclei themselves, and then the quarks in nucleons have masses that are way less than the nucleons they make. All the discrepancies are other sorts of energy (energy in bound particles being bound in general, I suppose).

    So the role of Higgs is to give the quarks and leptons a little mass in this picture.
    Last edited: Dec 15, 2011
  4. Dec 15, 2011 #3
    Ha, what's the ratio?

    (assuming it's only these two forms, only ones Im aware of)
  5. Dec 15, 2011 #4
    You could work it out. What you would need to do is work out how many up quarks, down quarks and electrons there are in your body (start from your mass, the fractions of each element, and how many neutrons and protons there are in the common isotopes)

    But the simple answer is that most of it is kinetic, simply because electrons are very light, and up and down quarks are a lot lighter than nucleons (look up their masses and those of neutrons and protons to see).

    It will seem a lot clearer if you do some of these calculations, I think. Well, except there is quite a lot of uncertainty about quark rest masses.

    [Note: remember a proton is two up quarks and a down quark. A neutron is two down quarks and an up quark]
    Last edited: Dec 15, 2011
  6. Dec 16, 2011 #5
    nitsuj, I am sure you have done this calculation now :smile:, but I will give a rough answer for comparison.

    Firstly, most of your mass is neutrons and protons. Each proton has an electron to go with it. If you added all these weights up it would be quite close to your total weight (binding between nuceons and in atoms and molecules cause corrections). I won't bother doing these corrections, as there are far bigger uncertainties later.

    Secondly there are about equal numbers of protons and neutrons in a human (again, given other uncertainties, I will not try to be more precise). So the numbers of electrons, neutrons and protons in a human are approximately equal.

    Masses of neutron and proton are 940 MeV and 938 MeV respectively.

    Mass of up and down quarks are 1.7-3.3 MeV and 4.1-5.8 MeV respectively. Note the large uncertainty.

    Mass of electron is about 0.5 MeV

    To get the answer with these assumptions, we need to compare mass(neutron + proton + electron) to mass(3 up quarks + 3 down quarks + electron)

    The first is 940+938+0.5, which is about 1879 MeV. The latter is about 18-28 MeV.

    Hence I infer that 1-1.6% of your mass is due to the Higgs mechanism, the rest is apparently due mainly to gluons. This is entirely different to the situation with atoms and the electromagnetic force - binding of nuclei and electrons leads to a small reduction in mass due to the binding energy caused by virtual photons.
    Last edited: Dec 16, 2011
  7. Dec 16, 2011 #6
    yea I laughed when suggested to calculate it.

    Thanks for sorting it out.

    So most of my mass is from the kinetic energy that gluons create? Do gluons hold the quarks together? Or is it what holds the proton and neutron together?
  8. Dec 16, 2011 #7
    Yes, it's gluons that hold quarks together to form neutrons and protons, but it's a lot more complex than the way photons hold electrons and nuclei together. In the later case, there are no photons with non-negative energy involved, so the net mass is less than the sum of the parts.

    I can't say I understand the details at all well, but there must be a lot of real gluons with positive energy inside each nucleon, and it is this that causes the rest mass of nucleons to be so high.
  9. Dec 16, 2011 #8
    Wow, that's bizzare, so many interesting points to consider with this stuff.
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