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I was thinking about energy scale, measured in eV and i've found this graph. Now, roughly speaking, if we think energy as a mass, we can measure it in $eV$s. Then from the graph we have for example electron is lighter than proton, which is lighter than Higgs, and so on.

But, what if we think about it in terms of length? Electron is smaller than proton, and that's ok. So this means that Higgs should be bigger than proton.

And so, why this image is putting atom (100 eV) before electron (0.5 Mev), for example?

Thank you

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    $\begingroup$ if we think energy as a mass, we can measure it by eV An eV is a unit of energy, not mass. $\endgroup$
    – G. Smith
    Commented Apr 7, 2020 at 18:21

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Don't mix up the unit systems. The image shows energies in the natural unit system, where the speed of light is set to unity, $c=1$. The posted image shows "atoms" around $100eV$, which to my believe is wrong. Most probably it tries to indicate the atomic transitions, which are on the order of $10eV$ -- e.g. check out the ionisation energy of hydrogen, which is $13.6eV$.

So, the image is an energy scale. You are not allowed to swap energy by length and assume that an atom is smaller than an electron. It's just wrong.

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  • $\begingroup$ Well, i think your point of view is correct. I was not considering it $\endgroup$
    – Fed_EnAyEm
    Commented Apr 8, 2020 at 9:20
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The image you post shows the rest mass energy of the systems it depicts,(if you ignore the four leftmost lines which confuse the issue*). This has no relation to size in space.

But, what if we think about it in lenght term? Electron is smaller than proton,

yes, because an electron is a point elementary particle whereas a proton is a composite of valence quarks, a gluon and quark antiquark sea. Nuclei are even more composite and larger because of that.

So this means that higgs should be bigger than proton.

No, the higgs is an elementary point particle too, as all the particles seen in the table.

So length and energy are two different independent variables, which depend on the system studied, and might be correlated, nuclei get bigger the more protons and neutrons they have,but it is not a one to one correlation.

___* you have not given a link or the description of the table. As it is , the four leftmost lines are inconsistent,photons, gravitons have zero mass. neutrinos are close to zero, but the lines for molecules an atoms are on a different scale, if you realize that molecules are systems nuclei.

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  • $\begingroup$ Ok, now i understand. But if we consider electron and higgs which are both point particle, how can i think the fact that they have very different mass? Since they are point particle i can't define some sort of density.. $\endgroup$
    – Fed_EnAyEm
    Commented Apr 8, 2020 at 9:18
  • $\begingroup$ That is why quantum mechanics was invented. At the moment the point particle hypothesis works beautifully in fitting an enormous amount of data with quantum mechanical theories $\endgroup$
    – anna v
    Commented Apr 8, 2020 at 9:31

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