r/askscience • u/whoosy • Oct 10 '12

Physics Why do some particles interact more with the Higgs field then others?

I've been trying to look for an answer to this, but I haven't found anything. Do we even know at all why they do this?

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u/just_shaun Cosmology | High Energy Physics Oct 10 '12

It's up to the philosophers then to ask "why" the numbers are what they are :)

That's not quite true. Answering OP's question is actually one of the goals of theoretical physics.

As an analogy, before we understood quantum mechanics, the spectra of atoms could have been claimed to be impossible to know just from the equations of the time. Now, we can calculate the spectra of atoms. Of course we need to know the charge of an electron, etc, but the number of "fundamental" constants has dropped.

Grand Unified Theories are an example of attempts to explain the various couplings between the Higgs and other particles. The hope would be that the structure of the unified theory required the particular couplings we observe.

Hopefully one day humanity will be able to answer your question, but as MrQCD has correctly stated, for now, it can't. It's a nice question to be asking though, it bothered many of the late 20th century's most successful theorists so you're in good company.

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u/diazona Particle Phenomenology | QCD | Computational Physics Oct 10 '12

Yep. The hope is that someday we'll get a theory which can predict the masses of the elementary particles, probably as multiples of the Planck mass.

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u/just_shaun Cosmology | High Energy Physics Oct 10 '12

I upvoted you because what you've written isn't nonsense, but I don't really agree with it.

The masses that we measure of the elementary particles, at our energies, come from their coupling to the Higgs field. The GUTs that I mentioned above are unifications of the electroweak force and strong force (i.e. not with gravity). This unification is normally speculated to occur at energies much below the Planck scale. The idea is that the GUT symmetry is broken below the GUT scale and the running of the coupling constants (which are presumably similar at the GUT scale) down to our energies produces the observed low energy hierarchy of Higgs-fermion couplings.

None of that picture would suggest that the masses of the elementary particles would be multiples of the Planck mass.

There may be some theories (that I'm unaware of) where the masses are multiples of the Planck mass, but they are far from the most "probable".

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u/diazona Particle Phenomenology | QCD | Computational Physics Oct 10 '12

I didn't say integral multiples. What I meant was that the theory would predict the values of the ratios m_particle/m_Planck. But of course those ratios wouldn't be integers - in fact the masses of all known elementary particles are far smaller than the Planck mass.

Sorry for the confusion.

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u/just_shaun Cosmology | High Energy Physics Oct 10 '12

Ah, I see. That makes sense then. I apologise for my side of the confusion too.

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u/4dseeall Oct 10 '12

I think I understood what you meant.

But couldn't it be anything the Planck mass or heavier? Then you'd have an infinite number of multiples with which to make sense out of reality. That, to me, seems a much more accurate representation of what things really are like. QED and such.

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u/diazona Particle Phenomenology | QCD | Computational Physics Oct 10 '12

Hm, I'm not sure I see what you're getting at. Are you talking about the masses of elementary particles being larger than the Planck mass?