About the Gluon Field and Mass.

[JohnSSM]

I mostly wanted to verify this statement, made on this page...

 

http://www.physics.adelaide.edu.au/theory/staff/leinweber/VisualQCD/QCDvacuum/welcome.html

"the masses of the quarks illustrated in this diagram account for only 3% of the proton mass. The gluon field is responsible for the remaining 97% of the proton's mass and is the origin of mass in most everything around us".

Is this at odds with the Higgs theory of mass?

[ajb]

The Higgs gives mass to the fundamental particles, for composite particles the largest contribution to the mass is via the binding energy. I am unsure of the exact figures here, but for sure the sentiment of the statement you quote is correct.

[JohnSSM]

NIce...thanks for the confirmation...

But...

IF quarks are given mass by higgs, and the mass of the quarks is only 3 percent of a proton, why isn't the gluon field considered much more influential in gravity, when gravity seems to be popularly dictated by the higgs boson...

When we found the higgs "god particle" we were only finding what causes 3 percent of mass and gravitational influence? Doesn't binding energy seem more godly in this respect?

[ajb]

IF quarks are given mass by higgs, and the mass of the quarks is only 3 percent of a proton, why isn't the gluon field considered much more influential in gravity, when gravity seems to be popularly dictated by the higgs boson...

The classical gravity of macroscopic objects does not depend on the details of how this mass came to be.

 

When we found the higgs "god particle" we were only finding what causes 3 percent of mass and gravitational influence? Doesn't binding energy seem more godly in this respect?

Forget god, but yes. For astrophysics and cosmology (past early times anyway) the Higgs mechanism has little to do with most of the mass of composite particles and macroscopic bodies. The same is true for condensed matter physics.

 

Every physicist knows this, but science reporting in this context will most likely concentrate on the Higgs. The Higgs boson is still an important part of the standard model and so an important part of our understanding of the Universe.

[JohnSSM]

I just cant escape the obvious thoughts of the gluon field and gravity...

Can I ask if you know if the electromagnetic energy of objects adds to their mass? I know that' seems an off topic and wacky question, but if the energy of the strong force can add to mass, why couldn't other energies, like EM, also create the same effect?

[ajb]

I just cant escape the obvious thoughts of the gluon field and gravity...

The two are not directly related.

 

 

Can I ask if you know if the electromagnetic energy of objects adds to their mass? I know that' seems an off topic and wacky question, but if the energy of the strong force can add to mass, why couldn't other energies, like EM, also create the same effect?

The exact nature of the binding energy is unimportant; what is important is that you have a bound system.

[JohnSSM]

Another quick observation/question.

The gluon fields seems to be true vacuum energy...Where might that energy come from while in a vacuum? The literal source of that energy is?

As matter enters the field, it increases in activity and energy...where does the energy come from to increase that activity?

Can you honestly say that the gluon field is not related to gravity? IF the forces are ever unified, wont this be the reality of the situation? Every field and force would be connected....we just aren't there yet...but isn't that where we want to get?

[ajb]

The gluon fields seems to be true vacuum energy...

Why?

 

In any full calculation of the vacuum energy the gluons would contribute; assuming that this energy is due to virtual particles. Also be aware that there is a discrepancy of over 100 orders of magnitude between the measured upper bound on the vacuum energy and the theoretical calculations based of QFT.

 

 

Where might that energy come from while in a vacuum? The literal source of that energy is?

It is informally understood as being due to virtual particles. I don't think this is really well understood, see my comment above.

 

 

As matter enters the field, it increases in activity and energy...where does the energy come from to increase that activity?

What activity?

[JohnSSM]

As I read about the gluon field, it seems to be the only field that is quite active, even in a vacuum state, which I assume is simply "empty". I find it pretty interesting that the field that creates binding energy for many of the elementary particles is there even when the particles are not...but, as you add matter, compression or heat, the gluon field becomes more active...It must...It has all those newly introduced particles to keep bound together. But if the field isn't taking the energy to become more active, from the particles that exist within it, then where does the energy come from? It has to come from somewhere as energy is not created. This is to say, there is not EMF without EM...there is no gravity without mass/matter...Those fields seem to be driven by the energies of "magnets" and "masses". But the gluon field's energy levels seem to increase with demand. Is this any different than gravity increasing when we add more mass? Or the EMF field increasing in intensity as we add more charge?

Its really all those animations on the above referenced page that got me thinking about it. The field seems to be in a constant state of change.

If you are examining one very small sample chunk of space, and you could "image" the gluon field energy in real time, as those animations represent it, you would see a certain level of activity when no mass was within your sample. But as a truck drives through your sample, the gluon field would increase with activity as the truck passed through it. And when the truck left the sample space empty again, you would see the vacuum level of energy activity again.

IS this simply the perturbations of the gluon filed increasing as particles pass through it? It seems to represent a higher energy level. So I think, Where does that energy come from?

Looking at those animations may help you understand where Im coming from.

As for virtual particles, aren't they referring to an energized field with no perturbations? DO they basically create virtual particles to account for vacuum energies?

Once again, Im not at your level of discussion of the topic...

"Also be aware that there is a discrepancy of over 100 orders of magnitude between the measured upper bound on the vacuum energy and the theoretical calculations based of QFT."

When you say "the vacuum energy" what are you referring to? Is there anything that contributes to vacuum energy in empty space other than the gluon field?

And you're also saying that QFT does not solve the vacuum energy question at all. There must be speculation about this discrepancy and the cosmological constant being linked. Yes?

[MigL]

Every particle has an associated field. That's why its called quantum field theory.

Why you choose to single out the gluon field, I don't know.

Someday we may even find the particle associated with the gravitational field, the graviton.

 

Every particle can pop-up as a virtual particle/ant-particle pair, it just depends on the energy of the associated field.

Using your gluon field as an example, if you add energy to the system, by say, pulling two quarks apart, it is very easy to create two more quarks.

[ajb]

As for virtual particles, aren't they referring to an energized field with no perturbations? DO they basically create virtual particles to account for vacuum energies?

Simply put, the vacuum expectation value of the energy is not zero in most quantum field theories. This non-zero value is interpreted as being something to do with the virtual particles and the time-energy uncertainty relation.

 

You can get a picture of this by looking a the quantum mechanical harmonic oscillator. Indeed, free quantum field theories basically look like an infinite collection of harmonic oscillators. Anyway, you known that the ground state of a harmonic oscillator is non-zero.

 

 

When you say "the vacuum energy" what are you referring to?

The expectation value of the energy (for some given quantum field theory).

 

Interestingly, if you have a supersymmetric theory and the supersymemtry is not broken then you have exactly zero for the expectation value of the energy. (This maybe off topic a little, but it is a nice remark!)

 

 

Is there anything that contributes to vacuum energy in empty space other than the gluon field?

All fields will contribute to some extent.

 

You also can have contributions from fields that simply do not have zero VEVs. For example, this happens in the standard model with the Higgs mechanism.

 

And you're also saying that QFT does not solve the vacuum energy question at all. There must be speculation about this discrepancy and the cosmological constant being linked. Yes?

It is hoped that you really can understand the cosmological constant using QFT, but so far any calculations are wildly off. This is known as the vacuum catastrophe and is considered a big problem in physics.

[JohnSSM]

Well...darn it..its gonna be hard for me to understand this stuff with all these overlooked catastrophes in modern physics...

In the end though, Ill bet you that gluons and the strong force become very influential to gravity...shake on it? ten bucks!

[ajb]

In the end though, Ill bet you that gluons and the strong force become very influential to gravity...shake on it? ten bucks!

The typical energy scales of quantum theory and gravity are vastly different. There is no reason to expect that gluons have much directly to do with gravity; of course as they carry energy-momentum they do couple to gravity, but the gravitational force between gluons etc is tiny. The situation is less clear near the scale of quantum gravity, which is probabily near the Planck scale. However, we just don't have great models at that kind of scale and so who knows.

 

Now something you maybe interested in is using techniques from the strong force for gravity calculations. The so-called MHV amplitude that were originally developed for gluon scatterings were realised by Witten to have a geometric interpretation via twistor string theory. These methods have been applied to gravitational amplitudes. So in this sense yes, the strong force and gravity are related, but formally.