# B Proton "pressure"

#### Sanborn Chase

Gold Member
I recently read the proton has an outward force of 10e35 Pascals with an equal inward force containing it. Can this be true?

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#### mfb

Mentor

1035 Pa * (radius of proton)3 = 400 MeV or roughly half the proton rest energy. If you want to define a "pressure of a proton", whatever that might mean, it has to be in that range.

#### Sanborn Chase

Gold Member
I'm fairly certain it was Phys.org. From whence cometh this "opposing pressure" to the proton's outward force?

#### cmb

I'm an engineer I would not put myself forward as a particle physicist. However, it is the common currency of physics that pressure is the energy of any field per unit volume; J/m^3 (and as a J = N/m so it is the same as N/m^2).

Whenever there is a non-zero 'field' then the field will have an energy and you can define a 'pressure' for it. Whether that means the same thing to you as, for example, a pressure of a gas in (or on) a sealed bottle might not be the same conceptual idea, but whichever way you approach it, pressure is energy per unit volume.

There is an energy field that holds protons and neutrons together; the strong nuclear force. The gluon is the mediating particle of the strong nuclear force proton field.

#### Sanborn Chase

Gold Member
Thanks for your response. I am a dilettante. Gluons sound fine to me, but the descriptions of them I've read don't seem to jive with the use of the Pascal as unit measure. Using that term I'm getting approx. 240x10E25 total area outward force on a "point" four nanometers in diameter. To have that EXACTLY balanced as in the current model is a stretch for me. Isn't the strong nuclear force a description of the binding force holding the nucleus together? Does it apply equally to the components of the nucleus? Don't we need a mediating force?

#### mfb

Mentor
Four nanometers is not a scale you'll see anywhere in connection with the strong interaction.
To have that EXACTLY balanced as in the current model is a stretch for me.
There is nothing that would need fine tuning to be balanced.
Isn't the strong nuclear force a description of the binding force holding the nucleus together? Does it apply equally to the components of the nucleus?
It is, and to a good approximation it acts the same on all quarks in a nucleus.
Don't we need a mediating force?
Mediating between what?

#### cmb

Four nanometers is not a scale you'll see anywhere in connection with the strong interaction. There is nothing that would need fine tuning to be balanced.It is, and to a good approximation it acts the same on all quarks in a nucleus.Mediating between what?
Well, I was going on the content of wikipedia [https://en.wikipedia.org/wiki/Strong_interaction] which says the force holding the quarks together is the strong nuclear force, which is mediated by gluons.

"The strong interaction is observable at two ranges and mediated by two force carriers. On a larger scale (about 1 to 3 fm), it is the force (carried by mesons) that binds protons and neutrons (nucleons) together to form the nucleus of an atom. On the smaller scale (less than about 0.8 fm, the radius of a nucleon), it is the force (carried by gluons) that holds quarks together to form protons, neutrons, and other hadron particles. "

Every quantum field has mediating particles as force carriers, does it not?

#### mfb

Mentor
Well, I was going on the content of wikipedia [https://en.wikipedia.org/wiki/Strong_interaction] which says the force holding the quarks together is the strong nuclear force, which is mediated by gluons.
That is correct but I don't see the connection to your previous question about "a mediating force". The strong interaction is mediated by gluons. Gluons are not a force, they are force carriers (similar to the photon).
Every quantum field has mediating particles as force carriers, does it not?
Every interaction ("force") has.

#### cmb

Sorry, typo, I meant mediating particle.

"Proton "pressure""

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