First Measurement of Distribution of Pressure Inside a Proton (phys.org)

Okian Warrior shares a report from Phys.Org: Inside every proton in every atom in the universe is a pressure cooker environment that surpasses the atom-crushing heart of a neutron star. That's according to the first measurement of a mechanical property of subatomic particles, the pressure distribution inside the proton, which was carried out by scientists at the Department of Energy's Thomas Jefferson National Accelerator Facility. The nuclear physicists found that the proton's building blocks, the quarks, are subjected to a pressure of 100 decillion Pascal (1035) near the center of a proton, which is about 10 times greater than the pressure in the heart of a neutron star. The result was recently published in the journal Nature.

Comments

Is there energy to be had here?

[MichaelSmith]

Is Subnuclear fission a possibility?

Re:Is there energy to be had here?

[LordHighExecutioner]

If there is, it will be taxed.

Re:Is there energy to be had here?

[Zorpheus]

Only if quarks could exist in a state of lower energy than inside a proton. I don't think such a state exists, so the answer is no.
What is possible is matter-antimatter annihilation. So if we found a cheap source of antiprotons ...

Re:Is there energy to be had here?

[pezezin]

Maybe. Some physicists have proposed the existence of "electroweak stars", where energy would be generated from a process know as "electroweak burning" where quarks are converted to leptons: https://en.wikipedia.org/wiki/...

Re:Is there energy to be had here?

[Anonymous Coward]

Nuclear fission is possible because there can exist free residual nuclei which in sum hold less energy than starting large fissile nucleus. It is a sort of balanced equation of materials and energy, where on both sides of equation you have all materials accounted for, but in terms of energy, you get surplus free energy on resulting side.

In case of nucleons however, we don't have such equation, because as far as we know, in nature's supply, we only have protons and neutrons, and they are approximately same size. If quarks could exist in free form, or build some stable particles smaller than protons and neutrons, we'd could have a theoretical chance to rob protons or neutrons of a part of their energy.

Re:Is there energy to be had here?

[lgw]

Is Subnuclear fission a possibility?

Well, the proton is already the lowest energy level. The binding energy for hadrons works a bit differently than for atoms - pulling a quark out of a photon requires so much energy that new quarks are created and the quarks remain bound in particles. Free neutrons, OTOH, decay with a half life of ~14 minutes IIRC, when they aren't packed in tightly with other protons and neutrons.

TFS is a bit odd too. Of course the pressure in a proton is greater than in a neutron star - when the internal pressure in a start exceeds the pressure inside a neutron, the neutrons collapse and you get a black hole. And protons and neutrons are reasonably similar.

Re:Is there energy to be had here?

[Anonymous Coward]

So if we found a cheap source of antiprotons ...

Start an Internet campaign that protons are racists. You'll have more antiprotons than you know what to do with.

Re:Is there energy to be had here?

[kiminator]

I'm assuming by this term you mean a fission process which occurs within protons or neutrons, rather than within atomic nuclei. The answer to that is no, no matter how you slice it.

A short explanation for this is simply that quarks are stable particles, like electrons. It's not possible for there to be lower-mass versions of the up/down quarks which we haven't yet observed. There are certainly higher-energy versions of these same particles, but quarks themselves cannot exist except when bound to one another, either in mesons (two quarks) or baryons (three quarks, like protons and neutrons).

The reason why quarks can't exist alone is that if you take a meson and try to pull apart the two quarks that make it up, it takes so much energy that a quark/anti-quark pair is created, so instead of pulling a meson apart to get two quarks, you end up with two mesons. Similar things happen if you try to pull a quark out of a baryon (like a proton): you end up with a baryon and a meson instead of a meson and a free quark.

In the end, the proton is the lowest-energy stable state that a collection of three quarks can wind up in (mesons are all unstable, and rapidly decay into either electrons/positrons and neutrinos if they have charge, photons if they do not). But higher-mass baryons, of which there are a great many, will decay into other baryons and collections of particles. This process of more massive baryons decaying into protons/neutrons is probably the closest thing to "subnuclear fission" that exists.

Re:Is there energy to be had here?

[BitterOak]

The problem is that you would need to convert a quark to an antiquark, which is a bit tricky.

You can't turn quarks into anti-quarks, and this is directly related to the conservation of baryon number. Protons and neutrons have baryon number 1 each, while mesons have baryon number 0, and as far as we can tell, baryon number is a strictly conserved quantity. Since protons and neutrons are the lightest baryons, the "sub-nuclear" fission described is, as far as we know, not possible under the laws of physics as we understand them.

1035?

[johannesg]

1035 doesn't sound so bad. 10^35 on the other hand...

Jefferson Lab Open Day May 19th

[OzPeter]

If you are in the Newport News, VA area on Saturday, the Jefferson Lab is having an open day from 9AM to 3PM. https://www.jlab.org/

Also the press release from the lab itself about the Proton pressure QUARKS FEEL THE PRESSURE IN THE PROTON

Macroscopic concept?

[Anonymous Coward]

Could someone please explain this? I always thought pressure was a more macroscopic concept, related to the force exerted by (many) bouncing particles on a wall, or similar. What is the meaning of pressure within a proton? And what is its meaning? Like density or "edges", I would think macroscopic concepts are no longer valid in that realm.

Re:Macroscopic concept?

[CustomSolvers2]

pressure was a more macroscopic concept

Pressure is force per unit of area and is relevant in any context where an area exists. No matter how small quarks are, they are 3D objects and forces applied on them can be modelled via pressure.

Like density or "edges"

Same than before: size doesn't matter for any of this. See the proton as an sphere and the elements inside it having certain distribution.

Re:How much teen angst is that?

[maroberts]

And where is there a safe space for those poor quarks?

(Also, BeauHD, you shmuck: It's 10^35, or write 10e35, not 1035).

I'm sure Quarks will be safe on DS9

Color force

[Okian Warrior]

In thought strong force refers to the force that binds the protons inside the necleus.... Do quarks even need a force holding them together? Like does opposite spin quarks repel each other?

The color force holds three quarks together in a proton or neutron. Protons have charge, so there's significant repulsive force among them inside the nucleus.

A quark inside a proton can be bound (by color) to the two other quarks in that proton, but it's also physically near the quarks of a neighboring proton. It can "look outside" it's own particle and see other nearby quarks, and feel the color force from those as well. That's what we call the strong force, and it keeps the nucleus together.

If heavy nucleii were composed completely of protons, the aggregate electromagnetic repulsion would overwhelm the strong force and the nucleus would fly apart. Adding a few neutrons to the mix allows the same sort of neighboring-color-attraction without the EM repulsion, and makes the nucleus stable.