Would Heat Death overcome Strong Nuclear Force?

[Gerinski]

Hi, layman here.

As I understand, the theoretical Heat Death of the universe would imply that the accelerating space expansion reaches an expansion rate so big that it takes bodies and eventually even fundamental particles apart, leaving them alone up to an ultimate point in which no particle could ever interact with any other since they would all be receding from each other at a rate faster than the speed of light. The universe would be dead for all practical purposes, since no interactions could happen anymore.

My question is about such a Heat Death effect on Hadrons. Also according to my layman understanding, the strong nuclear force gets stronger with distance increase, explaining why hadrons can not be split into their constituent quarks.

So my question is, would the Heat Death imply that even hadrons would eventually be stripped down into their constituent quarks, or would hadrons remain bound together up to the theoretical Heat Death final destiny?

From the assertion that the strong nuclear force gets stronger with distance increase, it might seem that as space expands the strong force binding the hadrons would get stronger and stronger preventing them from ever becoming split into the constituent quarks?

Thanks !

 

[Chalnoth]

This model is the big rip, not heat death. The big rip is highly speculative and unlikely: it requires that dark energy grows over time, and there's a number of reasons to believe that it can't. But yes, in the big rip model even protons would eventually be pulled apart.

The more likely model is that dark energy is made up of a cosmological constant. In that model, everything that is not gravitationally bound together will eventually be outside our cosmological horizon. This means that the collection of galaxies known as the Local Group will be the only objects which we will be able to communicate with eventually. The Local Group will remain relatively stable, and heat death will progress as the entropy of our universe gradually increases. For some more details as to what happens in this situation, this Wikipedia page is an excellent reference:
https://en.wikipedia.org/wiki/Future_of_an_expanding_universe

 

[maline]

The Local Group will remain relatively stable, and heat death will progress as the entropy of our universe gradually increases.

According to that Wikipedia article, most matter will eventually be ejected from the galaxies. If I understand correctly, these objects will then eventually be spacelike separated from anything else. However dense objects such as planets or dead stars will not "fall apart" in the same way, because these ejections depend on high-speed exchange of momentum. If protons do not decay, the atoms will fuse into iron and form perfectly ellipsoidal, cold, fully magnetized iron balls that will last forever in isolation, except those that fall into a black hole before all the black holes evaporate. If protons do decay, what is left will be elementary particles (electrons, positrons, and neutrinos), and these will indeed end up spacelike separated from one another.
Either way, you are correct that the expansion should not generate free quarks.

 

[Chalnoth]

According to that Wikipedia article, most matter will eventually be ejected from the galaxies. If I understand correctly, these objects will then eventually be spacelike separated from anything else. However dense objects such as planets or dead stars will not "fall apart" in the same way, because these ejections depend on high-speed exchange of momentum. If protons do not decay, the atoms will fuse into iron and form perfectly ellipsoidal, cold, fully magnetized iron balls that will last forever in isolation, except those that fall into a black hole before all the black holes evaporate. If protons do decay, what is left will be elementary particles (electrons, positrons, and neutrinos), and these will indeed end up spacelike separated from one another.
Either way, you are correct that the expansion should not generate free quarks.

Yeah, that's why I said "relatively". These processes take ridiculous amounts of time to occur. In particular, stars being either ejected from galaxies or falling into black holes takes roughly a hundred million times longer than it will take for galaxies that we aren't gravitationally bound to to disappear (which will take a couple trillion years, or over a hundred times the current age of our universe).

 

[maline]

Yeah, that's why I said "relatively". These processes take ridiculous amounts of time to occur. In particular, stars being either ejected from galaxies or falling into black holes takes roughly a hundred million times longer than it will take for galaxies that we aren't gravitationally bound to to disappear (which will take a couple trillion years, or over a hundred times the current age of our universe).

Good point. But I- and I'm guessing, the OP- am more curious about "The End". What structures in our universe can last literally forever? If protons do not decay, the OP seems correct that the quark bonding can. Galaxies, on the other hand, cannot.

 

[Chalnoth]

Quark bonding can only sort of be broken in an extremely high-energy environment (a quark-gluon plasma). In lower energy environments, whenever you try to separate quarks, mesons are produced instead of free quarks.

In the context of protons, this would be a form of proton decay.

 

[maline]

In lower energy environments, whenever you try to separate quarks, mesons are produced instead of free quarks.

In the context of protons, this would be a form of proton decay.

If I understand correctly, trying to separate quarks from a hadron generally give you unstable mesons, plus a hadron like the original.

 

[Chalnoth]

If I understand correctly, trying to separate quarks from a hadron generally give you unstable mesons, plus a hadron like the original.

It really depends. In practice, you can produce any number of mesons or baryons as long as they observe various conservation laws. But the principle is the same: separate quarks too much, and they produce quark/anti-quark pairs between them, so that you can never actually have a lone quark wandering around. All you have are hadrons (mesons + baryons, including their anti-particles).

 

[maline]

It really depends. In practice, you can produce any number of mesons or baryons as long as they observe various conservation laws. But the principle is the same: separate quarks too much, and they produce quark/anti-quark pairs between them, so that you can never actually have a lone quark wandering around. All you have are hadrons (mesons + baryons, including their anti-particles).

Right, I'm just saying you probably won't get rid of your original proton that way.

 

[Gerinski]

Thanks a lot guys, so, if I understand well, even in such an extreme future scenario, we might arrive to a situation in which extreme spacetime expansion might overcome the gravitational and electromagnetic attraction between particles so taking them apart from each other forever, but that expansion would never strip a hadron down to its component quarks, the ultimate remaining particles in such a dead universe would be loose hadrons and leptons, having lost any possible causal connection among them, neither gravitational nor by electroweak interaction, but they would remain bound by their strong interaction.

 

[maline]

extreme spacetime expansion might overcome the gravitational and electromagnetic attraction between particles so taking them apart from each other forever

All the expansion does is add distance between things that are not bound. The bound structures that we have will mostly fall apart in the long run because of random interactions, not by being "pushed apart" by expansion.

the ultimate remaining particles in such a dead universe would be loose hadrons and leptons

Not exactly. As above, if hadrons (protons) in fact never decay, then they will remain bound in nuclei, forming eternal atoms. Within large bodies, these will be iron atoms- the most stable nuclei. These will be organized in macroscopic metallic crystal structures.

 

[newjerseyrunner]

It depends on whether protons are stable or not. Heat death means that entropy has increased to the maximum, not that everything has decomposed. We've never observed a proton decaying and have no mathematical proof that it does.

 

[Chalnoth]

We've never observed a proton decaying and have no mathematical proof that it does.

This isn't true. The fact that we have a matter/anti-matter imbalance in the present universe indicates that there exists a process that goes from a state where baryon number is zero to a state where baryon number is non-zero. By CPT symmetry*, this process must be invertible with some non-zero frequency, which would result in proton decay.

* Matter/anti-matter asymmetry implies CP symmetry violation, but it is generally expected that CPT symmetry is an exact symmetry of nature that is not violated (as CPT symmetry violation implies Lorentz violation).