Celestial objects in the very far future

[KingGambit]

Dear Physics forum,

Recently I read about iron star, the consequences of quantum tunneling.

And I wonder of these things.
Considering protons don't decay, and there's no big crunch and the universe expands normally (heck, I don't know what "normal" is) so there will be no big rip.

So in the far future (not far, far future ), objects with mass greater than red dwarf will be, either:
- Black hole (for really massive)
- Neutron star (certain mass)
- Black dwarf (lower mass)

And in the very far, far future, through quantum tunneling:
A. Would all black dwarves become iron star?
B. Would all neutron stars become black hole?
C. Would all neutron stars become iron star?
D. Can, say moon or earth mass object become iron star object?
E. Can, say moon or earth mass object become neutron object?
F. Will moon/earth mass object become black hole?

Thank you very much.

 

[Halc]

A. Would all black dwarves become iron star?
B. Would all neutron stars become black hole?
C. Would all neutron stars become iron star?
D. Can, say moon or earth mass object become iron star object?
E. Can, say moon or earth mass object become neutron object?
F. Will moon/earth mass object become black hole?

Don't like C since it is a change to a higher energy state. An iron star is less dense than a neutron star and thus has most matter in a higher (less low) energy state.
An iron object and iron star is the same thing, except the former might be in the shape of a wrench.

E is also false since they lack the mass necessary. The moon and Earth will fall into each other (and/or into the sun) long before this iron object state. All planets will spiral into their stars, and stars into other things. Orbits decay due to energy loss to gravitational waves and it seems this process occurs before the insane amount of time needed to reach the iron star stage. So I think the super long term fate of a typical object is to merge with some larger object before it self-morphs into this iron or black-hole state.

F. It was hypothesized that all objects in sufficient isolation will eventually become black holes through an unlikely chance process. So I've read in a similar article. I'm somewhat skeptical about this. Such a random process would create only a micro black hole which would have insufficient gravity to gather nearby material faster than it evaporates. I mean what exactly is going to form a black hole? A proton and neutron by chance get so insanely close that they become bound by gravity? I don't think so since neither are fundamental particles and are not sufficiently 'all in one place' to do that, and such a black hole seems to violate the naked singularity conditions. Maybe a significant amount of things by insane chance all happen to 'be' in that one place at once. I put 'be' in scare quotes because quantum things don't have a location until measured, but I suppose a black hole constitutes a measurment.

 

[KingGambit]

Thanks for the reply @Halc

E is also false since they lack the mass necessary. The moon and Earth will fall into each other (and/or into the sun) long before this iron object state. All planets will spiral into their stars...

But, I mean this.
If those objects were left alone on their own, given a very long, long time.
Will an earth mass object (or any object) quantum tunnel to iron?

 

[Halc]

If those objects were left alone on their own, given a very long, long time.
Will an earth mass object (or any object) quantum tunnel to iron?

If left alone for a super long time, yes, that's the lowest energy state at one scale. It's a gradual process, one atom at a time. I just protested the moon say every being left alone long enough for this to happen.

That and my skepticism about the spontaneous black-hole thing.

I remember the article saying that black holes all evaporate in the long term, so in the end there's nothing left but super-low level radiation and no objects anywhere.

 

[PeterDonis]

Recently I read about iron star, the consequences of quantum tunneling.

Where? Please give a specific reference.

 

[KingGambit]

Where? Please give a specific reference.

Sorry, not read, but watch

 

[PeterDonis]

Sorry, not read, but watch

Pop science videos are not valid references for a PF discussion. Do you have anything like an actual paper?

 

[TeethWhitener]

Do you have anything like an actual paper?

I don't know if OP does, but here's one from Dyson in Rev. Mod. Phys.:
https://www.panspermia.org/revmodphys.51.447.pdf

According to the wikipedia article on iron stars, it is claimed (without citation) that before the big bang theory was widely accepted in cosmology, iron stars were hypothesized to be very common. This makes sense; under steady state theory, the universe would be unimaginably old (possibly infinitely so), and the quantum tunneling processes required to transmute other elements into iron would easily be accommodated by such a long timescale.

 

[George Jones]

Not a published reference, but according to

https://math.ucr.edu/home/baez/end.html

"So what happens next?

Well, everybody loves to talk about how all matter eventually turns to iron thanks to quantum tunnelling, since iron is the nucleus with the least binding energy, but unlike the processes I've described so far, this one actually takes quite a while. For black dwarfs of masses between 1.35 and 1.16 solar masses, this will take between ##10^{1100}## years and ##10^{3200}## years, with the lightest ones taking the most time.

It's quite possible that proton decay or something else will happen long before this gets a chance to occur. But if it does, something exciting will happen! When a black dwarf with a mass over 1.2 times that of our Sun turns to iron, it will collapse under its own gravity, and explode into a supernova! These supernovae may be the last really energetic events in our Universe."

Check the references at the end of the article, including the published
https://arxiv.org/abs/2008.02296

 

[PeterDonis]

I don't know if OP does, but here's one from Dyson in Rev. Mod. Phys.:
https://www.panspermia.org/revmodphys.51.447.pdf

Note that in this reference, in the section on "all matter decays to iron", nothing is said about "quantum tunnelling". The rationale is simpler: "On the time scale (41), ordinary matter is radio-
active and is constantly generating nuclear energy." The time scale in question is ##10^{1500}## years. In other words, on that time scale, nuclei that we ordinarily consider "stable" are not, unless they are iron-56; any nucleus that is not iron-56 will undergo some nuclear reaction that moves it closer to being iron-56.

 

[TeethWhitener]

Note that in this reference, in the section on "all matter decays to iron", nothing is said about "quantum tunnelling".

No, but that section (section G) references the action integral from the prior section (section F), which is premised on quantum tunneling (or rather, "quantum-mechanical barrier penetration"). Nuclear (in)stability in general is premised on the notion that there is a large, classically insurmountable energy barrier between any given collection of non-iron nuclei and an equivalent collection of (lower energy) iron nuclei.

 

[PeterDonis]

quantum tunneling (or rather, "quantum-mechanical barrier penetration")

I think the latter is a better description in this particular case, because "quantum tunneling" gives the impression of a direct transition from, say, a lead-206 nucleus to an iron-56 nucleus, which of course does not happen. "Quantum barrier penetration" at least makes it clearer what's going on: the potential barrier around any nucleus has a finite height, so given enough time, something inside the nucleus will penetrate it and a nuclear reaction will take place. But the reactions in question are just the ordinary nuclear reactions like alpha decay, beta decay, gamma decay. Possibly some of them would be more esoteric, such as a "fission" type reaction involving a nucleus not normally considered fissionable. But there won't be anything like "lead quantum tunneling directly into iron".