Could Black holes forge heavier elements that have yet to be discovered?

  • Observations




    • The heaviest elements known in abundance in nature are forged deep within stars.


    • These elements are made possible by the high densities/pressures within the stars.


    • Black holes are known to have a much higher density/pressure than any known star.


    • Black holes are also known to be a phase of stellar evolution - this suggests that the original star's internal process of forging metals would persist within the resultant black hole.


    • Scientists have forged synthetic/ephemeral heavy metals under conditions which could hypothetically be sustained within a black hole.




    Hypothesis:



    Black holes forge heavier elements that have not been observed on earth. The conditions needed to sustain these elements are unique to the black hole, due to its high density/pressures. These conditions can be glimpsed, but not sustained in any experimental context



    Follow up questions:




    • Has this been hypothesized?


    • Where can I find research on this topic?



    I think you probably want to look into neutron stars, rather than black holes. The core of a neutron star *is* (very loosely speaking) a nucleus of a very heavy element. Like all sufficiently heavy elements, it would normally fly apart in a moment, but is held together by its own gravity and the mass of the crust of the neutron star piled on top of it. Concepts like density, temperature and pressure make sense for a neutron star, but not really for a black hole. I suggest you do dome reading (eg on wikipedia) on these subjects and come back with a more refined question.

    If they did then we wouldn't know.

    If, as suggested in your self-answer, you have in mind primordial black holes, then please edit your question to make this clear. Otherwise people are wasting their time explaining to you about solar-mass and heavier black holes.

    I fear you have fallen into the trap of "All A are B, therefore if some A cause C, all A must cause C" , which is of course not true.

    Carl - thanks for the feedback, however its not immediately clear what A and C are in your analogy. As a consequence, it cannot be ascertained what leads you to believe it is suggested that "All A must cause C".

    @Ben Crowell Thanks for the feedback - but I respectfully disagree with you. I don't think others would be wasting their time. Rather they would be contributing to our collective understanding. Bear in mind, this was my first question posted on the Astronomy Stack exchange. This question has value - and has sparked some interesting conversations. Please consider taking a more community-oriented approach. Strive to encourage others, and hold yourself to a higher ethical standard.


  • The heaviest elements known in nature are forged deep within stars.




    No, the heaviest elements are made on Earth in scientific laboratories, or in the extreme gravity of a neutron star's crust.




    These elements are made possible by the high densities/temperature/pressures within the stars.




    Many of the larger elements can be made in supernovae and neutron star collisions, not in stars. It requires extreme conditions for these elements to form.




    Black holes are known to have a much higher density/temperature/pressure than any known star.




    Black holes are actually very cold, they "absorb" any radiation that passes their event horizon. Outside the event horizon may be some very hot material, but it is not actually so hot compared to the core of a star.




    Black holes are also known to be a phase of stellar evolution - this suggests that the original star's internal process of forging metals would persist within the resultant black hole.




    No, inside the black hole everything falls, and reaches a singularity in a short amount of time.




    Scientists have forged synthetic/ephemeral heavy metals under conditions which could hypothetically be sustained within a black hole.




    As above, the conditions beyond the event horizon are unlike anything we have on Earth, because there is the unavoidable singularity.



    After some matter has crossed the event horizon it will certainly come to the singularity. (in the same way as you will certainly reach tomorrow) And as it gets closer the tidal effects get greater, eventually ripping the atoms apart. The extreme gravity in a black hole will tend to pull matter apart not fusing it to larger atoms.



    There may be nucleosynthesis in the accretion disc around a black hole. While the amount of high mass atoms made here is relatively small, it may be useful for the sake of detecting and distinguishing black holes from neutron stars or white dwarfs.


    Also may be worth pointing out we don't know what happens at a singularity because they're all inside black holes we can't see into. (We can predict, but our predictions are based on models that weren't designed with any data from singularities)

    Almost a complete answer ;-) but it's worth commenting on the OP's premise that "Black holes are known to have a much higher density/pressure than any known star". A supermassive BH may have a lower density than water.

    I never understood the idea that stars can only make atoms up to iron. Shouldn't there be some chance of producing higher-weight atoms too? Quantum uncertainty and thermodynamics and all that...

    @Mehrdad But why... It certainly CAN happen, but it will not last. Ice doesn't spontaneously appear in a boiling kettle even if it CAN. Iron is the element where you gain no energy from fusion, nor from fission. It is the final destination for any nucleosynthetic equilibrium. Only in non-equilibria processes will you find elements heavier than iron (i.e: violent explosions, or specifically designed particle jets...)

    @StianYttervik: This isn't like ice in a boiling kettle is it? I imagine there are bound to be some atoms moving fast enough to fuse into something heavier than iron. And once that happens, the result doesn't necessarily need to decay anymore, so it will last. Am I missing something?

    @mehrdad if the atoms were moving fast enough to fuse, the resultant atom is also moving fast enough to undergo fission. Not that "moving fast enough" is the proper description, but using your words for comprehension

    @Stian: I can't say I understand your logic. It sounds like you completely ignore statistics? Just because two atoms might occasionally be moving fast enough to give that doesn't mean there is a 100% chance of a third atom breaking up the product again.

    @StianYttervik Elements heavier than iron **are** formed inside stars (known since the **1950s**). The reason that they don't form by fusion is that at the temperatures required to tunnel through the Coulomb barrier they are also vulnerable to photo-disintegration. Not fission.

    @Robjeffries good point. There are processes that are at an equilibrium, you need irreversible conditions to progress past iron. Better?

    @StianYttervik you need to read about the s-process. No problem to attach neutrons to nuclei.

    Maybe we should say, "and your constituent particles will reach tomorrow."

  • Superheavy elements have short half lives because of their extreme instability with respect to alpha decay and fission. This is a result of their high electric charge, which results in strong forces of electrical repulsion. Although theorists have predicted an "island of stability" due to quantum mechanical shell effects, this stability is a relative thing. We're still talking about half-lives on the order of seconds or less. So any such element created by astrophysical processes will not survive for very long, even if it doesn't fall into the black hole.



    So conceivably in the accretion disk, outside the event horizon, you could get some fusion events resulting in the formation of superheavy elements, but those elements would not survive for very long, even if they were somehow ejected rather than infalling past the horizon. And the normal methods for detecting and characterizing superheavy elements would not work here. Normally we look for things like alpha-decay chains with characteristic alpha energies. Those would not be detectable from outside the accretion disk, since charged particles interact strongly with matter and are stopped.




    The conditions needed to sustain these elements are unique to the black hole, due to its high density/pressures.




    Most of the interior of a black hole (inside the event horizon) is probably an extremely good vacuum. The only high densities and pressures would be near the singularity. So any exotic matter formed at high densities and pressures would not be observable from earth or have any consequences for the outside universe, because nothing can escape from inside the event horizon.



    If we were to send a space probe inside a black hole to look for exotic matter being formed near the singularity, the probe would not be able to report its results back. Also, the region of high-density and high-pressure infalling matter would exist near the singularity, which would probably not be detectable to the probe until the probe itself had been destroyed by the same processes. (On the inside of a black hole, if general relativity is correct, you can't see the singularity. You only see infalling photons from the outside.)



    If exotic matter is formed near the singularity, it will only exist for a very short time before accreting onto the singularity. (IIRC the maximum infall time for a 10-solar-mass black hole is on the order of milliseconds from horizon to singularity.) We don't really know what happens at the singularity, but we certainly can't have atomic nuclei under those conditions.


    milliseconds from which frame of reference?

    @Michael: Milliseconds of proper time, i.e., the time on a clock that is infalling along this trajectory. The proper time for free fall from horizon to singularity for a Schwarzschild black hole is equal to the Schwarzschild radius over $c$, multiplied by a unitless constant of order unity. (The exact value of the unitless constant depends on the state of motion as you pass the event horizon. Starting from rest at the horizon is only possible in the sense of a limit.)

  • The problem of the superheavy elements is not that we can't forge them. Their problem is that they decay very quickly. For example, Oganesson, the heaviest element synthetised until now, has a half life of 181 ms.



    In theory, even much heavier elements could be created in particle accelerators, but there is no way to even detect them.



    In neutron stars, or in exploding supernovas, all the elements are created, but there is no way to even detect them. We can consider a neutron star as a large nucleus with $\approx 10^{56}$ neutrons.1



    In black holes, the fact is that no one knows, what is in them. They don't radiate anything (with a very little exception), and nothing leaves the singularity in them. To understand what is in them, would require currently unrealistic advances in Physics. The singularity in their center is probably not baryonic matter, though, thus we could hardly say that it would be any chemical element.



    1As @PM2Ring's excellent comment says, neutron stars also have a significant number of other particles, too, not only neutrons. I also extend it that they are bound gravitationally and not by the strong interaction, which makes them in this aspect essentially different from nuclei.


    Thanks for your perspective - there is a small misinterpretation which I should clarify better. I didn't suggest that we have a problem in forging the heavier metals. I hypothesized that black holes forge heavier elements, which have not been observed yet. I also suggested that the internal processes of the black hole might be best informed by that of its preceding star, namely the process of forging heavy metals. I then asked if this has already been hypothesized, and for references to any existing research.

    @efreezy Ok, but 1) no one knows, what the singularity of the BHs do. The current theories estimate some "string soap" in them, with $10^{19}$ bigger energies than a single proton. Most likely there is nothing in them which creates any baryonic matter. 2) BHs are mainly static entities, at least viewing them out of the event horizon. They don't synthetize anything, not heavy elements, nothing. Colliding black holes give gravitational waves, and there is a nearly-accepted theory that they give also a negligible amount of hawking radiation (it is in the order of $10^{-40}$ Watt).

    @efreezy Well, and the infalling matter in the accretion disk generates also a lot of photons, mainly gamma rays, some heavy element synthesis can happen in them, it is true, but the created heavy nuclei are very few and they decay very quickly, just in the Earth particle accelerators.

    @efreezy If you are looking for the largest amount of heavy element producers of the Universe, you might find close white dwar - red giant binaries. There the WD sucks the outer athmosphere of the red giant, and above a limit, it becomes a supernova and collapses into a neutron star or black hole. In this supernova explosion, a large amount of free neutron matter might be ejected from the stellar core, which decays very quickly to a soap of all elements of the periodic system. But this ejection and then decay happens so quickly that what we can see in telescopes, only a clear signature of

    @efreezy the large-mass decay of strongly radioactive heavy elements - embedded into the usual spectrum of a supernova explosion. A comparison: in a supernova explosion, the main part of the core collapse happens in seconds. Oganesson decays in 0.2 seconds.

    Thanks Peter for looking into this and offering those conceptual additions. I have summarized the result of my question and your feedback into a concise answer in the answer section below.

    I think you mean "soup", not "soap". FWIW, a neutron star isn't pure neutrons. They are hypothesized to have a layered structure, with an outer crust consisting of relatively normal heavy atoms that transitions into a mixture of such nucleons and neutronium, pure neutronium, and possibly some exotic quark matter in the core. However, even pure neutronium is *not* solely composed of neutrons. It's a dynamic substance that also contains some protons (and electrons) with the concentration of protons ranging from around 10% to 1%, depending on pressure.

    @PM2Ring Thanks the grammar fixups, unfortunately I can't edit my comments any more. :-( Thanks also the important extensions.

    Virtually every sentence of this answer contains mistakes. *The problem of the superheavy elements is not that we can't forge them. Their problem is that they decay very quickly.* No, the problem is that we can't forge them. We lack appropriate beam-target combinations, and the cross-sections are extremely small. *For example, Oganesson, the heaviest element synthetised until now, has a half life of 181 ms.* This would be some isotope of that element. The half-life is a property of the isotope, not the element.

    *In theory, even much heavier elements could be created in particle accelerators, but there is no way to even detect them.* Not true. Superheavy elements are often extremely easy to detect once formed. Typically the recoiling nuclei are allowed to fly out of the target to a detector, which detects alpha decays. *In black holes, the fact is that no one knows, what is in them.* I guess this depends on what you mean by "know." We certainly have theories that can predict this. However, the region inside the event horizon is causally disconnected from the outside universe.

    *nothing leaves the singularity in them.* What is more relevant is that nothing gets out past the event horizon. *The singularity in their center is probably not from baryonic matter, tough, thus we could hardly say for that it would be any chemical element.* No, the singularity is expected to have almost all of its mass originating from baryonic matter.

    @BenCrowell Virtually every sentence in this post is a simplification, because the question statement has made clear that the OP wants an answer to his question, and not a book written by me on the spot. Virtually every sentence in your critic is true by fact, and false by interpreting these non-essential simplifications as essential mistakes. Yes, all what you say is true - and all what you say picks a non-essential part in the answer. If you think that yes, the OP needs a long essay, explaining everything on his appearent level of knowledge, then I suggest to write that long essay and post

    @BenCrowell Well, that is essential mis-interpretation from your side: *" No, the singularity is expected to have almost all of its mass originating from baryonic matter."* <- The question is not about, what the matter of the singularity is originated, the question is about that "does it forge heavy elements" (formulation by the OP).

    You say in your comment "WD sucks the outer athmosphere of the red giant, and above a limit, it becomes a supernova and collapses into a neutron star or black hole". This is inaccurate: type Ia SNE don't create such remnants; the explosion completely disrupts the star.

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Content dated before 7/24/2021 11:53 AM