If a star 3 to 4 times as massive as our Sun collapses, a Black Hole forms.
The general consensus is that the gravity becomes so strong the mass concentrates to an infinitely dense zero dimensional geometric point.
This creates infinities and infinitesimals that doesn’t play nice with computations in General Relativity and Quantum mechanics.
(for now, I’m setting aside alternate constructs like Gravastars Gravastar - Wikipedia )
What if…instead of a geometric point with no size…the singularity is a lump of what I propose to be called “Planckium”…matter compressd into fundamental, elementary units of Planck Density:
one Planck Volume with one Planck Mass. Planck units - Wikipedia
These units…although tiny, are finite.
Have scientists already proposed this as a solution?
You appear to be proposing some kind of naive thesis of a quantized construction of a black hole. However, this would require a working theory of quantum gravity which has thus far eluded physicists for over eighty years for a number of different reasons. In order to advance this as an actual hypothesis you’d have to construct some alternative formulation which is functionally equivalent to the the Kerr metric (to start with) which satisfies the Einstein field equations for a black hole.
It should be noted that “Planck Density” is not a fundamental unit but is derived from a combination of the Planck mass divided by units of the Planck length. It isn’t clear that Planck units actually represent a fundamental limitation of the properties of spacetime, and in fact there is a whole subarea of research into the “Trans-Planckian problem” of phenomena that occur beyond the Planck scale.
Are you using “naive” with the common usage of not comprehending the complexities or mathematically as in naive set theory that uses natural language and is not axiomatic? I read it as the second.
In the second sense, as a theory that does not have explicitly stated assumptions or a rigorous formulation. It wasn’t intended to be a pejorative criticism, just that the notion as stated doesn’t have a clear way to formulate or test it.
This would be something that we’d get out of a theory, not something that we’d use as an input for a theory. It is widely suspected that, in a working theory of quantum gravity, one prediction would be that black hole cores are finite (but very small) objects rather than true singularities, but since we don’t have a working theory of quantum gravity, nobody knows for sure, and I don’t think anyone would be particularly surprised if it didn’t work out that way, either.
This isn’t the general consensus. The general consensus is that general relativity as formulated (namely, entirely classically) is not able to tell us what happens at the center of a black hole.
It would be unsurprising if, in some eventual resolution of the question, relevant expressions are simplified by invoking Planck units, but that’s about as far as such basic reasoning can go.
The issue is, basically: what is it that keeps it from collapsing further? There must be some kind of force, whether one produced by a force carrier, or a pseudoforce, or something entropic in nature, or something else… but general relativity doesn’t allow forces over a certain magnitude. We know why neutron stars and white dwarfs stop collapsing at a certain point (but will collapse further if you add mass). But the same isn’t true of this hypothetical non-singularity. However small it is, general relativity requires that it get smaller yet.
If general relativity is incorrect at these small scales, then that could be an explanation. But then you need some theory for why it holds at large scales but not small (i.e., quantum gravity). And no one has managed that yet.
Since what happens past the Event Horizon is unavailable to us with our present understanding of physics, I realize the interior could be anything from a point to a volume equal to or just smaller than the Event Horizon…or any size in between.
The classic “Black Hole” has a “structure” proposed by Schwarzchild…commonly accepted by the scientific community.
The afore mentioned Gravastar proposed and formulated by Mazur and Mottola as an alternative to the black hole.
Both are solutions according to General Relativity and operate the same way “outside” the event horizon.
It simply occurred to me that a construct based on the Planck Scale as a metric could place an ultimate limit of “smallness” using known physics.
Before Max Planck formulated the quantum…h or h-bar…scientists assumed energy was emitted or absorbed on a continuum.
If energy can be reduced to discrete “chuncks” like photons, maybe density can, too.
Sure, but that’s all just handwaving. There’s a lot more to quantum mechanics than just “Hey, what if energy emission wasn’t a continuum?”. There’s a whole detailed theory behind that, with all sorts of structure to that not-a-continuum, that took a lot of experimentation, math, and deep thought to develop. That theory is, so far, lacking, for anything that would predict a non-singularity in a black hole.
It is important to keep the bulk spacetime structure separate from the singularity itself. There is general consensus that spacetime is not likely to behave super weird inside the event horizon. After all, I can’t today see what is happening tomorrow or two light years away, but today I feel pretty confident about how physics works tomorrow or two light years away. The event horizon is a boundary not terribly different from these, so no one expects pink elephants inside the event horizon.
But the singularity at the center is a separate issue entirely, and the only consensus about physics at (or very near) the singularity is that our current theories aren’t up to the task.
What you are proposing is that something quantum-y happens to save our sanity at the singularity. This is a fine elevator pitch for “Maybe someone ought to figure this quantum gravity thing out, eh?”
It should be noted that the solution for the Einstein field equations for a hypothetical non-rotating black hole treat the the singularity as a point, any real-world singularity would be expected to have some amount of angular momentum (because any collection of more than two real masses drawn together by gravity will have some net torque component), and thus the ergosphere and inner singularity will not be symmetric in all three orthogonal directions. The Kerr metric, which is a solution for a non-charged, rotating black hole (basically, the simplest possible real world solution) has a gradient profile of an oblate spheroid and an inner singularity that is disc-shaped.
From a practical standpoint, once an object (or information) passes through the event horizon it effectively disappears from our universe because no light or information can pass back through that horizon. From within the event horizon (for a sufficiently gentle gravitational gradient such that the object is not torn to component atoms) there is no such significance for the internal observer, and they only way they can tell that there is a boundary is because any attempt to go outward results in just falling inward faster.