This is the third in the series on Black Holes (or more accurately, Dark Holes, as true Black Holes cannot exist in our universe). The first essay explains how the black hole can't form because its progression in time comes to a standstill as the escape velocity at its surface approaches the speed of light. The second essay describes how the so-called black holes act as cosmic recyclers by winding up the infalling starlight such that over the life of the black hole it is constantly spewing out hydrogen and likely other low atomic weight atoms and nuclei (not to mention electrons).
In this essay I consider what happens at the end of a black hole's life.
I recall reading an old book by Fred Hoyle. I think it might have been Frontiers Of Astronomy. It was a book in my dad's library. I recall imagery of concentric circles representing the interior of stars. The central theme is that the denser, higher atomic number elements sink to the core of the star (pushing the lighter, less dense low atomic number elements out of the way) and so there are various regions where different fusion activity is going on.
Early on in the life of a star it is all about hydrogen fusing to helium and dueterium. As this is going on, energy is being released. See, the mass of the star is pulling on itself, trying to fall inwards. But this can't occur without the particles of matter ramming into each other more and more and generating heat, which counteracts the tendency for the matter to continue falling in. But still radiation energy will escape on the surface of the matter no matter what, and this energy is lost to the star. So all the while the matter is compacting inwards as it gets more and more dense.
As it's getting smaller and denser, the surface area of the mass is decreasing relative to its mass. That means there is less and less surface area for the star to lose energy through radiation. So this slows down the energy loss. But at all stages there is an equilibrium, as heat is released from the infalling matter slamming into itself the temperature is rising, and as it rises more radiation is able to escape through the surface, permitting the matter to continue contracting more.
The temperature inside just keeps going up and up. But finally the temperature is high enough such that the particles of matter (say hydrogen) start slamming into each other with enough energy to overcome their mutual repulsion (due to their like charges). Recall that like charges repel, unlike charges attract. That means two protons push each other away, as do two electrons, but an electron and a proton attract each other. Now in hydrogen's case when a proton (the nucleus of a hydrogen atom, or hydrogen without the electron) fuses with another proton, you get deuterium. One of the protons becomes a neutron. This has more mass (and energy) than either of the original protons, but it has lessmass (and energy) than both protons together. That energy isn't lost, it is just released as part of the fusion event. You get (I think) a neutrino and some gamma ray. Regardless of details, some energy is released. So when you fuse two protons you get a dueterium nucleus and some extra energy, which ends up just making the nearby matter hotter.
SO! Once the temperature rises enough due to gravitational collapse, fusion starts and energy is released. This energy release is enough to prevent further gravitational collapse. The temperature goes up some, and that causes the matter to spread out more, and density is lower, and surface area increases, and more heat energy in the form of radiation (light) is able to escape. And just as before at all times an equilibrium is reached. In both cases, there is a situation of negative feedback.
In the first case the energy liberated as the matter settles into itself ends up as heat, which counteracts the continued infalling. In the second case the energy increase due to increasing density is stopped by the energy release of the fusion activity. Still in both cases the energy makes its way to the star's surface and escapes as radiation, or light, of a broad range of wavelengths.
So two protons become deuterium, and then what? Other types of fusion occur also. Deuterium and a proton can become tritium. Tritium and a proton can become a helium nucleus. Two helium nuclei combine to create... what? Boron? Something. Whatever. The point is that when these small nuclei combine, they move up the periodic table into higher atomic number elements, as well as a variety of isotopes of the elements. Rrecall that isotopes have the same number of protons, just a different number of neutrons, compared to other atoms of the same atomic number. The atomic number is a measure of the number of protons in the nucleus, and that is the single most important value that determines the nature of that atom. Vary the neutrons and there are differences (some isotopes are unstable and will fly apart upon occasion, to be specific). Also heavier isotopes don't diffuse as fast as the lighter versions, just by nature of their greater inertia.
Anyway Hoyle's book showed these concentric circles. See, he explains that inside the star you have lighter elements on the outside fusing to create heavier elements further in (downwards). So inside the same star you will have a variety of fusion activity going on. Deeper in you have heavier elements fusing to form still heavier ones. So these shells form and the atoms migrate more or less to where they're comfortable based on their density compared to all the others. These shells keep forming, as long as there is fuel to burn, which as far as we know is mostly hydrogen.
But the hydrogen eventually runs out. So the outer shell will stop producing higher elements. So the next shell in which is fusing those higher elements to still higher ones, also runs out. This continues to occur until everything is fused to...what? A solid block of matter, a single atomic nucleus with atomic number on the order of 10 raised to the 50th power? Well, sort of. That's a neutron star, and there seems to be evidence they do exist.
But prior to that something happens. The whole negative feedback mechanism works because fusing the lighter elements into heavier ones releases energy. But something happens when you get to iron. For some reason I'm unsure of (but which I'm sure the Standard Model can readily explain), iron is the end of the line. Fusion still continues on, producing atoms with higher numbers than iron, but what's different is that now energy is consumed. That means in order to fuse nuclei into elements beyond iron costs energy. You don't get energy out.
That is the reason why we can take heavy elements like plutonium or Uranium (specifically U235) and cause them to split (fission) and energy is released. It's because to form them in the first place required energy to be put in. But when that becomes the primary form of fission in the core of the star, meaning elements are forming that are beyond iron, the negative feedback phase ends and we enter a positive feedback phase. Recall that when energy is released by fusion, the star gets hotter, and this causes the star to expand -- thus preventing further gravitational collapse. But when fusing consumes energy there is no mechanism left to prevent the collapse of the matter. As gravitational energy is released in the form of heat, it is consumed to fuse heavier and heavier elements (beyond iron) and the star's collapse just keeps on going.
Now finally I can get to my point about Hoyle's book. As I recall he says this collapse is actually halted, provided the star isn't too massive, by the formation of a neutron star. See, a neutron star is just a masssive ball of packed neutrons, one giant atomic nucleus. Normal matter in theory can't get any denser than that. So (according to Hoyle) the infalling matter triggers the creation of a giant neutron crystal, extremely dense and necessarily a whole hell of a lot of gravitational energy has to be released somewhere. As I recall Hoyle's claim was that the infalling matter impacts upon the growing neutron star and bounces off it, causing a shock wave that passes back up through the lesser and lesser dense regions of the star. Hoyle compares it to the cracking of a whip. Or it seems to me the same as when an ocean wave runs aground and stands up and crashes over itself. Hoyle's point is this is the underlying mechanism for the Supernova explosion.
He says it's because the mass falling inward at the end of a star's life, when the bulk of fusion is producing beyond-iron elements, slams into the neutron star core and the rebound produces a whip-like effect, and this blows off the outer shell of the star. Hoyle claims so much energy is released so quickly that this creates what we perceive as a supernova. Those objects last for around a year until they pretty much dim out to invisibility, but during their life the can outshine the entire galaxy they're residing in. They can occur at any time, any where, unexpectedly. Some are nearby and can be so bright they are bright enough to read by, like a full moon. But they'll be points of light. I don't think anyone alive today has seen such a nearby supernova. But they have been witnissed a few times in the last 500 or 1000 years, people wrote about them.
Anyway here's my point. I never liked Hoyle's whip explanation. I'm not sure I'm remembering everything correctly. It might not have even been a book by Hoyle. But I think it was. We're talking like 40 years ago. I don't have the book and I'm not even sure my father still does. Regardless, the whip analogy was proposed and was in favor for some time (might still be). But I've never liked it. Recently I was thinking about it again, and it dawned on me what I don't like about it.
See the cracking of a whip is a very brief event. What's going on is the whip is not of uniform thickness. It gets thinner as you get closer to the end (the end you don't hold on to). You hold onto the thick part. You contrive to swing the whip and you impart energy, in the form of a wave, that moves down the length of the whip. But something cool happens. Energy must always be conserved. So you introduced a wave at the end where the whip was most thick, you've pumped a lot of energy into the system. As the wave moves down the length of the whip the whip is getting thinner and thinner. The energy must be conserved! It can't just vanish. The only way to conserve it is if the wave progresses faster and faster. Finally the wave is so fast and violent that it swings the small end of the whip so quickly that it is travelling faster than the speed of sound. And you get a sonic boom. And that's the crack of the whip.
Inherently this whole event is brief. Yet a supernova lasts on the order of years. It makes no reasonable sense to me that all the matter bouncing off the neutron star core would just conveniently impact all at the same time and so give rise to a perfect, uniform, all encompasing pulse that covers the entire surface of the star. What about the star's rotation? How does that fit into everything? Angular momentum must always be conserved. There is always some net rotation in any big accumulation of matter. As it compacts due to gravity, the rate of rotation must constantly be increasing in order to preserve angular momentum. By the time we've gotten down to that tiny, dense ball surrounding the neutron star core, it's going to be going pretty damned quick. The rotational speed might even be getting appreciably close to the speed of light. But it is almost unthinkable that there is no rotation at all, so all the matter can just nicely and uniformly fall down on top of the perfectly spherical neutron star core and rebound, all at exactly the same instant and thus give rise to the whip-like effect...
Poppycock. Morover, there is another reason why I can't buy into it. Recall that in the core of the star, as matter is constantly fusing into heavier and heavier elements, draining gravitational energy away, forming the neutron star crunchy center... particle by particle is slamming into the neutron star. Each new particle sticks. And in the process the gravitational energy must be released as heat. It's gravity that's causing the compaction in the first place. As the density goes up, energy is released. Every snick! of a new particle becoming a part of the neutron star releases energy, probably neutrinos and gamma rays. Heat. Aha! Energy is released, which is the negative feedback we need to slow everything down.
There is no magical mechanism that can cause all the matter to combine into the neutron star core all at once, or practically so. Rather, as in the other cases, at all times an equilibrium is reached. As matter is forced into the neutron star core crystal, energy is released which keeps the temperature high, causing the outside matter to expand, slowing down the collapse. So the neutron star forms bit by bit, not all in an instant.
So what are we left with? I claim the whip-like explanation for the supernova is just too magically unlikely. And I claim any requirement that the gravitational energy is released practically instantaneously during the formation of the neutron star is also ridiculous. Let me go more into why the fast release of energy is important.
If you dig into the history of the fusion bomb, say by reading Richard Rhodes book Dark Sun: The Making Of The Hydrogen Bomb, you will come across photos of the fireballs produced when the bombs were detonated. The fusion bomb is kind of cool in that if you want a bigger explosion, all you need to do is add more hydrogen (or tritium or deuterium) fuel. The fusion of the fuel is triggered by the detonation of a fission bomb, which itself is triggered by the runaway chain reaction of fissioning radioactive material, occuring in the briefest time achievable. Once the hydrogen isotope fuel starts to blow, it's all going to blow. And in an instant it all fuses to higher order atoms and a huge amount of energy is released. Huge, for us. We're tiny, after all. On the scale of the sun fusion is going on all the time and our little fusion bombs are insignificant on the sun's scale.
Now my point in bringing up the fusion bomb and the fireball it produces is, the scientists conducting their experiments needed a way to determine the yield of each bomb. They worked out that if you measure the diameter of the fireball that you get you can pretty accurately gauge how many kilotons of TNT equivalent energy was just released. I recall one of the bombs, I think it was Castle Bravo, ended up releasing 2 to 3 times as much energy as was predicted. That must have scared the hell out of everyone. Anyway my point is about the size of the fireball.
What is the fireball? Well it occurs to me that when the hydrogen bomb goes off it produces so much energy in such high density that the temperature must get up into the millions of degrees. That's really high. So you've got a hell of a lot of really powerful radiation expanding outward at the speed of light. Both very dense, and very energetic (narrow wavelengths). And you've also got a lot of matter moving outward very, very quickly. This energy release keeps expanding and slamming into more matter (the atmosphere) and heating it up, but itself is cooling down. Very quickly the temperature drops as the mass of heated matter increases. So what was in the millions of degrees for a relatively tiny mass (the bomb material itself) eventually must drop to the thousands of degrees for what... probably millions of tons of atmosphere. The fireball we see and recognize as an indication of how much energy was released is the final point where the crazy expansion stops, where we've pretty much got a nice smooth temperature gradient from the core to the outside, and with heat flow when you have a smooth gradient the flow slows down and down...
My point is, intuitively, it is clear a larger fireball means more energy was released. The fireball stops expanding, and how big it got tells you how much energy it had. I haven't dug into the math. But it's no stretch of the imagination that the math involved is manageable and that it's all been pretty well worked out.
Getting back to the supernova, I compare the hydrogen bomb fireball with the supernova itself. One thing about the hydrogen bomb fireball is that you have this big ball of white and red-hot matter and it's right there in your face, blocking out a big angle. Like being close to a roaring fire. You'll be getting a lot of heat thrown at you. I bet that Castle Bravo shot drove everyone into the shadows, just because of how hot it must have been to be blasted by the heat from such a large fireball. That's what's going on with the supernova. You get 10's or 100's of millions of typical star energy release for a short time. That only makes sense if some mechanism is releasing that energy very, very quickly. It's a fireball, but on a stellar scale. The temperature might be into the 100's of millions of degrees or even billions, but across something the size of the sun. That energy has to dissipate. So it spreads out, and cools down, and if it's travelling at the speed of light (a reasonable assumption) after a year it will be a hot ball of gas two light years across (because it's spreading out in all directions). That's pretty big compared to a typical star. They're on the order of millions of miles across (our sun is a million miles in diameter). A light year is around 9 million times bigger than the sun. So there you have it! You've got 5000 to 10000 degree temperatures emitted from a volume way, way bigger than the sun. Since radiation energy goes up linearly with surface area, and surface area goes up as the square of radius, if we're talking about a radius 18 million times bigger than the sun that amounts to 324 trillion times as much surface area. Ok, so we're a bit off, on the high side.
Supernovae are on the order of 10's or 100's of millions of times brighter than a typical star. So maybe the hot mass expanding outward isn't quite so close to the speed of light, and maybe it's not quite so hot after a year... after all supernovae only last around a year, then they're almost invisible compared to their maximum. The key requirement is, somehow a huge amount of energy must be released in a very short amount of time. The rest falls into place.
But I've rejected the standard explanations of what is causing this brief release of energy. So what does cause the required release of energy?
Yep, the final disintigration of the black hole. Or dark hole as I prefer. Here's what's going on.
The matter falling inward doesn't bounce off the expanding neutron star and blow the outer part of the star off to form the supernova. Rather, the matter falling inward always maintains equilibrium and gradually the neutron star gets bigger and bigger. But wait! The density reaches the ultimate speed limit (according to my theory) where the escape velocity would be the speed of light, and then it stops contracting. It wants to contract, but it can't. It doesn't have time to. Time slows down in there. But outside the inner core where the escape velocity approaches the speed of light is a region where contraction can continue, and it does. The neutron star material continues to accumulate there. Until that density gets too high and the escape velocity approaches the speed of light, and then that layer stops contracting.
See the pattern? A region of contraction moves its way outward from the center of the star, at every point on its surface the escape velocity is practically the speed of light. This is what halts contraction. This goes on until all of the mass of the star has been consumed, it's effectively either neutron star matter or very much would like to become neutron star matter, but can't because it doesn't have time to. Always, that is, from our point of view. But our point of view is the only one that matters. If it takes an infinite amount of time for the matter to contract, then it can't contract. Before that happens, something else will have occured. In an infinite amount of time, anything can happen.
But we don't need anything close to an infinite amount of time. Because as I talked about in the second essay on black holes (mentioned above, the one about cosmic recyclers), the black hole is constantly spewing out hydrogen (and probably a bit of other small atomic weight matter like helium). This is eating away at the mass of the black hole. Bit by bit the black hole is blowing itself outward. As its mass decreases, the escape velocity on the surface falls below the speed of light, and it can contract a bit more. This process goes on and on and on, until so much matter has been spewed out in the form of hydrogen (and etc.) that what's left is a gradually cooling neutron star with a surface escape velocity well below the speed of light. Then everything stops.
There is a period where the mass is very, very much denser than neutron star material. There is some point, according to theory, where even the mutual repulsion of the neutrons isn't enough to prevent the neutrons themselves from squeezing into each other. I think the mechanism that gets overpowered is the Pauli Exclusion Principle, and it's why you can't have two electrons occupying the same quantum state in the same atom. I've got issues with that whole theory too, by the way. But one thing at a time... Anyway the thing is the density can be so high that it is even beyond the density of packed neutrons. That density is unstable. The neutron star is itself stable. You get enough neutrons packed together and their mutual gravity holds them in place as a big atomic nucleus. But that mechanism isn't enough to overpower the Pauli Exclusion Principle forever. The pressure is just too great. The mass wants to blow itself apart.
What stopped the constant increase in density was the time dilation due to the escape velocity approaching the speed of light. But you still have a really, really dense mass, more dense than neutron star matter, and it's evaporating. Here's the magic: There comes a point where the escape velocity at the surface of the mass moves from being practically the speed of light, to comfortably below the speed of light. That is, the mass is not trying to contract anymore. It already managed to contract as much as it's ever going to. But once the surface escape velocity moves away from the speed of light (heading downwards), this really, really packed, dense matter, denser even than neutron star matter, blows itself apart. And as it expands, the escape velocity falls even more away from, below, the speed of light. So more hot, dense matter can escape. Can you picture it? Time is finally able to start advancing again, and it can't wait to make up for lost time. Faster and faster the star blows itself apart. Kaboom! The supernova.
You're left with a stable mass of neutrons, the neutron star. What was blown away was the part of the mass that was squeezed so much it overpowered the Pauli Exclusion Principle. And it is blown away in an instant. A fireball forms. Temperatures into the billions and higher, mass more than the mass of our sun spewing outward. You get heat radiating from a sphere approaching a significant fraction of a lightyear. A supernova. A last, final gasp from an evaporating dark hole.
ETA: When I was first thinking about this stuff (earlier today) and imagining how I'd structure this essay, I envisioned making a point about the Standard Model, and our understanding of atomic and subatomic particles and their behavior, but as I wrote this essay it didn't come up. But I still want to get into that, so here it is.
The Standard Model is my understanding of what we humans consider to be our best effort at understanding what the hell is going on when things are very small, times are very short, and energies are very high. It's the theory that gets into the Weak Force, The Strong Force, The Electric Force, and Gravity (maybe not so much gravity). It's the thing that offers an explanation for radioactivity, and why some isotopes are unstable but others are stable. It's the one that lists all the known particles that can be observed when you smash atoms together at high speeds, and it's the thing that makes a pretty good effort at predicting their measurable features. It explains the energy states electrons in an atom can have, and how they jump back and forth among them, and what happens. It deals in quantum numbers and it predicts so many details of how atoms behave. It predicts the conductivity of the different metals. It explains why iron is magnetic. I think Roger Penrose characterized the Standard Model as Superb.
The wonderful thing about The Standard Model, is that it is directly subject to experiment. We can build big machines, atom smashers, that replicate energies far beyond what would exist in the core of our own sun. And we can observe what happens when we smash these atoms together. We can reliably and accurately measure the energy (frequency) of any light released in some atomic or subatomic reaction. We can observe so much detail, right here, on earth, in the laboratory, that if The Standard Model was even a little bit inaccurate we'd know it immediately. As such The Standard Model is what's left after a whole lot of smart people (scientists) did everything they possibly could to disprove theories, and couldn't. Or at least, couldn't yet.
I have faith in The Standard Model, and that faith is entirely because it is subject to experiment.
I have absolutely no faith whatsoever in String Theory, Dark Matter, The Big Bang, The Idea that Quasars are very bright and very far away, Dark Energy, Black Holes, The belief that increasing Red Shift with distance is caused by increasing receding velocity, and probably quite a few more. And the reason is because those theories are not subject to experiment. They're just a bunch of people who think they're really smart playing around with math and equations. But none of them are Truth. Truth is something holy. There can be no Truth unless it is subject to experiment. I've said this before, that when theories are subject to experiment, humans always arrive at the truth. But when theories are not subject to experiment, humans never arrive at the truth.
For me The Standard Model isn't even a theory. It's an algorithm. It doesn't even try to explain what the hell is going on down there, in the very small. It is a method by which one can predict, very, very reliably, what would be the outcome of a very, very large number of possible experiments that could actually be performed. But the machinery of what gives rise to the observed behaviours? It doesn't even try to offer an answer to that. That's why I don't even consider it a theory.
Understanding is not simply prediction. I come from a background of computer programming, computation. To me, unless a theory can be simulated, it isn't even a theory at all. Newton presented the world with equations for the gravitation forces acting on masses drifting in space. His equations can be simulated. And so NASA can predict years and years in the future where each moon of Saturn will be with enough accuracy that we can shoot a probe there, and after many years it arrives almost exactly where we thought it would be. Now, in that case I'm not sure if Newton's theory of gravity would suffice to that level of accuracy. In fact I doubt it. So NASA would have to take into account Einstein's adjustments. But for all intents and purposes, that's enough. It gets the job done. We can simulate the solar system and so predict for quite a few years ahead where everything will be.
But neither Newton or Einstein offer an answer to the question of why?. Why is there gravity in the first place? Why is there anything? At least gravity can be simulated though. So the theory of gravity is subject to experiment. But The Standard Model? It's a hodge-podge, a mess, a hack, a kludge. A collection of unconnected pieces that all sort of work together. A scientist can pick the right tool from The Standard Model and he can work out what the outcome of almost any experiment will be. But simulating space itself? We haven't got the faintest idea how to do that. The observable universe is what, like 10 or 20 billion light years in all directions, but we can't even simulate what space is doing in a cubic micron?
But that's what I'd accept as understanding. If you could simulate an electron and a proton as constructs that exist within something that behaves like space, and if you can set up your simulation with all sorts of viable configurations, and if it exhibits all the actual behaviours we can observe in real electrons and protons, then I think you'd be off to a very good start in terms of really understanding how the universe works.
Science, as tought in schools, I now understand to be a ridiculous farce. It is in reality just mental exercise. Most math has no practical utility. But being able to concentrate on math problems, puzzle out the answer, to get practice thinking? That's the true value of teaching math in school. It's exercising your brain. But science, as taught in school, is worse. Math, at least, rests on a foundation of bedrock. It knows when something can be proven unequivocally. But what is taught as truth, in schools, in the field of science... it's fol-de-rol. The only thing it has going for it is, it works. You can get through college with an engineering degree and the tricks you will have picked up will allow you to function in this world as an engineer. You'd know how thick a copper wire you'd need to deliver power to a town of 10 thousand households. You'd know how much water the town would need to consume in a typical year, and you'd know how to go about building the infrastructure to deliver it. You'd be able to design machines with a good chance of working the first time. You'd be able to earn a living as an engineer.
But does that mean you understand the machinery of the universe? Absolutely not. But students are conditioned to believe that having passed a class on Einstein's special relativity means they now understand special relativity. Utterly false! It only means they know how to solve word problems involving relativistic effects. But how does predicting what a moving electron would experience near an infinite wire with a steady current flowing along it allow you to understand how all the trillions and trillions of electrons and protons in the tiniest smidgen of copper jostle each other when the copper is at room temperature, and then also when it is at the temperature of liquid helium? It doesn't. The problems we are exposed to in school are ridiculously trivial. They're chosen to be solvable. To give the student the illusion of understanding, of control, of being able to do something useful. But most interesting problems today are nontrivial. They involve billions or trillions of interacting entities, all running on simple rules, but together giving rise to unexpected complexity. There are no infinite wires running along the X axis carrying a current I in the real world.
And you don't get to say You don't need to consider what each electron does to every other electron, because in a statistical sense it all averages out, and all that matters, when you get huge numbers of things, is the combined behaviour. That's a cop-out. Tell me how 20 electrons interact with each other if I give you their starting positions and velocities, and it better work when their velocities get close to the speed of light, otherwise you don't really know what's going on. You haven't discovered the Truth.