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Julian, I love your work and I found this essay endlessly fascinating. Before I say anything else, I must preface my commentary with the fact that I am not a physicist. Every corner of your essay you preceded with "Note for non-physicists", I smiled and waved. So from a physicists perspective, I may as well solely be a helpless meatbag to you. Perhaps like Will ignoring your long and delayed responses to his tweet (or to his X? what do we even call them now?), you too will ignore me and I will call you not an old grumpy man but a grumpy egghead. Jokes aside, I cannot provide commentary on your theory, so I hope I can provide feedback in the only other way I know possible and helpful. I pulled your content into a google doc and started going to work, giving feedback where I felt it would be helpful. I am through 5 of 16 pages so give me a few more hours or a few more days. My hope is that, should you decide to take snippets of this and turn it into a chapter in your book, that this feedback is any way shape or form, even in the slightest bit, helpful to you.

It is a pleasure reading your work and I admire your request for public feedback. https://docs.google.com/document/d/1wHiy37kXcrOmi28fSzRj29xOsEE9XOCNzQvCbh4q2zo/edit?usp=sharing

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Incredibly generous of you to get stuck in like that, and actually annotate the whole thing! I look forward with pleasure to reading your feedback. (Don't hold back, I can take it.) It's extremely useful to have a close reading by a reader without a physics background, to let me know what works and what doesn't, what needs clarifying, etc. Thank you Haley.

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Are you familiar with Robin Hanson's work thinking through the implications of the existence of aliens? https://www.overcomingbias.com/p/explaining-all-the-weird-ufo-aliens

Since your theory suggests that our universe is tuned to give rise to sentient life with the capacity to manufacture black holes, it heightens the mystery of why we don't see more evidence for them through our telescopes. Hanson does some impressive math to show what this implies. He's a very rigorous thinker unafraid to come to unpopular conclusions - I think you'd like him if not already acquainted.

Keep up the good work!

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Yes, I have followed Robin's thoughts on that subject with great interest. I do not always agree with him, but I greatly enjoy his writing on the subject. It's a pleasure to see someone taking this stuff seriously.

I agree with you, and Robin, that the Fermi Paradox – where are they? – is a tricky one. It's a genuine problem for any theory that predicts life throughout the universe. And my approach does predict that, so if we fail to see any sign of any life on other worlds over the next few decades, as the telescopes improve, and we start to get decent data on exoplanet atmospheres and so on, it would not be good for the theory. But there are some decent potential answers as to why we don't seem to see signs of advanced technological alien civilisations all over the place. (Yet.) Hmmm, I should probably write a post about this issue sometime...

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Apr 17Liked by Julian Gough

I agree with much of this and have stumbled here trying to find more posts on the finer details/thoughts that cosmological natural selection would lead to, seeing if anyone was writing along the lines of which I've been thinking.

Note: I know the subtitle of your article ends "so help me make it better", but I wouldn't want you to meaningfully take/present from the below as your own ideas. Not to be too up my own ass about my ideas, but they are meaningful to me.

Thoughts I've had along this area:

1. I do think the AP still has A LOT to do with the branch of universes we can find ourselves in. It's a prerequisite for this discussion that we are considering universes which eventually develop consciousness. If time can be thought of as real, then primordial blackholes generated in .0000...x% of the time of a galactic blackhole should far and away out-procreate universes with other types of blackholes which take astronomically (no pun intended) longer to form. If primordial black holes formed in 1 second and initial galactic black holes formed in ~500 million years, we're talking about 10^16 generations of primordial black hole universes before the first universe forms other black holes. One would theorize that the local maximum for black holes/child universes from primordial black holes would be extremely hard to outcompete / is probably the global TIME-ADJUSTED maximum. I can't find guestimates of the number of primordial black holes that could have been created, but given this natural selection / local maximum logic you'd think it wouldn't be wildly off in terms of black hole orders of magnitude we find from stellar/galactic black holes in our universe (this is pure conjecture, but if 10^16 generations of primordial-driven universes can occur for a single generation of galactic/stellar black hole universes, then I'm not sure anything but an insane order of magnitude jump would be enough for our type of universe to outnumber/outdenominator purely primordial driven ones.)

2. This might be an argument for dark matter as primordial black holes, especially if black hole universe generation is scale invariant (which it would seem to logically be, else finite resources/energy/matter runs out), and dark matter could be the 2nd/3rd evolution as you lay it out. If dark matter is primordial black holes, and each is enough to create a child universe, then it would stand to reason we'd have a universe as full as possible of tiny black holes. This might be a) an earlier leap than galactic blackholes (so 2nd perturbation or however you frame it), 2) also factor in to dark matter as a necessary condition for conciousness/AP, 3) be even more interesting if dark matter wasn't a meaningful/necessary factor for conciousness/AP (since that would be real evidence that there is primarily a weight towards more universe procreation and secondly a need for consciousness in order for us to be having this conversation). This could also be something of a testable hypothesis in terms of cosmological natural selection, at least in the affirmative (i.e. if dark matter does turn out to be primordial black holes, then the universe really does appear to be geared towards creating as many as possible). In the negative, I'm not sure it really disproves cosmological natural selection since it could be that dark matter was not an avenue for black hole creation, and dark matter itself might be necessary for optimal galactic black hole formation.

3. I'd argue that simulations are the next leap forward in fecundity as it relates to the AP. Universes which create intelligence to create universes add another factor here. Not sure how the cardinality stacks up against primordial, supermassive, or "common" black holes, and maybe it's not an order of magnitude difference, but even a small multiplier growing at the same exponential rate would dwarf the non-multiplier (non simulation generating) universes at some point. The time factors function differently here as we think of AP, since we are thinking of the time until we get to a level of consciousness approaching our own (for the sake of argument, 14B years) vs the time until we get to a level of intelligence able to create simulated universes (maybe 14.0001B years). So no longer are we comparing 1 second primordials to 500B galactic black hole universes, and we are able to pretty much negate the time factors here (it might make more sense to talk about the odds of the 2 non-simulating Bostrom paths over a time factor, though at that point I think number of simulated universes created by all intelligences is a much more important figure in the math than time to reproduce at this point). I take this to mean that some layer of our existence is likely a simulation but perhaps the majority are black hole generated, or not.

4. In my mind, tracing this all back, in the beginning there were two things: 1. uncertainty, and (maybe) 2. a stage (spacetime). (possibly also energy/matter/stuff as #3). If gravity can be thought of as the effect that energy/matter has on spacetime, then in the beginning there is an impossibly long randomness that takes place, and at a certain point matter/energy happens to find itself concentrated enough to rip a hole in spacetime/create a black hole child universe (in the same way that primordial black holes may work). (Gravity being the first force that becomes individually defined after the big bang is in my mind an argument for its evolution/existence before other forces). Eventually, a perturbation like the strong force helps matter clump together much more easily, making child universes far out-procreate prior universes (why it makes sense the strong force separates next after the big bang). [I theorized that order of gravity --> strong --> everything else to form stars/galactic blackholes before looking up the order of de-unification, though subconscious could have factored in]

Looking forward to any thoughts on the above.

Best,

Ben Dean

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Hi Ben, thanks for such a long, thoughtful response.

Yeah, the points you raise are good, and I have thought about them over the past few years. Are there potential universes (perhaps extremely distant from our own evolutionary line of universes) that generate lots and lots of primordial black holes? Well, maybe (the possibility space is vast, and in many respects unknowable); and if there are, then such universes would indeed vastly outnumber our kind of universe, rather as rapidly reproducing bacteria vastly outnumber slow-breeding, long-lived animals such as ourselves. And in that case the anthropic principle would indeed kick in, hard. But that of course wouldn't stop a complex universe such as ours from existing, any more than the 70 gigatons of bacteria on earth stop a few thousand gorillas existing.

But our specific universe does not seem to produce lots of (very small, very early, maybe-produced-during-inflation) primordial black holes; we just don't see any of the micro-lensing events we should see if our universe contained huge numbers of tiny black holes. So there is a strong argument to be made that, down our evolutionary line of universes, the earliest black holes were supermassive or ultra-massive: ie, that our own extremely early primitive ancestor universes only produced a fairly small number of extremely large black holes, because that's the simplest model, and because it's really hard to produce black holes, especially in an early universe that has not been fine-tuned yet by evolution for reproductive success and efficiency. If that's the case, then all subsequent universes along that evolutionary line have to evolve downstream of that supermassive-black-hole-producing ancestor. How can they get to producing-huge-numbers-of-tiny-primordial-black-holes from there? Each step has to be reproductively successful, and it's not clear how you can produce both direct collapse supermassive black holes shortly after the Big Bang AND loads of teeny-tiny primordial black holes with the same parameters of matter.

My argument, that there are three stages of reproductive breakthrough visible in our universe – direct collapse supermassive black holes, stellar-mass black holes, and technologically produced black holes – with the black holes getting smaller and more numerous at each step, still seems to me the most likely to be true. There's an evolutionary path to that outcome that makes sense at each step. The smaller the black hole (and thus the more efficient the reproduction of the universe), the harder and more complex the process required to make it. The more evolved the process, in other words.

Which makes the overall picture coherent: the periodic table needs to get more complex at each stage. Matter has to be further evolved. Stage one black holes (direct collapse supermassive black holes) just need protons/hydrogen; stage two black holes (stellar-mass black holes) just need hydrogen, helium, carbon, oxygen; stage three black holes (technologically produced black holes) need most of the periodic table. And the conditions for life are confined to the most recently evolved regions of our universe and of our periodic table, the most-of-the-periodic-table-is-available-here planetary zone. It's satisfyingly coherent, and lots of primordial black holes just don't fit comfortably into that picture. Given that there isn't a clearly agreed route to how they might form, and we don't see lots of micro-lensing etc... I just don't think they exist.

I'll wrestle with your other points soon – they are great! I have a lot of thoughts on dark matter, and simulations! – but it's nearly 5pm, I have to go home, have dinner, put my son to bed, pack, and catch a train to the Netherlands for a few days, where I will be offline. So I'm not ignoring you, I just need to do some stuff and we will return to this extremely interesting conversation when I get back next week...

Meanwhile, I would love to know how you got interested in this subject. Does it connect with your day job in any way? Do you have any writing online that I can read? Please stay in touch, it's great to discuss these issues with people who have really wrestled with them, and I'd be happy to talk to you directly, by Facetime/Zoom or whatever.

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Hi Julian,

I'll definitely think more about your response and your 3 classes of black holes.

For the anthropic principal angle, I totally agree that a universe out-procreating ours doesn't take away from our own infinite line of universes. The core of what I was getting at there is that a condition of our branch of infinite universal perturbations is that it can have advanced consciousness.

I guess what I wonder here is at what point that condition for consciousness comes into effect. You'd assume that universes which were already well tuned for procreation which then developed consciousness down the evolutionary line would probably outnumber universes initially tuned for consciousness which later got locally optimized for procreation. I'm not sure and frankly I'm a bit under the weather and can better think through this later.

I'm definitely interested in hearing your thoughts on my other conjectures, and would welcome a deeper discussion. I've found it hard to find anyone digging in to the finer details of cosmological natural selection and I think it makes too much sense.

I don't post any thought or writing online, which is probably why I wrote a long reply here, hah. As for my background, it's decidedly not in physics or philosophy (I'm an entrepreneur and data scientist). I think I've just always had a fascination with the deeper questions (why is there something rather than nothing, for example) and always have thought of the word very statistically. I guess this is my sometimes hobby.

Best,

Ben

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Julian,

I've had a chance to reread your post and jot down my thoughts as I went through it:

This first point is where I'm likeliest to lose you :) A small point, but I'm not quite so sure 99.999999999999% of the universe is incredibly hostile to life. To risk losing you immediately, I believe in the zoological earth hypothesis (and that should we survive another 1-10k years we'd likely be able to see signs of biological life of nearby stars through telemetry and, with von Neumann probes, get eyes on nearby candidates, at which point we'd be unlikely to actively interfere.) After initially being a skeptic, I wrote a paper for a cold war culture history class that was going to be based on the parallel between numbers of reports of UFO sightings, body snatchers, etc. and news coverage covering Russian nukes and spies (i.e. Body snatches = an alien is among us in a similar way to a Soviet spy). My professor OK'd the proposal but told me if in my research I came to the conclusion that UFO sightings were real I could report on that instead, which is what happened.

Beyond that, I believe that most solar systems could have some life somewhere, and believe there is likely some other life in our own solar system along the lines of the possibilities posited in the book "Imagined Life" (Trefil & Summers). Note: later in your post you do argue that we are likely to find life in many places, in a potentially similar vein.

I very much agree that evolved universes will conserve many of the attributes that made it's ancestral universes successful.

Good point about the energy netting out to 0. I wonder if this was a necessary or evolved condition. I tend to believe that while it may not be strictly necessary, it's easier to explain the start of "somethingness" if at the very beginning matter/energy could spontaneously form/split from nothingness.

Agreed on removing the example which seems to be sexual selection. Instead...

... Could you not argue that a random walk with infinite iterations eventually gets you to a universe with intelligent life so long as the parent universes have a "cosmological fertility rate" (you can use this if you want, I might have made it up but I'm sure smolin or someone has probably written it before) above 1.0? Sure, they might not outcompete other universes, but we are playing an infinite sum game here. All universes spawning children with a fertility rate above 1.0 would likely have lineages that carry on. In the infinitity of possibilities of random walks, a universe like ours but without the final pieces catering for intelligent life would still likely have a very high fertility rate (see your conjectures from previous steps down the evolutionary tree). So I think you could just say eventually one of these fertility > 1 universes makes multiple fertility > 1 random walks/leaps (where we are starting with fertility rates of millions from primordial supermassive black holes alone, meaning we get random walks all over the place with high fertility rates) to get to intelligence-producing black holes or simulations, at that point becoming a dominant line. I think the non-zero sum game of it all plus infinite iterations allows for more leeway in random walking to universes such as ours (assuming we have/get to 3rd degree black holes). Your core argument of previous evolutionary advantages not being thrown out isn't negated by the reliance on random walks here, because high fertility rate parent branches would get the most play in terms of allowing for still fertile random walking.

Upon second reading I really like the idea of the black holes for energy efficiency. I might look into this a bit more. My initial skepticism centered on how great the leap is from black hole tech to antimatter/matter tech, in which case do we get away from this quickly or bypass it altogether? I will dig into the sources you give around bremsstrahlung radiation etc.

I like the point on the age of the universe and the age of earth being close.

For the local maximum argument, I'd argue given the random walk discussion above that we are likely to find ourselves in something that has such huge gaps between our local and a potential global maximum to make getting there all but necessitate crossing a chasm with at least one change that would have a fertility rate < 1 (i.e. No more black holes, making procreation in effect a non-starter)

With this talk of global and local maximums, I'm taking for granted that we are talking about universes capable of intelligence. That being said, I think getting to a more global maximum would probably mean going through some chasm with a fertility rate of ~0, regardless of whether that chasm allowed for intelligence or not.

For your argument that this resembles the anthropic principal but is completely different, my feeling is yes and no. Yes, universes with our laws will naturally outcompete others less finely tuned to life because life allows for higher fertility rates through either black hole reactors or simulations. No because we can only experience the subset of worlds where there is intelligence. But yes, of the subset of worlds we can inhabit it makes perfect evolutionary sense for the conditions to be fine tuned as they are. I think in the context of the tweet you reply to, it makes perfect sense. I think this could affect your point that most universes are likely to be complex because the complex ones are the most reproductive successful; I think they are the most reproductively successful in the possible worlds we could find ourselves in, but there is likely some mega (99.999..%) share of the pie chart that is filled with lifelessly reproducing universes which have even a slight advantage in generating 1st generation black holes, or generating them more quickly, just based on reproduction rates over a fixed time scale. If time isn't "real" then maybe this negates this, but then again that also could hurt your argument on the alignment of the similarity between the age of the earth and the age of the universe.

No Hidden Symmetry - I very much agree with this. I think we have some cobbled together laws of physics.

My random thoughts on the evolution/ordering of these laws: Maybe even there is a fractal element to the laws of physics, where big changes which caused great leaps happened first, and small iterations or specifics changing happened subsequently. My conjecture is that the order of the de-unification of the 4 forces after the big bang parallels this (gravity for black holes, strong force for matter to congeal/increase speed of random movements getting to density to make a black hole, then weak and electromagnetism to get to stellar mass black holes maybe?), but I do think there was wiggle room to get to our local maximum with random walks so long as the initial conditions continued allowing for fertility rate above 1 / an adequate number of primordial supermassive black holes.

All in all this has definitely helped me evolve my thoughts on this, and I'm be eager to continue this discussion and stay in touch.

Other random points still on my mind:

- dark matter as mini black holes: I am not an expert on this by any means, but I know there is a hypothesis that dark matter is made up of tiny black holes. If this is physically possible we might assume it to be the case.

- on simulations: I think the scale of these very much influences how they are maximized for. Will it take a ginormous computer the age of the universe to create one? If so, it's basically just like a single black hole. If not, and we/AI can run billions simultaneously (perhaps to follow the iterations to understand how we got here? Perhaps to do with simulations to negate the incompleteness theroum?), then these might become more of a driving force in how intelligence has been selected for.

Looking forward to our further discussion!

Best,

Ben

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Nov 10, 2023Liked by Julian Gough

Hi Julian, this was a pleasure to read as always. I’ve followed most posts now, so the lions share of what is presented here I am familiar with. The one thing that I don’t think has been fully addressed and I have been curious about is mentioned briefly in a note for non-physicists: how are black holes and subsequent universes made for “essentially nothing”? I appreciate your comment about mass energy and gravitational energy being equal, but as a non-physicist I require a bit more rigorous explanation.

This has been a question of mine for almost a year now (I first heard about your Substack and theory over thanksgiving dinner 2022). Until now I had been assuming that the initial universe was just so incredibly (infinitely?) massive that it allowed for the creation of the theoretical trillions+ of offspring universes. I had also been assuming that the black holes, when created were essentially gateways to the child universe, and all the mass in the child universe corresponded with the mass that had been sucked into the black hole. Upon thinking about this more it seems inconsistent with the overall theory, but I had not had another explanation presented to counter it.

Anyway, more explanation of how universes are so cosmically cheap to produce would be much appreciated. I may possibly see you in San Francisco next week. Cheers.

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First, Will Kinney's tweet did not deserve such a thoughtful response. Kinney said "One of the reasons I don't believe in the Anthropic Principle is, that almost all of the universe is savagely deadly to warm little meatbags like us." This is a huge misunderstanding the anthropic principle, which does not require that most of the universe be hospitable for life. Even if only one observer comes into existence, the universe is sufficiently hospitable to be observed. The anthropic principle does NOT say this is the best possible universe for life. It only says that this is at least no worse than the worst possible universe for life. This may be the worst possible universe that can be observed.

Second, if every black hole is a universe, that is very bad news for us. Most black holes merge with other black holes. We have already seen some mergers, with LIGO. If our universe is inside a black hole inside another universe, the probability is that our black hole is orbiting another black hole and they will merge. What happens to a universe when it merges with another universe, with different physical parameters? I don't expect that is amenable to life, in either universe. Smolin's hypothesis does not explain why we happen to be in a universe whose black hole has not yet merged with another. Of course, observer selection would explain that, but then you don't need the rest of Smolin's hypothesis.

Third, this is not the best universe for making black holes. If the strange quark were a little lighter, more of our neutron stars would instead collapse into black holes. This is evidence against Smolin's hypothesis.

Fourth, all discussions of cyclic universes need to consider the nature of time. Smolin believes that time is real and fundamental, but (for example) Hawking believed time is emergent. If time is not fundamental, then there still might be an assembly of universes, but to say that one happened before another makes no sense. In short, the deeper question is whether time is inside or outside of the universe(s). If all the possible universes exist "at the same time" then understanding any interaction between them will require new physics. It may be that the ensemble of universes has a resonance pattern that favors universes that minimally support life. This is the "extremely-strong anthropic principle."

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This is a great response Richard, packed with meaty points. I'm about to knock off the lights here in Berlin and go to sleep, but I will answer properly in the morning. I do have some thoughts on these issues.

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I have to agree with the fourth point about time. If time is in fact part of the self-organizing or fine-tuning nature of the physics in every universe that gets created, then does the idea of evolution of countless versions, some of which will have look more like ours, fall apart? It seems to me at least conceivable that time is just another dimension that could be adjusted on the fly to maximize the conditions (lots of stellar black holes) needed to drive complexification, like Julian said.

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Nov 1, 2023Liked by Julian Gough

That was a hell of a lot of fun to read and I think is vastly closer than you think. I wonder if you are familiar with the concepts of Constructal Law (proposed by Adrian Bejan -- there's a conference that takes place in Oregon every year encompassing some of the concepts of it). The elements within Constructal Law would certainly impact your proposition. In addition, I was reading one segment and wondering if some of the deformation/mutations of universes could be explained by an occasional small bleed-through from the "parent" universe. Even something on the level of a few particles could throw off the equilibrium, causing greater variation. Or perhaps there is a framework where universes may (stress may) exist in a cluster formation, with very, very minor impacts on one another (the universal equivalent of "sex"). Given that we're speaking about the birth of universes from a black hole into no space/no time, could that be possible? Ending this with just a "great work!" Really enjoyed reading this.

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Thanks Bill, greatly appreciated. Constructal Law is an interesting one. Yes, I have some thoughts on that, and on the recent paper by Hazen, Wong, et al, On the Roles of Function and Selection in Evolving Systems, which also tries to formulate a similar general law. I think something similar is happening in both cases... Let me get a night's sleep and come at this fresh in the morning. (I have a delightful four-year-old who leaps awake at dawn, so if I don't go to sleep ruthlessly early my life rapidly falls apart.) Absolutely delighted you liked the post, though.

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Mar 10·edited Mar 10

I love the way your philosophic, scientific writing resonates with truth, illuminating concepts with new perspective. I have tried to share your ideas, and with the exception of my 5 year old daughter and atheist best friend, they are rebutted with painful cognitive disodence; it physically hurts to contimplate that so much of what you *know* is inherently wrong.

If you haven't had the pleasure, please consider reading Paul Stamets 'Mycelium Running.' The similarity of the underground mycelial fungal networks one-cell wide, to brain cell pathways one-nueron wide, to a diagram of the computer internet one-computer wide, to the filiment like features modelled in some imaging of a younger universe one-solar system wide, to some visualizations of string theory dark matter. The intricately complex inter-connectedness is beautifully inspiring at all the levels humans are currently capable of imagining, so are likely to continue at all levels great, small, and far beyond our understanding.

It stretches many people's worldview to consider that the largest living organism on Earth is the Armillaria solidipes (Honey fungus). A mycelium network of this fungus in the pacific northwest spans 5.5 kilometres across, estimated it to be over 2000 years old. It stretches a worldview further to view this organism as an intelligent, communicative, keynote species in the biome. Imagine stretching this concept down to nuerons, and up to solar systems. Imagine still, as a network as grand as the universe or as tiny as quarks. I feel that networks like this extend beyond our human capacity to currently imagine, smallward, bigward, timeward, and universeward in directions and scopes our limited minds cannot fathom.

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Very interesting. One transition jumped out at me as needing more justification: the claim that a life-supporting universe will eventually have technology to generate small black holes, and that these will vastly outnumber naturally-occurring black holes, thus making the steps that lead up to them evolutionarily favored. My mind immediately asked: just how many technological black holes will there be in a universe like ours? Is it really "vastly greater" than the number of natural black holes?

To estimate an answer that question we need something akin to the Drake equation, with an additional factor to account for "proportion of technologically advanced civilizations that get as far as energy-producing black holes before becoming extinct". (There are times when I think that the odds of our civilization making it to the end of next week are slim.) Of course, this is extremely hard to estimate.

Then we must estimate how many black holes such a civilization would make. Obviously this is also very hard to estimate, but we should at least consider that making and managing energy-producing black holes is very hard and very expensive, and a planet like ours might produce only one or a handful. (For comparison, consider nuclear fusion: if energy-producing fusion reactors are much like current research projects such as ITER, very few countries or international alliances will be able to afford one, and even when the technology is perfected, they may be quite rare.)

Now, one might argue that "rare" is just fine: the overall hypothesis here implies that if it happens once, that universe will have lots of offspring. However, it's not necessarily the case that the rate of construction of technological black holes will grow in the child universes. We should consider the possibility that a universe where just a few technological black holes get built (or even none at all, because technological societies don't hang around long enough to get there) is sitting on a "local maximum" in evolutionary space, and that all the variations in the evolutionary space around that universe are worse for technological black holes, not better. In other words, the universes in which technological black holes dominate may not be reachable in evolutionary steps from this (or any other) starting point.

Anyway, the net of all that is that it's not a "slam dunk" that technological black holes will dominate over natural black holes. Once life gets involved (rather than "just" physics) lots of things can cause evolutionary paths to peter out. So that step, I feel, needs to be justified more strongly.

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Hi Jacob, thanks for this.

OK, this one is straightforward: I'm just going to disagree with you!

"Then we must estimate how many black holes such a civilization would make."

Cool, yes.

"Obviously this is also very hard to estimate, but we should at least consider that making and managing energy-producing black holes is very hard and very expensive..."

Yes... and no. Making the FIRST one is very hard and very expensive. But once you've pulled off that feat... you now have absolutely astounding amounts of energy available to make more. And have already built the equipment required. Pretty soon it's (relatively) simple and cheap.

" and a planet like ours might produce only one or a handful."

No. You are thinking way too small. Once you are able to control small, power-producing black holes, you are not going to stay on your home planet. You will, at the very least, transform your solar system. (Or, if you don't, someone else will.) And that will require a lot of small black holes to power a lot of highly dispersed environments that will need a lot of power either to maintain themselves, or to be transformed into very different self-sustaining environments. Think terraforming Venus and Mars, or building artificial worlds from asteroids. Work at that scale.

(For comparison, consider nuclear fusion: if energy-producing fusion reactors are much like current research projects such as ITER, very few countries or international alliances will be able to afford one, and even when the technology is perfected, they may be quite rare.)

No, again, you are not looking past the R&D stage. If we get working fusion reactors, we will end up with a LOT of fusion reactors. The current gigantic and inefficient experimental tokamaks, sure, we will only ever have one or two, because they are bad, early designs. Which is fine, that is the usual fate of prototypes. But look at earlier power-plant breakthroughs: China alone has 1,118 large coal-fueled power plants. There are over 400 large nuclear power plants worldwide, despite all kinds of regulatory and safety headwinds. (And over 150 extremely compact nuclear power plants driving submarines, for example, scattered about the globe: similarly, there will be multiple use cases for black holes as power sources.) No civilization ever goes to all that trouble to develop a more efficient new power source, and then only builds one or two. And small black holes unlock not just your solar system, but your galactic neighbourhood. Indeed, one of the first papers on this subject explored their possible use as power sources for interstellar ships:

https://arxiv.org/abs/0908.1803

You're going to need a LOT of small black holes, once you start things going on that scale.

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And I'm just going to disagree with your disagreement ;-)

I remain skeptical on two points (except its really the same point). There is no good reason to believe that engineering a fusion reactor will ever become cheap and therefore widespread. It's not just the cost of energy; it's the cost of all the materials required to make and operate a fusion reactor. And this is not merely a function of being in the R&D stage: this is a real attribute inherent in the physics and engineering of fusion. By contrast, with fission reactors there was always every physical and engineering reason to believe we could make smaller ones once we had mastered operating big ones.

Turning to black holes... we just don't know, because nobody has ever done it. Or even sketched out how it might be done. Maybe they will be like fossil fuel engines and come in every imaginable size at every imaginable price point. Or maybe the engineering and materials required to capture a black hole's energy output is so massive there's only enough resources to build one or a few in our solar system. Compare the challenge of capturing energy from the Sun: we can cheaply use only a small fraction of its energy through solar panels and (indirectly) wind power. To use all of it (or a large fraction of it) you need something like a Dyson sphere - and you only get one of those per solar system! For all we know, the engineering to harness a black hole for energy might be equally daunting.

Net: I remain unconvinced that having one black hole energy source allows us to jump to multiple black hole energy sources, because it's about much more than the energy budget.

Anyway. I'm not shooting at your whole theory. I'm just questioning the assumptions when you get to the bit that relies not on physics alone to do the heavy lifting, but on technology and engineering. I'm old enough to remember when we were promised that electricity from fission reactors would be too cheap to meter...

(Aside: if you want to terraform Mars, the first thing you're going to want to do is plant a small black hole at its core. Otherwise, there isn't enough gravity to retain a breathable atmosphere. Also terraforming Venus will take decades to centuries, if not longer, to turn its atmosphere into something even machines, let alone humans, can survive. Turning asteroids into habitats is much more viable. And then you tether two equal-mass asteroids together with a fiber about half a mile long and set them rotating about their center of mass to create artificial gravity on both of them without all the expense of building an entire circular space station like in 2001.)

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I also agree that the step from humans being able to make black holes to there being a vast number needs more justification.

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Morning here and the coffee hasn't kicked in yet. So apologies if this doesn't quite add up, but:

If intelligent life evolves towards making and controlling black holes, and these black holes come to dominate the number of possible universes, does that not imply a high probability that our own universe is one of those? That is, that we, and everything before and after us, lives and dies inside what might be called God's tabletop black-hole power generator? Not quite simulation theory (a fun idea, but I'm not overall a fan), but adjacent to it.

Then, if life /can/ evolve to control black holes - and does so for the purpose of energy generation - both of which sound reasonable to me, why would it seek to create the kind of black holes / universes which are themselves most hospitable towards life? I mean, if the type of black hole determines the type of universe it spawns, why would a species seek to create that particular type? (I guess you could run the argument in reverse.. a universe which creates species which create life-friendly black holes which in turn repeat the process is more reproductively successful.. which places "God" "Himself" within an ur-God's tabletop reactor, and so on).

And on mutation-reproduction-evolution - stating the obvious, mutations don't confer any advantage until they actually result in increased reproductive success. Evolution is generally understood to be lots of small steps (a mix of random and slightly advantageous) that - very occasionally - pass a tipping-point of some kind which opens up big new ecological niches, which lead to bursts of more rapid evolution.

Measured against this, the ability of a universe to create life complex enough to create and manipulate black holes feels like a bit of a "Eureka!" leap, like going from raptors to seagulls in one leap. The way I'm reading your framing, it would take many attempts to produce more and more complex life, but none of those iterations have any reproductive advantage. AIUI, the punctuated equilibria vs steady progress debate in evolutionary biology settled for "a bit of both", with mostly incremental change occasionally opening up a new niche resulting in rapid progress.. what I'm missing, I guess, is why there should be any selection at all in favour of complex-but-not-complex-enough-to-make-black-holes life.

Anyhow... thanks for a fascinating read!

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Thanks for your thoughts, Wulf. I have great respect for anyone who attempts to understand the universe before the coffee has kicked in.

I think I can answer your first point fairly easily. Lifeforms wouldn't need to "seek to create the kind of black holes / universes which are themselves most hospitable towards life". Simply creating a black hole of any size in a universe that generates complex intelligent life is likely to generate a child universe that also generates complex intelligent life, because the child universe automatically inherits the basic parameters of matter from the parent universe, with only very slight variation. Rather as a human child inherits the DNA from its human parents, and will therefore grow up to resemble its parents (and not a frog or a tree, with their very different DNA). That inheritance-with-slight-variation is the basis for any form of Darwinian evolution. And so, given that the basic parameters of matter in the parent universe generated complex intelligent life, so will the basic parameters of matter in the child universe. (There could be a variation, or mutation, in those parameters that is so disruptive to development that the child universe doesn't develop intelligent lifeforms and thus tiny artificial black holes; but that simply means that particular child universe will be, relatively speaking, less reproductively successful than any siblings without that particular variation/mutation. So such variations are not selected for.)

Your other point is more serious. You are quite correct: "...mutations don't confer any advantage until they actually result in increased reproductive success". So the leap to intelligent life that can manipulate matter is a hell of a leap, because until life gets complex enough to develop technology and manufacture small black holes as efficient energy sources, it isn't increasing the reproductive success of its universe.

That is, life in itself doesn't confer a reproductive advantage. Only sufficiently advanced life. So we are talking about a particularly extreme form of what, in DNA biology, would be called punctuated equilibrium. First put forward in 1972 (in a paper by Niles Eldredge and Stephen Jay Gould), punctuated equilibrium is the argument that species are basically stable for long periods of time, and any major change that generates a new species tends to be abrupt and dramatic, after which stability is restored (but now you have a new species).

Here's how I think it happened, but I'm keen to hear other ideas, because this is a very fuzzy, under-explored area, and I'm sure my thoughts can be greatly improved on.

When it comes to the evolutionary history of universes, life has to be downstream of chemical complexity. That is, the chemical complexity has to come first; life comes later. There is no complex life possible in a purely hydrogen-and-helium universe because the necessary chemical complexity is impossible. You can't build the requisite intricate structures; the range of bonds and potential molecules available is far too small. You need something like carbon, because carbon can build incredibly complex long-chain molecules. And you need some other elements with some other properties to attach to the carbon, to build molecules with different properties. Oxygen, for instance, is incredibly useful to complex life.

But, crucially, a universe can gain an evolutionary advantage from generating carbon and oxygen, even before that leads to life. Carbon and oxygen are important elements in the cooling of the molecular gas clouds (made mostly of hydrogen and helium) that allows those clouds to collapse to form stars. (Carbon monoxide – CO – acts as a refrigerant.) A universe that generates carbon and oxygen can make more, and smaller, stars, and make them much faster. Which means such universes ultimately make a lot more stellar mass black holes; they are more reproductively successful. So carbon and oxygen were mutations that were already being selected for, long before life. They are part of the first great step upward which universes made in reproductive success and efficiency – that from the purely direct-collapse-supermassive-black-hole universes to those more complex and successful universes where the direct-collapse supermassive black holes then generate the stars and galaxies that produce a second wave of smaller and more numerous stellar mass black holes. Carbon and oxygen make that second wave of reproduction inside the life of a universe more efficient.

The earliest carbon and oxygen, in primitive universes, might have been made in a number of ways – through the incredibly intense pressure and heat generated by relativistic jets around direct collapse supermassive black holes, for example – but they end up being made mostly in the core of those stars, through stellar nucleosynthesis.

Once there's a successful evolutionary line that is exploring the possibility space opened up by stellar nucleosynthesis – where stars are making elements like carbon and oxygen and nitrogen in their cores, then distributing it, through supernova explosions, to make the next round of stars – you are going to get more and more elements formed and distributed, just by random-walking through the possibility space. Planets turn up around this point. They don't have any huge evolutionary value yet, they're just stuff that is left over. And my guess is that evolution stalled out for a long, long, long time in this era. But, slowly, just mooching around the possibility space, you got more and more elements, and a more and more complex chemistry, and chemistry started to replicate at some point in some of these universes. This is a process of evolutionary drift, not particularly directed, at this point. Those universes with replicating chemistry might even have been doing worse than others, back then, in reproductive terms. (Just as mammals were not particularly successful for a long, long time, while dinosaurs thrived. Not an exact parallel, as they were in direct competition, unlike universes, but you get the idea.)

But you only need the breakthrough to complex life that can manipulate matter enough to make small energy-efficient black holes to happen once, on one freak planet in one freak universe, so long as the lifeform has a long time to spread, and convert a significant chunk of the matter in that universe into small black holes. That first breakthrough can be made accidentally, inefficiently, luckily; but once it happens, boom, there will be so much more reproduction along that line that the adjacent possible for that breakthrough will be rapidly and thoroughly explored. Complex life will be produced faster and faster, more and more efficiently, along the most successful evolutionary lines.

And by now, complex chemistry, and the elements of the periodic table, have been so fine-tuned that planets that generate complex life start to form not that long after the universe pops into existence. Our universe is 13.8 billion years old; our planet is 4.5 billion years old. And that's about as fast as you could make it: very complex chemistry! After the Big Bang, it took a lot of stellar nucleosynthesis of heavier and heavier elements, and distribution through supernovae, to generate the material for such a planet. And life is 3.7 billion years old. Again, you can't do it much faster than that. There was a lot of complex chemistry required, after the formation of the Earth from a cloud of simple dust, to shape the geosphere to make it ready for life and the biosphere. (And then the biosphere shapes the geosphere to suit itself.)

It's pretty efficient now, in the sloppy way of any evolved organism that has to retain many earlier features while changing. (Carbon still has to help the stars form, as well as help life develop. It's a compromise.)

So, something like that!

Whew. That took longer than I intended. I might tighten this up and make it into a post. Again, feedback welcome!

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OK - so the iterative evolution towards complex chemistry part sits well with me. That is, universes evolve towards producing more universes, and complex chemistry - indeed, complexity in general - is adaptive there.

A more complex (or more information-producing) universe produces more universes, which in turn selects for yet more complex universes.

I'm still sceptical about the _next_ leap though - because the implication is that our destiny as a species is one of vastly more deployed Watts/individual than the present day, and using that energy in stages to first clean up our own planet, then go interplanetary and finally interstellar. It may be a popular vision of the future, but that doesn't make it necessarily _right_. (You might be guessing by now that I don't, these days, belong to that camp - am more of the view that efficient information networks mean we can achieve optimum quality of life with _less_ energy per individual than people thought would be necessary a couple of generations ago - but at the same time, we need cleaner energy and a much more equitable distribution of it).

And also, well, I just don't dislike the God's-tabletop-reactor (and cousin of simulation theory) thing, but I should probably declare my own bias as the kind of atheist that finds more meaning and purpose in a universe without a Supreme Being, than one that has one.

As to punctuated equilibrium - there's no doubt from the fossil record that it takes place, it's more a case of to what extent it's endogenous ("great leap forward" de novo mutations) vs exogenous (mostly environmental changes/disasters opening up new evolutionary space for survivor species to explore, or occasionally some accumulated mutations leading to a point where the species itself can suddenly explore a new space - a proto-bird which eventually, thanks to generations of escaping predators, gets good enough at flying to island-hop, say, which in turn gives it a whole bunch of possibilities as to how to evolve next). It's debatable where that sort of case sits on the endo/exo spectrum - I'd look at that one as incremental endogenous changes passing a tipping-point which opens up transformational exo opportunities. The mammals were a bit different - they didn't take over because of some de novo mutation (indeed, they'd already radiated into dozens or hundreds of species by the time the asteroid hit) - rather, they survived the asteroid and were able to evolve into the new conditions.

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Thanks for sharing your interesting idea. You might find useful in the same line this: E.R. Harrison, "The Natural Selection of Universes Containing Intelligent Life," Quarterly J. Royal Ast. Soc'y, vol. 36, no. 3 (1995), https://adsabs.harvard.edu/full/1995QJRAS..36..193H. The title says, well, if not it all, the gist of it. Great minds, friend, great minds.....

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Jan 25·edited Jan 25

Hi! New reader (and layman) so perhaps I can't find an article or research regarding infinite universes. It seems tautological to me that if there are infinite universes then that alone explains every detail about our own universe. But I haven't seen any evidence that there is more than 1 universe - I had thought that was resolved when hubble found there wasn't going to be a "big crunch". Again, apologies if I'm just not caught up.

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sure, that all adds up

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Oh now this is good sir, very good. I have been marinating on this all day can't stop thinking about way's to dig even deeper provide even more proof. Let me know if you like any comments and ill notate them down.

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It's incredibly interesting, isn't it? I find it hard to stop thinking about it. There is so much to uncover; the territory is so rich, and has been so little explored.

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