Where that plays with universes?
I get that if they are infinite amounts of universes, the ones with conditions of evolving intelligence hace more chances to be observed from within, but more or less that’s it.
As an elegant way to solve the two problems, Wheeler proposed that mass/energy in a parent universe collapsed to form a black hole (thus leaving the bubble of space-time that was the parent universe). It then “bounced” at the singularity, and expanded in a Big Bang, to form a new universe – budding off a new bubble of space-time, outside of, and separate from, its parent universe.
That is, parent universes reproduced through black holes, which “bounced” to form Big Bangs. Each Big Bang was therefore the birth of a new child universe, which grew up to produce more black holes; more child universes.
In the 1990s, another brilliant American theoretical physicist, Lee Smolin, saw a marvellous implication of Wheeler’s idea that had been completely missed by everybody (because theoretical physicists don’t usually read much evolutionary biology; Smolin had been reading some, for fun). Smolin realised that if there was slight variation in the basic parameters of matter in the child universe (rather than the large and random variation assumed by Wheeler), you would automatically get Darwinian evolution of universes. That’s because slight variation allows for inheritance; and some of those slight variations would lead to more black hole production; more reproductive success; more offspring. Those successful variations would therefore be inherited more widely than less successful variations. The successful variations would vary again (slightly) in the next generation, with some variants being even more reproductively successful (and some less); and off we go – Darwinian evolution of universes, with the evolutionary ratchet optimizing for reproductive success. Over time, the majority of universes will come to be fine-tuned for very high levels of black hole production (compared to the evolutionary starting point, where the numbers could be as low as one or two). This seems plausible: our universe has already produced over forty quintillion black holes, just from stellar collapse. (That’s 4×10¹⁹; a four and 19 zeros! For how they worked that out, see Sicilia, Lapi, et al, 2022.) Smolin’s simple and straightforward evolutionary theory of universes became known as Cosmological Natural Selection (CNS), laid out in his paper Did the Universe Evolve?, and his book The Life of the Cosmos.
So, Smolin had uncovered a powerful evolutionary implication, hidden inside Wheeler’s simple model of the reproduction of universes.
We know how living things reproduce, but we still ask how life originated. Same thing.
How primitive can it be and still reproduce? Because to kick-start an evolutionary process, the only thing that it needs to do is reproduce.
How does a universe reproduce, in this model? VERY VERY SIMPLY. Mass-energy collapses to a point, bounces to form a new universe. All it has to do is collapse. So you have some primitive matter that collapses. It doesn’t have to collapse millions of times and produce millions of offspring (like our universe). Not yet. It just has to do it once. Flip/flop, a collapse and an expansion. A black hole/big bang cycle. And then eventually (and it has infinite time in which for this to happen!), it has to do it twice.
It produces two new universes. There’s two direct collapses that bounce to form new big bangs, new universes, right? And there’s no structure. There’s no complexity. But that’s a direct collapse, forming supermassive black holes. (Which is how, I argue, the supermassive black holes we find today in our universe must still form; evolution conserves successful reproductive strategies, she isn't going to invent a far more complicated way to do it, when a simple way is already available.)
That has to be how the earliest universes reproduced, without complex structures. All they have to do is just be a cloud of totally unstructured ultra-primitive matter, just collapsing. A directly collapsing cloud. No fancy nuclear fusion or stellar masses. And all that more complex stuff – stars, stellar collapse black holes, life, technology, technologically manufactured small black holes – comes later. They are later evolutionary breakthroughs. But they build on that earlier foundation, of direct collapse supermassive black holes.
I am sorry, but I can't help feel like this is a cop out. Much like "Its tortoises all the way down". Or "God created the universe and God always existed".
Making this original universe very simple does not help much, and it is just kicking the can down the road a bit. The fundamental questions still remains.
Wouldn't that mean each of the two universes have less matter than the one that spawned them?
(I'm not a physicist. Hell, I can't even spell physicist wihiut taking my shoes off. So this could be a very stupid question for all I know.)
If we're going to waive the need for a first mover, why not just waive it?
The key implication of cosmological natural selection: https://theeggandtherock.com/p/the-key-implication-of-cosmol...
And here...
A history of cosmological natural selection: https://theeggandtherock.com/i/158515951/background-lee-smol...
And if you prefer Youtube, I've talked about it here on the Infinite Loops podcast: https://www.youtube.com/watch?v=rZ5inYnDWWA&t=2341s (the link skips the biographical stuff and goes straight to the theory)
And if you prefer Substack, I've talked about it on The Weekly Anthropocene: https://sammatey.substack.com/p/interview-julian-gough-on-co...
Explore! Enjoy!
Nobody is saying right now that they’re sure this is happening. We have a seemingly very fine-tuned universe that warrants explanation. This is such an explanation, and one that is not only curiously simple, but requires only a small tweak to an existing theory which is plausible if untested.
That is inherently interesting even if we don’t have ways to test it yet.
So any universe expanding within a black hole of ours has to exist with only the mass that fell into it? How would it produce black holes itself with so little mass?
We know that in our own universe, the (positive) mass energy of matter and its (negative) gravitational energy net out to zero. But that means the amount of energy required to build a universe like ours is essentially… well, none. (See Laurence Krauss’s book, A Universe from Nothing; or Stephen Hawking and James Hartle’s 1983 paper, The Wave Function of the Universe, and Hawking’s later book with Leonard Mlodinow, The Grand Design, etc.)
Child universes are therefore effectively free to produce. Thus, over time, evolution will favor making more (and smaller) black holes from the same amount of matter. Yes, the black holes will get smaller – but the universes they give birth to, through Big Bangs, will still be full sized.
And universes aren’t constrained by a shared environment with limited resources – newborn universes aren’t all competing in a valley with a limited amount of grass. Indeed, each new universe is entirely self-contained and self-sufficient, being both organism and environment – it supplies its own energy for its own development, efficiently and frugally, through stellar fusion, gravitational collapse, et cetera.
This means evolution should ultimately favour runaway black hole production. (And that checks out: in the most recent estimate, in 2022, by a team from the International School of Advanced Studies in Trieste, our universe was estimated to have already generated up to a trillion supermassive black holes – and 40 quintillion stellar-collapse black holes.)
The low-black-hole universes aren't going to stop "procreating" because high-black-hole universes exist. At most, all you can say is that if you select a universe at random, it's likely to be a high-black-hole universe.
And I think you can use that fact to argue the theory's wrong: because surely our own universe is an LBH universe? A trillion is rookie numbers. There must be universes that produce vastly more black holes than ours, so the chances of us ending up in such an LBH universe at random are vanishingly small.
> And universes aren’t constrained by a shared environment with limited resources – newborn universes aren’t all competing in a valley with a limited amount of grass.
Yeah, that's what I'm trying to say. Without competition, it's not evolution.
That's a heritable trait, not selection pressure. Remember, we're talking about an infinite population size here, but if the pop. size was capped then the mechanism that decided who got to replicate and who didn't would be the selection pressure.
Can you ELI5 why you think the varying replication rate is, by itself, a selection pressure? Because your point's obviously going over my head, and your last comment did nothing to communicate it more clearly.
> At most, all you can say is that if you select a universe at random, it's likely to be a high-black-hole universe.
Yeah, that's sufficient when it's caused by their heritable properties. The proportion of high-black-hole to low-black-hole universes will approach 1:0.
Extinction is not part of the definition of selection pressure. Even in biology we still call it selection when a species merely gets pushed to the margins of an environment instead of driven extinct, or when a trait merely becomes uncommon instead of disappearing.