Last year, I wrote a speculative cosmology piece called Blowtorch Theory. It rather cheekily extended the American theoretical physicist Lee Smolin's wonderful, powerful, oddly neglected theory of cosmological natural selection; the idea that universes reproduce, with variation, leading to Darwinian evolution of universes.
While I was having dinner with my five-year-old, a friend texted to say that the piece was at number one on Hacker News. At the time, I didn't really know anything about the website, or its readers – but I learned a LOT over the next few hours, as my dinner went cold (and my son got to watch cartoons)!
Anyway, I greatly enjoyed (most of) the robust discussion that followed there, and thought Hacker News readers might be interested in this new Smithsonian Magazine overview of the remarkably healthy state of evolutionary cosmology, a new field emerging around these ideas. Think of it as a startup disrupting cosmology!
Discussion (26 Comments)Read Original on HackerNews
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.
The Blowtorch Theory: A new model for structure formation in the universe - https://news.ycombinator.com/item?id=44115973 - May 2025 (170 comments)
In the early universe, those planetary bodies must have been moving in different ways and colliding into one another, and the rate of collisions must have been very high.
Ultimately, the constant collisions led to eventual clearing off of bodies that did not move in circular motion, and that's what we see today. A natural selection of objects of the cosmos.
I might be misremembering Carl Sagan's description. But I'm almost certain I read this in Pale Blue Dot. I keep meaning to re-read that book.
Yes, I'm familiar with the multiverse idea, and I think I was first introduced to it in The God Delusion by Richard Dawkins.
I think the idea is plausible because if we have multitudes of planets, and multitudes of stars and galaxies, it might be reasonable to expect multiple universes as well.
Another idea which I've read about, and I think still in the God Delusion (but it might have been a Carl Sagan book, I don't quite remember), is that perhaps there aren't multiple universes currently existing. That is, there is no multiverse, but the universe, following the Big Bang, expands up to a point and then eventually collapses in a Big Crunch, and then explodes again in yet another Big Bang with different variations in its laws of physics.
In some of these new iterations of the universe, life as we know it cannot emerge; but in certain configurations, just as we have in this current universe, life has the necessary physical constants and environment to emerge and eventually be able to contemplate the universe that gave rise to it.
The strong Anthropic Principle is an interesting concept, but it's unfortunate that we have insufficient or even no evidence for any of these postulations.
I don't know if you were already familiar with the idea of an infinite series of Big Bangs and Big Crunches instead of the existence of parallel universes (a.k.a. multiverse), but if you weren't, it's the reason you sometimes see the Big Bang defined as something as -
"the cosmic explosion that marked the beginning of the universe or its current iteration."
The "current iteration" stated in those definitions refer to the idea just expounded.
Thanks again for sharing, I love reading about the universe, even though I'm not a physicist.
A "big crunch" sounds awfully like all the matter in the universe ends up in one gigantic black hole. And maybe when all the matter in the universe is inside one black hole, then gravity gets weird because there is no "outside" matter to maintain the integrity of the black hole. So the black hole then can just "explode" in a "big bang" from the pressure inside. Just a random theory from a non physics person.
In three, angular momentum in one axis is maintained. Everything else cancels out. More, and you get clouds.
It's strangely tautological to me but I only have my lifetime to consider, not the age of the solar system.
So what we are seeing here is a strong, simple, robust, self-stabilising system that should automatically build out large numbers of potentially habitable worlds in every solar system. Order automatically emerges from randomness, and is automatically maintained. There’s no delicate single-point-of-failure to worry about. No precise, narrow Goldilocks zone you have to stay in. But of course, the question then is WHY are the basic parameters of matter, and the laws of physics, tuned so that this is the natural result! What tuned them? I would argue, evolution is the answer.
For those interested, I've written further about this here: https://theeggandtherock.com/p/life-without-stars-stanets-an...
https://en.wikipedia.org/wiki/Titius%E2%80%93Bode_law
https://en.wikipedia.org/wiki/Musica_universalis