So, 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!

I think it was in the book Pale Blue Dot by Carl Sagan where I read that why the planets orbit in circular motion is because they are the planets that survived what must have been a chaotic early universe.

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.