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Comment by justinpombrio | Hacker News Reader

Evolution depends on a means of variation (in biology, random mutation), and on a measure of fitness (in biology, number of children). What would the means of variation and the measure of fitness be for laws of physics?

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Different abstraction level. Evolution provides a framework for biology which works at every level. EX: Why does the human optic nerve cause a blind spot? At the detail level biology is filled with a huge range of less than optimal solutions, but when 'it worked' is the only limitation things click.

Physics has a lot of data and several models that work really well, but they don't really fit into a single coherent system. QM vs Relativity etc. The density needed to form a black hole decreases linearly with radius, sho why is the universe not one?

> The density needed to form a black hole decreases linearly with radius, sho why is the universe not one?

I feel like this explains it pretty well.

https://medium.com/starts-with-a-bang/ask-ethan-50-why-didnt...

tl;dr: Schwarzschild’s solution is a static one, meaning that the metric of space does not evolve as time progresses.

I think more accurately, a measure of fitness includes a fitness filter (in biology, death). This raises another question - what would be the fitness filter for the universe?

Entities capable of asking this question?

Does lack of such entities kill a universe? If not, then we're just reducing the problem to anthropic principle here.

It's very likely that there's no higher purpose in any universe's existence - a/the universe could just be a set of random "rules and laws" which happen to not die out as soon as they are randomly created.

Of course verifying this probably requires that we inspect most of our universe directly...

Instability. Just like in biology, death is not a true optimization, it is greedy for local maximums. How many bacteria have evolved specifically to thrive on you, even though within a couple decades surely you'll be no more, leading them to extinction?

So would universes come in existance with varying degrees of stability. No one has to say 'this is a stable universe'. We can say 'this universe has been stable for quite a long while'. Long enough to spawn us and the very interesting universe around us.

Just like in biology, merely the fact that we could be here, is the reason we're here.

Of course, that's assuming that for some reason big bangs with varying values for universal constants are a constant occurrence. Unfortunately, this is not likely to be something we're ever going to be able to measure/observe. Though there are/have been (theoretical) experiments to see if universal constants really are constant. If they're not, that would be a nice indicator that the universe really is unstable enough to create stability.

As a poster said, the fitness filter may as well be "whatever works" in the sense that it's so rare to stumble upon stable combinations of energy, space and time (if they are at all separate concepts) that whatever works, continues existing, and if circumstances allow, spreads.

It's actually quite a neat concept, if very similar to the anthropic principle. Unfortunately, it offers no predictions.

Repeating what I've gleened from my extensive reading of sci-fi:

New child universes are spawned with new values for various constants. Stable arrangements (combinations) persist, spawning new grandchildren universes. Unstable arrangements blink out of existence.

Edit: I want to apologize for volunteering an answer to the question of how natural selection might work at a cosmic level with some speculation I've read. I regret the error.

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