What Is Life? (2019)

In George C Williams' book Natural Selection: Domains, Levels, and Challenges, he starts the book with some philosophical problems for biologists. One of my favorites is that he points out a sharp distinction between the "codical" domain and the domain of "interactors".

Interactors are the physical organisms that interact with each other and the environment. The codices are the information stored in the genes. He makes this point to emphasize that the world of information has its own rules that are different from the rules of physical bodies, and that the interactors seem to exist merely to ensure the continued propagation of the information.

This is only a simple take on the life-as-a-computer metaphor. The problem is that it's only a metaphor.

If I follow you, this is basically the notion of a "replicator" that Dawkins talked about at length (and maybe coined?) - if you haven't read The Selfish Gene, I recommend checking it out.

Before all the details we need to arrive at the right ballpark and establish the basics. I know on my example that even though I got through school with good grades, I was still full of misconceptions due to a few key errors fed from teachers, bullshit pseudo knowledge I picked up from ufo+mystery magazines and TV edutainment.

So first, there is nothing special about life. Life doesn't break the normal laws of physics we use to describe everything else. Our naive concept is often along the lines of a game engine with inputs coming "from outside", from spirits or something. But there's no evidence of that. Living material is ordinary.

Physics teachers will explain that heat doesn't go from cold to warm places. If you ask how fridges can exist, they may say "well, heat doesn't go there by itself", invoking some kind of magic explanation. Now I know there are more precise phrasing in physics, but that's beside my point. We grow up with a concept that there are things that happen "by themselves" and there are things that happen due to living creatures' actions. In this implicit naive view that many, including past me hold, a fridge does an exceptional thing because it vaguely obeys our effortful engineering intentions. We make it do that, it doesn't do it out of its own nature.

Actually in primary school physics class when we learned the concept of forces, we learned different categories: magnetic, gravitational, "holding/mounting" force, friction force, muscle force... And we had to label the arrows in different everyday cartoons, like a kid pulling a sled in the snow: muscle force towards the kid, gravity down, holding force from the ground up, friction force backward. As if muscle force was some irreducible special magic phenomenon in physics. While correctly teaching basic school-level vector calculus skills they failed at teaching fundamental world view skills.

Because there's no distinction like this. Life doesn't violate the second law of thermodynamics.

Of course this article also doesn't claim that, but as I said, it's important to first arrive on the same page, in the same ballpark before the high resolution discussion.

I think it's desireable for there to be a zoo of definitions of life. Life isn't a precise mathematical concept, but a family of related concepts.

Self-replication is almost essential, but it's not hard to imagine a future AI that is highly dynamic, intelligent, etc, but does not create copies of itself.

Metabolism is pretty universal. I'd define it as a process that consumes free energy. Arguably viruses don't satisfy this definition. Computers do satisfy it. Most probably don't consider the sun to be alive though, despite it consuming vast amounts of free energy.

Minimizing internal entropy is an interesting one because it's not objective, it requires a model to define entropy. Something can look to us to be high and increasing entropy because we're using the wrong model to understand it. Viruses are static though, so they are definitely not decreasing internal entropy.