Undergrad Emergence of Complexity and Life

[madness]

Just came across this, which seems very relevant. He's discussing KL-divergence, Free Energy, Fisher Information, Information Geometry, etc. in the context of biology:

 

[H_A_Landman]

I think the conclusion is overstated.
Perhaps "and so cannot comprehensively describe living systems" is a little less categorical and more nearly correct

I meant something more like "have little relevance for a complexity measure of living things". It's clear that organisms use/contain many fractal-like structures, so there is definitely relevance in ontogeny / developmental biology. But e.g. the final number of branches in a vascular system is mostly a function of how many times the "branching rule" got applied, which is not the same thing at all as how complex the rule itself is. It's the latter complexity that we're after. (There is some complexity in the "counter", but it's probably logarithmic in the number of iterations, so it's small and for some purposes we can ignore it.)

 

[Jarvis323]

I ask the OP to play a few dozen games of John Conway's cellular automata Game of Life.
Now consider how difficult it is to describe the complexity. How does all of the schmutz in these evolutions arise from such a simple system? Seems very unlikely but yet it happens over and over again in many different ways.
`I am nowhere near clever enough to even understand what is not understood. I don't even know what questions to ask...but I think entropy and energy are not sufficient.

If we are to consider Conway's argument, it is that the reason the game of life can produce so much complexity and variety, is that it is so simple.

 

[Jarvis323]

One has to be cautious using things like Life or the Mandelbrot set as models. Their Kolmogorov complexity never grows; it is always no larger than that of the initial conditions/equations. The idea that simple iterated rules can generate large apparent complexity is worth noting, but those models have neither energy flow nor a need to respond to changes in the environment, and so have little relevance to living things.

That does not seem true, that the Kolmogorov complexity doesn't change in the game of life. It seems easy to come up with counter examples. And in some sense it does seem to respond to changes in the environment doesn't it? Can you explain these arguments further?

Also, Kolmogorov complexity is only part of the picture (what is the shortest possible program to produce the objects) another part is something like logical depth (what is the minimum possible number of steps needed to produce the object). Kolmogorov complexity is akin to the amount of unique pieces needed to produce the object, while logical depth is akin to how complicated it is to assemble.

I think that in studying the complexity of life, something like logical depth is important. But that also depends on the system that computes it.

 

[scot]

Chaos is the law of nature. The real question is how is there any order in this nature at all. How do the most complicated system in our universe have laws that govern them? Where do those laws come from? It’s the watch maker theory. The fact that life on Earth exist at all is astronomical.

 

[Dale]

Ok, that is enough. 34 posts in and we still are vacillating on the specific meaning of “complexity”. And now this thread is attracting nonsense. This thread is closed.