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lmm comments on Open Thread, October 20 - 26, 2013 - Less Wrong Discussion
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Life "wants" to spread, so perhaps an increase in the volume in which life can be found?
Newly created islands may have "weird" biospheres initially, but evolve towards a more "normal" set of niches over time?
But why would life get more optimal? Evolution has finite optimization power, and it has long ago already reached this limit.
Huh? Even if you accept the estimates that your link points to, the amount of information in mammalian genome and optimization power of evolution are VERY different things.
How do you figure?
If you can narrow down the number of possible lifeforms to one in 2^n, that's n bits of optimization power, and n bits of information as to what the final lifeform is.
If life is getting more and more optimal, then we can simply wait until we know that less than one in 2^25 million lifeforms are that optimal, and we have more than 25 megabytes of information as to what that lifeform is.
You go and wait. I'll do other things in the meantime :-) Do you have any intuition how large that number is?
You've spent all that 25Mb for an index into the lifeform space but you have not budgeted any information for the actual description of the lifeform.
Imagine the case where there's one bit. It tells you whether creature-0 or creature-1 is optimal. But it doesn't tell you what these creatures are.
In any case, all these numbers are based on the resistance of Earth mammals to genetic drift. That really doesn't limit how evolution can optimize with different creatures in different places.
It's not going through them one at a time.
It's not a simple English description, but narrowing down the possibilities by a factor of two is always one bit of information. It doesn't matter whether it's "the first bit is one", "the xor of all the bits is one" or even "it's a hash of something starting with a one using X algorithm, which is a bijection".
It's the one with a higher inclusive genetic fitness. That's what evolution optimizes for.
If evolution has n bits of optimization power, that's equivalent to saying that if you order all possible lifeforms based on how optimal they are, this is going to be in the top 1/2^n of them. (It's actually somewhat more complicated, since it's more likely to be higher up and there's some chance of it being lower, but that's the basic idea.)
It does vary based on what lifeform you're looking at, since they all have different mutation rates and different numbers of children, but there's always a limit to the information, and I'm pretty sure that it's pretty much always a limit that's already been hit.
By my calculations, if you had the entire earth's surface covered by a solid meter-thick layer of bacteria for 4.6 billion years and each bacterium lived for 1 hour, that would be approximately 2^155 bacteria having lived and died.
You can massively increase genetic information (inasmuch as that actually means much in biology) very quickly with very simple genetic changes. It's not a case of searching through every possible 1 bit change.
Provided, of course, that your space of possibilities is finite and you know what it is. In the case of evolution you don't.
I don't understand what does "all possible lifeforms" mean. Does not compute.
Which limit? The limit of information in the mammalian genome? Or the limit of evolution -- whatever exists is the pinnacle an no better (given the same environment) can be achieved?