Forces of Nature
The fine tuning problem
In physics 101 I learned that there are 4 fundamental forces in nature. Gravity, electromagnetism, weak force and strong force. Each force applied in certain contexts. Gravity for instance applies to anything that has mass and extends to infinity, but is very weak. On the level of everyday speech this isn't hard to understand. But what makes something have mass?
I think Einstein figured it out with General Relativity. I've looked at the math and it seems reasonable to me - but it's math that talks about the possibilities of something. But never really says just what that something is other than giving a list of properties. It's sort of like describing a bicycle with a list of properties like "it's rideable" and "its longer than it is wide" but never knowing just what a bicycle is. I'm cool with that. What we know via the math works very well. But still, I'm curious about what's going on.
As I learn more about Natural Selection I'm coming to think of it as 5th fundamental force in nature. But it's a force we can understand without really opaque math. But we can only get that understanding if we are very clear about the ideas. With math there is that clarity but at the price of unvisualizable abstraction.
Daniel Dennett talks about Natural Selection as an algorithm; the Evolutionary Algorithm (EA for short). First point of clarity is that this sort of evolution is not progressive change in a physical system, like water cooling in a pot or dust conglomerating to form stars. Gravity accounts for that but gravity can't make a butterfly. The EA does account for butterflies.
The EA is an algorithm. In computer programming an algorithm is a set of instructions that do something. But we all know about algorithms - the way we do arithmetic with pencil and paper is a set of algorithms. If you want to know the sum of two numbers then write them out in a particular way and then perform an addition operation. That addition operation is another algorithm - a set of instructions that do something. Algorithms are substrate neutral. That is, I can add whether the substrate is paper, or birch back or slate. What Dennett saw (and Dawkins before) was that Darwin's expression of Natural Selection was an algorithm. The EA is a loop. You have something that is a replicator, that is, it makes copies of itself. The copies are not perfect, each is unique within a range of variability. Then you select which copies that best fit a set of criteria as the things to copy in the next iteration of the loop. What a loop like that does is the copies or replicators get better and better at meeting the selection pressure.
Darwin recognized the EA happening in biology. He wasn't a computerist and so didn't think in terms of substrate neutral algorithms.
But he looked and documented very well how the EA works in biology. His statement of how Natural Selection works is wonderful. Let me quote:
"It is interesting to contemplate a tangled bank, clothed with many plants of many kinds, with birds singing on the bushes, with various insects flitting about, and with worms crawling through the damp earth, and to reflect that these elaborately constructed forms, so different from each other, and dependent upon each other in so complex a manner, have all been produced by laws acting around us. These laws, taken in the largest sense, being Growth with reproduction; Inheritance which is almost implied by reproduction; Variability from the indirect and direct action of the conditions of life, and from use and disuse; a Ratio of Increase so high as to lead to a Struggle for Life, and as a consequence to Natural Selection, entailing Divergence of Character and the Extinction of less improved forms. Thus, from the war of nature, from famine and death, the most exalted object which we are capable of conceiving, namely, the production of the higher animals, directly follows. There is grandeur in this view of life, with its several powers, having been originally breathed by the Creator into a few forms or into one; and that, whilst this planet has gone circling on according to the fixed law of gravity, from so simple a beginning endless forms most beautiful and most wonderful have been, and are being evolved."
What Darwin saw was that the selection process that had been used since ancient time to breed better animals and plants Operated without breeders in the wild.
But it was Dawkins and later Dennett that noted that biology wasn't the only space where the EA can operate.
Dawkins introduced the concept of a 'meme'. A meme is a human behavior that other humans imitate.
Imitation provides the replicator - a behavior is copied from one person to another.
Imitation is often imperfect - that provides variation
And some of the varied imitated behaviors are more effective than others at doing whatever they do - that's a selection pressure.
The typical example of memes were the "Nigerian Emails" of years ago. These were scams that tried to bilk people into sending thousands of dollars to the scammers - I'm sure you remember. The basic idea was the scammer was saying I have access to a huge sum of money that I need your help to transfer out of the country. All they needed was your bank and identity info and a few thousand dollars to cover bribes of corrupt local officials. I got those letters for years. I saw them evolve as various scammers tried to improve on the letters. They have been traced using the same tools that Neitsche used to study the provenance of documents. They did get better and better. The typos disappeared. The situation presented got more and more plausible.
I think that's the EA in action.
The point here is that whenever there is a situation where you have replicators, variation, and selection, then the EA will operate.
I can show how the EA is informs us about how cognition works - actually Dennett did.
But I can apply the idea to physics too.
There is this plausible idea of a multiverse - that there are universes that have all possible sets of physical parameters.
Ours is just one.
We find that the set of physical parameters that our universe depends on are fabulously fine tuned. All of them have to have particular values that have to be very very precise or the whole system falls apart. How is that possible?
Perhaps the EA can inform this problem
What if we treat each universe in the multiverse as a replicant?
what if each universe has a random set of parameters?
And what if only some universes have a set of parameters that are stable ?
What we would end up with is a residue of stable universes.
And we are one.
There may be others.
What do you think?