Saturday, February 21, 2015

Emergent behavior

Another line of research...

Emergent behavior is at the heart of Tiamat's Nest on two distinct levels. Charles studies collective human behavior, where large groups act in ways that bear no resemblance to how individuals behave. And the complexity of the global network hides a nasty surprise.

So what is emergence?

It's what often happens when lots of things interact, usually following very simple rules. Things start happening on the collective level that were not designed into the individual units or the rules by which they act. Entirely unexpected behaviors and properties emerge, as if by magic.

This is best illustrated with a few examples

Temperature and pressure of a gas are properties of the gas as a whole, not of any one molecule. They are macro properties that emerge from lots of freely-moving molecules bouncing around. The most remarkable thing about the ideal gas law is that the same equation relates temperature and pressure to the amount of gas in a given volume regardless of what the gas is made up of.

The whole inexhaustible science of chemistry emerges from comparatively simple quantum-mechanical laws governing how electrons, protons, and neutrons interact. So do such diverse real-world effects as the conductivity of metals, the blue of the midday sky, the violence of nitroglycerin, and the beauty of snowflakes. None of these could easily be predicted just from looking at how subatomic particles behave.

These are all physical examples, but have you ever been part of a large group of people where you've felt swept along by events that don't seem to be wanted by any individual you speak to, but which take place relentlessly nonetheless? Mob behavior is notoriously and dangerously unpredictable. "The tragedy of the commons" is a self-destructive property of pretty much any group with a scarce resource. Stock market booms and busts are more complex behaviors of the market that are in nobody's interest, but which emerge from lots of simpler financial interactions.


Pretty much anywhere you have sufficiently large collections of units interacting in some way, you can expect some unexpected properties and behaviors to emerge.

Charles studies the emergent behaviors of large groups of people, but where does Tiamat come into the equation?

Have you ever been driving down the highway when you met a line of slow moving traffic? After a mile or two of crawling along, things speed up again with no obvious explanation for the hold-up. You've just been part of a pressure wave, very similar to a sound wave in air.

Waves, whether in molecules in air, atoms in a crystal, or cars in traffic, arise from the molecules, atoms, or cars following a very simple rule: don't get too close to your neighbor.


This illustrates another typical feature of emergence - properties emerge from the interactions, the rules, regardless of what the individual units consist of. One name for this is substrate independence.

This principle is important because some theories of the mind reckon that consciousness and intelligence are emergent properties of certain types of information processing networks. If that's true, then there should be nothing special about neurons themselves. They are simply the substrate enacting the rules. Another substrate, say a complex enough computer network that happens to embody the right kinds of rules, should therefore exhibit the same properties - whether we designed it or not.

Now that's scary!

6 comments:

  1. A fascinating read. I'm not that into science but this was interesting.

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  2. As Stephen says, this is a fascinating read. I really felt I came away a little smarter - thanks. Every little bit helps.

    Cheers, Jenny
    2015 A to Z Challenge Ambassador
    @PearsonReport

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  3. That was interesting. And yes, I've seen those bottle-ups on the freeway many times.

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  4. Stephen, if I can appeal to non-scientists I cal that a win.

    Jenny, glad to hear it.

    Alex, those hold-ups always puzzled me until I realized what I was seeing. The fascinating thing is how those waves can travel for tens of miles back along a busy highway and last for hours after the original event.

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  5. Fascinating! It makes me think of hive behavior, particularly in ants and bees. I've always been fascinated with how these groups behave in nature. It's been an idea of mine to use such dynamics as emergent behavior with which to fashion an alien race in a far-future space-opera novel I'm developing.

    Nice work, Ian!

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  6. David, hive behavior is another good example. In fact Douglas Hofstadter wrote a scene in Godel, Escher, Bach, where one of the characters has a friend who happens to be an anthill, to illustrate the idea of emergent intelligence.

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