The two ideas do seem to be at odds. I think of the "persistence" of emergent features as being caused by basins of attraction. The strange attractors of a system subtly encourage all the agents of that system towards stability, through (perhaps) the efficient use of energy. But that would seem to be in line with increased entropy over time, and it's clear that there are local and/or temporary *decreases *in entropy at the heart of complex systems. Perhaps these are explained by perturbations in the system, either exogenous ones (like the amount of energy from the sun changing on daily, yearly, and decadal scales) or endogenous ones ... feedback from the system that is changing that system at a different scale than what produces the emergent property.
In Hugh's peloton example, the bicyclists form these groups, but they also get tired over time. Eventually, they all stop riding, and the emergent property dissipates. Or an ant colony self-organizes to find a food source ... when the food source runs out, this is a perturbation on the system, and they have to reorganize around a different food source. So maybe an emergent feature could be thought of as "temporary persistence." And free energy from the sun ensures a continual supply of perturbations on the earth. Probably two components would be enough to produce an emergent effect, but it wouldn't be a very interesting one. -Ted On Mon, Sep 7, 2009 at 12:28 PM, Mirsad Hadzikadic <[email protected]> wrote: > Now, I am somewhat confused. To me, persistence refers to a set of > features that continue to be perceived or exhibited, despite the > “rejuvenation” of the individual elements of the body that creates it. > Emergence, somehow, indicates an uncertain, possibly unexpected, outcome. > Also, persistence somehow assumes a long lasting pattern, while ( to me) > emergence may be short lived or even a one-time event. > > How many components would there have to be for a pattern/persistence to be > noted? Does it depend on the eye of the beholder? > > Mirsad > > > On 9/6/09 5:37 PM, "Russ Abbott" <[email protected]> wrote: > > In a recent discussion about emergence I wrote the following (somewhat > edited). > > Emergence is what happens when components of the emergent entity act in > such a way as to bring about the existence and persistence of that entity. > For example, when "boids" follow their local flying rules, they create (* > implement*) a flock. It's not mysterious. We know how it works. > > That's all emergence is: coordinated or consistent actions among a number > of elements that result in the formation and persistence of some aggregate > entity or phenomenon. The "coordination" doesn't have to be top-down. In > flocking, for example, there is local (or networked) coordination. The > flying rules for on each boid depend on that boid seeing neighboring boids. > One can even say that there is some overall coordination: all the boids > follow the same rules. > > It's worth pointing out that in biological and social emergent entities, > the components may come and go while the entity persists. What emerges is a > pattern of activities, not a physical thing. That's one of the reasons > people get confused. (And that's why subvenience is not particularly useful > in these cases.) > > But if you just think about emergence as a persistent pattern of > activities, that pretty much takes care of it. It's the fact that the > pattern persists that matters, not the elements that are acting to produce > the pattern. > > One of the more interesting issues in complex systems is the formation of > entities --. that "boid attraction" creates flocks is a simple example. > > With that in mind, it might be interesting to do some experiments. For > example, How dense does a collection of boids have to be for a flock to > form? Or more to the point, if the boids are confined to a limited, e.g., > toroidal, space, how does their initial density determine the rate at which > the flock forms? What about the other parameters such as the distance each > individual boid can see (that is, which boids become neighbors) and the > velocity at which the boids are moving compared to the "attraction" they > have on each other? This is like gravity and asking whether two passing > bodies will form an orbiting system or simply affect each other's velocities > as they pass and separate. > > What if the environment included obstacles that the boids had to avoid. > Some of those obstacles could presumably break up a flock. So how do flock > formation and flock disintegration interact? There might be other > disintegration forces such as boids moving a bit more randomly. > > How do these results relate to similar results in networks such as network > formation and connectivity, etc.? > > Do any "self-organized criticality" effects appear? > > Does anyone know whether experiments of this sort have been done, and if > so, what the results were? > > Having written this down, these feel like questions that should have been > asked a decade ago. But perhaps there might still be something there. Entity > formation is an open and important issue. Perhaps experiments of this sort > might shed some light on it > > -- Russ > > > > -- > Mirsad Hadzikadic, Ph.D. > Director, North Carolina Complex Systems Institute > Department of Software and Information Systems > College of Computing and Informatics > 343A Woodward Hall > The University of North Carolina at Charlotte > Charlotte, NC 28223 > USA > Work: 704-687-8643 > Cell: 704-340-0062 > Email: [email protected] > Web: cciweb.uncc.edu/~mirsad/ >
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