address@hidden wrote:
>
>
> > Consider a system described by 2 languages which we call "microscopic"
> > and "macroscopic". Furthermore, we suppose that the system is
> > completely described by the microscopic language - true in the case of
> > an agent based simulation for example, arguably less true of a real
> > world system, where the microscopic description is probably expressed
> > in terms of an approximation like classical mechanics.
>
> > If some concept or property in the macroscopic language is not
> > contained within the microscopic description, then it is emergent.
>
> I am very interested in this approach to emergence, but it seems to me
> that the term language might not be really appropriate, or might be well
> defined.
> I think that emergence concerns more with concepts, phenomena and
> perceptions.
I use the term language advisedly. There are two descriptions, each
coded in its own language. Emergence is a property of the descriptions
of a system, rather than the system itself.
> At firts we must observe that the micro and macro world must have some
> relation. We might try to define this relation as "class and subclass".
> So any element in your microworld must be defineble, in some way, as
> belonging to a subclass of the macroworld (class).
There is a relationship between the two descriptions, although it is
not necessary for this relationship to be explicitly known. eg the
relationship between neural activity and the mind is not known, but
widely supposed to exist. Therefore, the mind is an emergent
phenomenon of neural activity.
> We can recognize emergence only when we can "percive" it, thus we need
> an "observer".
> Now we have a macroworld (class) built on microworlds (subclasses)
> interacting, and an *external* observer.
From the above, what I assume you mean by class is an equivalence
class of microstates that an observer defines. I'm not sure this is
necessarily needed for the concept of emergence, but it does play an
important role in the definitions of entropy, complexity and information.
>
> I think that what you mean with langage, is the definitions of
> subclasses properties and their interactions.
> Thus a new concept or property in the macroworld langauge is just
> a new way to define the class. This is done by the observer (an upper
> class) *after* the perception of the need of a new concept or property.
> You can't speak about temprature if you can't feel the difference
> between hot and cold.
>
> So i think that we might say that emergence occours when the observer
> recognize a "pattern" while observing the class.
> In the case of temprature the pattern might be mean energy.
>
Exactly.
> This approach might be more general since it allows emergence in the
> microworld.
> When the water boil (the macro property "temperature" goes above 100°C)
> something "new" emerges even in the microworld.
Sorry - what is the something new? at >100\deg C, the individual water
molecules are still interacting with each other with hydrogen bonds,
and moving through space following Newton's laws of motion. The
difference between liquid and gas phases are simply not visible at the
micro level. You can do this sort of experiment on a computer -
simulate a bunch of molecules which interact with some kind of force,
and satisfy Newton's laws of motion. At this simulation level, there
is no explicit description of phases. However, if you average over the
motion of a large number of such molecules, the behaviour we call
liquid and the behaviour we call gas emerges at different values of
the temperature parameters.
> In a social environment emergence happends even at the individual level.
> So we can speak about number of men, wemen, children, births, deaths
> ... at the macro level, but some "new" behaviour may "emerge" and become
> common at the microlevel. This behavior will than be described with
> the microworld language.
>
A society is made up of agents that are themselves emergent
collections of cells. Assuming cells may be modeled accurately by an
automaton (a better assumption than that of human beings), we simply
have 3 language levels, with some properties being emergent on the
middle level with respect to the lowest, and some properties being
emergent at the society level with respect to the middle level
(individual human). I don't see this as being anything but a simple
extension of ideas I've expressed above.
> Any feedback will be welcome.
>
> Matteo
>
> Universita' di Padova (DIMEG)
> Padova (Italy)
>
>
Cheers
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High Performance Computing Support Unit, Phone 9385 6967
UNSW SYDNEY 2052 Fax 9385 6965
Australia address@hidden
Room 2075, Red Centre http://parallel.hpc.unsw.edu.au/rks
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