Page 26 - Deep Learning

The Need to Override Experience 9

Time
Figure 1.2. Successive views of a meandering river and the creation of a circular lake.

move the river sideways. repeat this process at any point along the river where
the two banks are such that the waters flow at different speeds, and the result is
the snake-like shape we see in an aerial view of a meandering river. The river
might spin off a small circular lake where a bend becomes so pronounced as
to reconnect with itself; see Figure 1.2. Standing on the bank where a moun-
tain river meets a coastal plain, a wanderer can observe these component pro-
cesses without any other instruments than a pair of eyes hooked up to a brain.
nevertheless, the concept of a small, circular lake with an island in the middle
does not fall out of statistical manipulations of immense numbers of water
molecules. It is an emergent feature of rivers.
direct impact and cascading causation contrasts with a third flavor of
scaling called self-organization. This concept applies to a system that con-
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sists of a large number of similar components and the components interact
according to local rules that are the same for each pairwise interaction. Self-
organization also produces emergent characteristics. under certain rules, the
components fall together into structures that are stable and exhibit properties
that differ from the properties of their components. An anthill is the prototypi-
cal example. The intricate social organization of the hill does not follow any
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master plan but is created by the interactions among the individual ants. The
latter interact pairwise in accordance with relatively simple rules which, when
followed by thousands of ants, generate complex patterns that we, the observ-
ers, recognize as defending, foraging, nesting, tending the young and so on, none
of which exist at the level of the individual ant.
A fourth flavor of scaling is level-invariance. Some patterns are independent
of the material constitution of the relevant system, so they recur at multiple system