Bog'liq Kurzweil, Ray - Singularity Is Near, The (hardback ed) [v1.3]
Just how complex are the results of class automata? Wolfram effectively sidesteps the issue of degrees of complexity. I agree that a degenerate pattern such
as a chessboard has no complexity. Wolfram also acknowledges that mere randomness does not represent
complexity either, because pure randomness becomes predictable in its pure lack of predictability. It is true
that the interesting features of class 4 automata are neither repeating nor purely random, so I would agree
that they are more complex than the results produced by other classes of automata.
However , there is nonetheless a distinct limit to the complexity produced by class 4 automata. The
many images of such automata in Wolfram's book all have a similar look to them, and although they are
nonrepeating, they are interesting (and intelligent) only to a degree. Moreover, they do not continue to
evolve into anything complex, nor do they develop new types of features. One could run these for trillions or
even trillions of trillions of iterations and the image would remain at the same limited level complexity. They
do not evolve into, say, insects or humans or Chopin preludes or anything else that we might consider of a
higher order of complexity than the streaks and intermingling triangles displayed in these images.
Complexity is a continuum. Here I define "order" as "information that fits a purpose."
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A completely
predictable process has zero order. A high level of information alone does not necessarily imply a high level
of order either. A phone book has a lot of information, but the level of order of that information is quite low. A
random sequence is essentially pure information (since it is not predictable) but has no order. The output of
class 4 automata does possess a certain level of order, and it does survive like other persisting patterns. But
the patterns represented by a human being has a far higher level of order, and of complexity.
Human beings fulfill a highly demanding purpose: they survive in a challenging ecological niche. Human
beings represent an extremely intricate and elaborate hierarchy of other patterns. Wolfram regards any
patterns that combine some recognizable features and unpredictable elements to be effectively equivalent to
on another. But he does not show how a class 4 automaton can ever increase it complexity, let alone
become a pattern as complex as a human being.
There is a missing link here, one that would account for how one gets from the interesting but ultimately
routine patterns of a cellular automaton to the complexity of persisting structures that demonstrate higher
levels of intelligence. For example, these class 4 patterns are not capable of solving interesting problems,
and no amount of iteration moves them closer to doing so. Wolfram would counter than a rule 110
automaton could be used as a "universal computer."
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However, by itself, a universal computer is not
capable of solving intelligent programs without what I would call "software." It is the complexity of the
software that runs on a universal computer that is precisely the issue.
One might point out that class 4 patterns result from the simplest possible automata (one-dimensional,
two-color, two-neighbor rules). What happens if we increase the dimensionality—for example, go to multiple
colors or even generalize these discrete cellular automata to continuous function? Wolfram address all of
this quite thoroughly. The results produced from more complex automata are essentially the same as those
of the very simple ones. We get the same sorts of interesting by ultimately quite limited patterns. Wolfram
makes the intriguing point that we do not need to use more complex rules to get complexity in the end result.
But I would make the converse point that we are unable to increase the complexity of the end results
through either more complex rules or further iteration. So cellular automata get us only so far.