DCamer: переводы

→This involves a second A-Life principle: *local* control rather
than *global* control. Each flamingo has only a vague notion of the
behavior of the flock as a whole. A flamingo simply isn't smart
enough to keep track of the entire "big picture," and in fact this isn't
even necessary. It's only necessary to avoid bumping the guys right
at your wingtips; you can safely ignore the rest.

→For instance: the principle of *bottom-up* initiative rather
than *top-down* orders. Flocking demonstrates this principle well.
Flamingos do not have blueprints. There is no squadron-leader
flamingo barking orders to all the other flamingos. Each flamingo
makes up its own mind. The extremely complex motion of a flock of
flamingos arises naturally from the interactions of hundreds of
independent birds. "Flocking" consists of many thousands of simple
actions and simple decisions, all repeated again and again, each
action and decision affecting the next in sequence, in an endless
systematic feedback.

→The great hope of Artificial Life studies is that Artificial Life will
reveal previously unknown principles that directly govern life itself --
the principles that give life its mysterious complexity and power, its
seeming ability to defy probability and entropy. Some of these
principles, while still tentative, are hotly discussed in the field.

→The great thing about studying flocking with boids, as opposed
to say whooping cranes, is that the Artificial Life version can be
experimented upon, in controlled and repeatable conditions. Instead
of just *observing* flocking, a life-scientist can now *do* flocking.
And not just flocks -- with a change in the parameters, you can study
"schooling" and "herding" as well.

→Clearly the birdoids themselves aren't "alive" -- but it can be
argued, and is argued, that they're actually doing something that is a
genuine piece of the life process. In the words of scientist Christopher
Langton, perhaps the premier guru of A-Life: "The most important
thing to remember about A-Life is that the part that is artificial is not
the life, but the materials. Real things happen. We observe real
phenomena. It is real life in an artificial medium."

→You might say that the boids simulate flocking perfectly -- but
according to the hard-dogma position of A-Life enthusiasts, it's not
"simulation" at all. This is real "flocking" pure and simple -- this is
exactly what birds actually do. Flocking is flocking -- it doesn't
matter if it's done by a whooping crane or a little computer-sprite.

→They meander around in an unmistakeably lifelike, lively,
organic fashion. There's nothing "mechanical" or "programmed-
looking" about their actions. They bumble and swarm. The boids in
the middle shimmy along contentedly, and the ones on the fringes tag
along anxiously jockeying for position, and the whole squadron hangs
together, and wheels and swoops and maneuvers, with amazing
grace. (Actually they're neither "anxious" nor "contented," but when
you see the boids behaving in this lifelike fashion, you can scarcely help
but project lifelike motives and intentions onto them.)

→In 1987, Craig Reynolds, who works for a computer-graphics
company called Symbolics, implemented these rules for abstract
graphic entities called "bird-oids" or "boids." After a bit of fine-
tuning, the result was, and is, uncannily realistic. The darn things
*flock!*

→3. Don't bump into things, especially the ground or other birds.

→2. Try to move at the same speed as the other local birds.

→1. Stay with the flock -- try to move toward where it seems
thickest.

→But the "logical form" of flocking can be abstracted from its
"material manifestation" in a flocking group of actual living birds.
"Flocking" can be turned into rules implemented on a computer. The
rules look like this:

→Only living creatures perform the behavior known as
"flocking." A gigantic wheeling flock of cranes or flamingos is one of
the most impressive sights that the living world has to offer.

→Questioning "life" in this way may seem so much nit-picking
and verbal sophistry. After all, one may think, people can easily tell
the difference between something living and dead just by having a
good long look at it. And in point of fact, this seems to be the single
strongest suit of "Artificial Life." It is very hard to look at a good
Artificial Life program in action without perceiving it as, somehow,
"alive."

→And where's the "life" in an ant-swarm? Most ants in a swarm
never reproduce; they're sterile workers -- tools, peripherals,
hardware. All the individual ants in a nest, even the queen, can die
off one by one, but as long as new ants and new queens take their
place, the swarm itself can go on "living" for years without a hitch or a stutter.

→Amoebas aren't "mortal" and don't age -- they just go right on
splitting in half indefinitely. Does that mean that all amoebas are
actually pieces of one super-amoeba that's three billion years old?

→How about a national government, for instance? A
government can grow and adapt and evolve. It's certainly a very
powerful entity that consumes resources and affects its environment
and uses enormous amounts of information. When people say "Long
Live France," what do they mean by that? Is the Soviet Union now
"dead"?

→Bacteria are simple, as living things go. Most people however
would agree that germs are "alive." But there are many other entities
in our world today that act in lifelike fashion and are easily as
complex as germs, and yet we don't call them "alive" -- except
"metaphorically" (whatever *that* means).

→How about a frozen human embryo? It can be just as dormant
as a dormant virus, and certainly can't survive without a host, but it
can become a living human being. Some people who were once
frozen embryos may be reading this magazine right now! Is a frozen
embryo "alive" -- or is it just the *potential* for life, a genetic life-
program halted in mid-execution?

→Are viruses "alive"? Viruses can thrive and reproduce, but not
by themselves -- they have to use a victim cell in order to manufacture
copies of themselves. Some dormant viruses can crystallize into a
kind of organic slag that's dead for all practical purposes, and can stay
that way indefinitely -- until the virus gets another chance at
infection, and then the virus comes seething back.