[from Mary Powers 931118]
Bruce - that was a wonderful post.
Most importantly because it brings me to examine my remarks of
yesterday as possibly self-sealing (oh, good heavens, of course
not, how could that possibly be...)
Martin.
My hypothesis is NOT that Bill is always right. I should know,
after 37 plus years of marriage.
You say, abbreviating somewhat: Do Newtons'laws handle the
complexities of multibody dynamics? Sure they do. Can you use
them for this? Not easily. There are better ways. Likewise there
are better ways of handling issues in all these difference
(different?) fields (of the life sciences).
But this is so often used as an excuse and a rationalization for
NOT getting very far into PCT. We went round and round on the net
a few months ago about the specialness of social interaction and
how PCT couldn't possibly handle that complex phenomenon. No one
will ever find out how much PCT can handle if he makes up his
mind in advance that there are issues it can't. That's a self-
fulfilling prophesy. Also, maybe some issues look more complex
than they really are because they are being approached with the
wrong model - or no model at all.
Oded.
You say: What in the rules of the world (including the perceptual
machinery) makes this particular high-dimensional dynamical
system converge to a state (more precisely a region of the state-
space) where the signal matches its reference. This is the *why*
I referred to.
This is a wonderful way to talk about getting a cup of coffee.
Are you keeping in mind that *the rules of the world* include
control theory? Cup-of-coffee-getting is quite a bit beyond
present capabilities to model, but I refer you to the various
programs of Bill's and Rick's involving bacteria-like simulations
moving up gradients to get things they want, and the CROWD
program in which everybody heads for the goal and avoids bumping
into each other, and the "little man" who tracks a moving dot.
Have you seen any of these? All converging like mad on the state-
spaces that match their references.
By the way, it's a big mistake to say, let's explain something
really simple, like getting a cup of coffee. That task is homely
and familiar, but it is NOT simple. Let's learn Frere Jacques
before we tackle Beethoven.
(Parenthetically, anyone on the net who has NOT seen the programs
mentioned above, plus Demo I and Demo II, Tom's work and Rick's,
is missing a lot. The net is a fine medium for talk, but the
whole enterprise begins to take on the air of counting angels on
pinheads unless the armchair discussants get a little more real)
Mary P.