>Computer systems are, in general, necessarily dissapative. There is
>a subset of (mechanistic) computational processes ('reversible
>computations') that are not, but most software and computation is not
>restricted to this subset. Most computation involves a loss of
>information - this is necessarily so if you are using a finite
>computer for many computations.
It is important to realize that what goes on on a computer screen is an illusion
arranged in the mind of conscious observers. The program "Tierra" is no more
alive than the characters on a 2D movie screen. A very nice example which
illustrate its illusory nature is a phenomenon in relativity theory. One of the
propositions of relativity theory is that no information can move faster than
the
speed of light. This can easily be "disproved" by a convincing illusion.
Consider the following experiment:
Suppose we have a shining light bulb with a cap over it in a small room. There
is
a slit in this cap through which a small beam of light escapes. We see the
projection of this light beam on the wall.
Suppose now that we start rotating the cap until it reaches an angular
speed close to the speed of light. On the wall we would then see the beam of
light moving *faster* than the speed of light. Doen't this mean that information
can move fatser than light? Nope, the rotating beam is an illusion for it is not
really *one* signal but trillions of different unrelated photons that hits the
wall completely independent of each other. The light cone on the wall does not
move, but is the illusion of movement created by the exitations of independent
photons. Followingly the proposition still holds.
Similarly, the millions of different bits in a computer are completely
independent of each other. They do not interact. Any "dissipation" and
"information loss" are therefore purely illusory.
Onar.