Re: Does anybody have any evidence that all evolutionary events are

Vend wrote:

On 10 Ago, 21:13, John Harshman <jharshman.diespam...@xxxxxxxxxxx>
wrote:

Vend wrote:

On 10 Ago, 13:45, John Harshman <jharshman.diespam...@xxxxxxxxxxx>
wrote:

Unpredictability

Chaotic systems are unpredictable unless you know the initial conditions
exactly. Are they therefore random? Not as the word is apparently being
used in this thread. Or can random events be grounded in strict causality?

Let's distinguish between epistemic and non-epistemic randomness:
Epistemic randomness is unpredictability due to our ignorance about
the system.
Non-epistemic randomness is unpredictability due to the fact that the
very mechanics of the system is non-deterministic.

Chaotic systems have epistemic randomness.
Quantum phenomena, in particular quantum wavefunction collapse,
possibly have non-epistemic randomness (it can be assumed so, although
the issue is not resolved).

Agreed.


Why do
you suppose that quantum randomness must affect selection and drift?

Because they affect all phenomena, and unless there is some
"averaging" effect, the unpredictability of quantum events will be
mantained and usually amplified in macroscopical events.

Then there appears to be an averaging effect, because macroscopic events
seem quite often to be predictable,

Some of them are.
Many interesting events are not.

Right. So we can't just say a priori that x is unpredictable or random
because it's underlain by quantum events.


and much of their unpredictability
seems to arise simply from our not having access to all the initial
conditions.

This would be the case if the underlaying laws were completely
deterministic.
If they aren't (as is appears to be the case), even perfect knowledge
of the initial conditions at some time t0 will not suffice to
accurately predict it at any t > t0 (unless t - t0 is very small).

This doesn't follow. It follows only if both of these conditions are
true: 1) the events are both underlain by quantum randomness and 2)
there is no buffering effect that insulates the phenomenon from
dependence on single quantum events. We may agree that (1) is true but
it's clear that (2) is often not true.

In principle it's possible for a system to be highly sensitive to
initial conditions and yet insulated from quantum randomness. Take for
instance a computer:
The electrons inside the transistors behave according to quantum
mechanics, and the quantum randomnes results in noise that combines
with deterministic thermal noise and others.
The logic gates made of transistors however, operate on just a few
(two or a little more) stable states that attract any other states,
damping the noise terms. Therefore, the logic gates and thus the
computer can be considered to operate deterministically.
On top of this computer, you can run a program that behaves
chaotically respect to the initial logic conditions
(a cryptographic pseudo-random number generator or a brownian motion
simulation, for instance)
This system would be practically unpredictable without exact knowledge
of the inititial logic conditions and yet shielded (with very high
probability) from the underlaying quantum randomness.

However, I don't belive that these are the kind of system we usually
find in nature.

I have already mentioned one such system: the gravitational interactions
in the solar system.

I think that the chaotic systems we usually find, for instance the
atmosphere, are sensitive to the minute physical details like the
position and momentum of the individual molecules (or perhaps
something a bit larger than that, but still very very small). At this
level of detail, quantum effects have significant influence.

This might be true, or it might not. I odn't know, and you have not made
a case.

Once I was told by a professor of Physics that if we have an ideal
cuesports table with the balls rolling and colliding without loosing
energy, if we alter the system by adding the gravitational field of an
electron at the distance between the earth and the moon, in a short
time the ball trajectories will differ macroscopically.

I find that hard though not quite impossible to believe. But "something
a professor said" doesn't make a case.

You may object that this system is unrealistic since it conserves
mechanical energy, but probably it isn't very different from a system
like the atmosphere with continous energy input and output.

<snip>

Lightning is an atmospheric phenomenon. Atmospheric phenomena would be
chaotic even if the underlaying laws of physics were completely
deterministic: a minmal difference of the state or the parameters at
time t0 causes a great difference at time t1, the famous butterfly
effect.

But chaos is not random, as I understand it. If the underlying laws
really were deterministic, the entire system would be deterministic
regardless of whether we were in practice able to predict it.

But the laws aren't deterministic, as far as we know.

It still doesn't follow that any given chaotic system is unpredictable
because of quantum effects. It would seem odd to me if, for example, the
orbits of the planets were dependent on quantum effects. They are
certainly highly predictable over long periods, even though the system
itsself is chaotic.

Planets are hold in one piece by gravitational and chemical binding
forces. I think that atoms are shaken non deterministically, but those
forces act like springs that tend to return them in their "resting"
position. As a result, the center of mass of the planet doesn't move
very much.
I planets with an atmoshpere, the center of mass of it probably
doesn't move very much since the atmosphere is gravitationaly bound to
the rest of the planet, but within the general shape of the
atmosphere, atoms are likely to be rather free to move. I can't think
of any global stabilizing force restraining them.

The point I'm trying to make is that your previous claims are not
universal features of chaotic systems. We can't just assume, in any
given case, that your ideas are correct. We have to investigate the
particular features of the system.

If laws are not deterministic, the small amount of unpredictability
that is introduced at every instant is not averaged away, but instead
its effect on the macroscopical outcome is amplified in a short time.

This may be true for some phenomena. It's certainly not true for others.
So there clearly are damping effects as well as amplifying ones. The
question is whether damping or amplifiying effects are operating in the
cases at hand. I don't see how you can be so certain either way.

Because we are considering systems that are chaotic, hence any
randomness is amplified.

This does not follow. It may be that the initial conditions to which the
system is so sensitive do not depend on particular quantum events, for
example.

Ok, but I think that unless we can indentify the layer where this
insulation from quantum randomess occours, we can assume that it
doesn't occour.

I think we can't assume any such thing. We can agree that we don't know.

.