OK, a few more questions and comments:

( Doug Goncz ) wrote:

rom: Bert

Just curious what your definition of "self-replicating" is, and where
that definition came from. Is anything other than the machines you
mentioned here included in the self-replicating entity that you
envision?

....snip of historical prelude and thoughts on identity

I'd learned about the power of exponential growth. We have only about 2^32
people on this planet, so if a machine could be replicated in a month, in 32
months, everyone could have one. And a fork, a bowl, and something to eat. It
was a very idealistic notion.

Yes, isn't idealism great? I'm guessing that at the time you weren't
too concerned with the concomitant exponential growths in the amount
of steel required for all those machines, the amount of associated
equipment and energy to mine and process the raw materials for that
steel, and the amount of energy consumed by the machines during
replication.

Unfortunately, even a sub-exponential growth in the population of us
"self-replicating" humans is beginning to create problems due to
resource scarcity. But that's a whole different topic.

But all of us here know our machines well, and I think it's not too far out to
say that a team assigned with reducing a set of pairs of machine tools to their
most compact configuration has to be tightly knit.
....
Thus the experiments with cross vise, drill press, collet indexer, and four jaw
chuck in 1995, in pairs.

I get the impression that, analogies to quantum mechanics
notwithstanding, the primary (or only?) requirement for having pairs
of machines is so that one machine can serve as a model or blueprint
while the other is actually being used for making parts. If that's the
case, why not add a pantograph (or other 2-D duplicating device) into
the mix and then replace one of each pair of machines with a set of
drawings or specifications? That would save you quite a bit of weight
(and expense) on your trip to Mars.

How much assistance or work by an external agent, and what
degree of pre-processing of raw materials and energy sources, can be
utilized while still meeting the qualifications for self-replication?

The only source possible, since the energy requirements for synthesis are
extreme, is nuclear. I can't go NUPOC. I'm too old to serve 20 years before the
age of 55. So I have to go NASA. Solar cells actually do not self-replicate.
Solarex tried it at their Rockville plant, near here. It wouldn't come off.

Electronics technology is self-designing, and thus Moore's Law, but it is not
self-replicating.

Why not combine electronics, machinery, and the requisite chemical
processing equipment into a system that is truly self-replicating, and
perhaps self-designing and self-evolving as well? That seems a much
more intriguing problem, though perhaps not as amenable to analysis or
near-term solution.

This seems as good a point as any to interject my personal bias
against the term "self"-replicating as you use it. To me, that term
suggests that the entity makes a replica OF itself BY itself (such as
in the reproduction by a simple asexual organism), whereas your
definition describes an entity that is employed to make a replica of
itself under the guidance and manipulation of an external agent. For
that matter, to the extent that your machine (or system of machines)
is involved, it is not making a replica of itself per se, but rather
is making a pile of replicas of its component parts, which must be
subsequently assembled and adjusted by an external agent to yield the
replica machine. Unfortunately, I can't at the moment think of a more
appropriate or palatable term for such a process.

The only thing I've left out of the QM analysis is the foundry. With unlimited
available power, the foundry is not a problem.

With unlimited available power, many problems go away!

Just as they leave out "spin" in QM in order to build a foundation for
multiparticle systems which includes spin later in the analysis, I am leaving
out the foundry for now, but will include it later.

Will you also include mining and other requisite operations, and the
equipment needed for those operations? How do you account for the
non-metallic components of the machines, such as the insulation on
wiring and motor windings, or grease, or rubber belts or bushings?

Wigner's paper analyzed exactly what Bert has asked, considering a machine or
rather configuration of matter floating in a "nutrient sea" of components,
which could be fundamental ingredients or parts ready to be final-assembled,
and concluded it was impossible for the configuration to replicate in finite
time with available ambient thermal energy.

I assume there are more constraints on the "nutrients" in this sea
than is implied here. Otherwise, instead of the solution being
impossible, it would be quite possible, and in fact trivial for
certain sets of machines and nutrients.

In any case, this is quite a different problem than accomplishing the
same end result with "unlimited available power" (and by extension,
unlimited energy).

But Wigner himself was SR.

How so? Sexual reproduction doesn't produce a replica, at least not
what I would think of as a replica. For that matter, neither does
cloning -- it produces at most an entity with a replica of one's DNA.
But the actual capabilities and attributes of a human "machine" are
determined by so much more than DNA that it would be a stretch, IMO,
even to say that mature identical twins are replicas of each other
(except in very unusual circumstances), let alone a human and a clone
that is 20 or 40 or 60 years younger.

So by
identifying the machine with the operator, we transfer the SR property of the
operator to the machine. Transisivity is a powerful theoretical tool that can
do things like prove FLT. Or prove simply that if a=b and b=c, then a=c.

Do you have any particular reason for believing that transitivity is a
property of self-replication?

Bert