[ExI] [Open Manufacturing] Re: Power sats and the industrial development of space (was global waming again)

Bryan Bishop kanzure at gmail.com
Tue Mar 24 22:13:35 UTC 2009

On Tue, Mar 24, 2009 at 1:50 PM, Jeff Davis <jrd1415 at gmail.com> wrote:
> On Tue, Mar 24, 2009 at 1:20 AM, Bryan Bishop <kanzure at gmail.com> wrote:
>> On Tue, Mar 24, 2009 at 1:37 AM, Jeff Davis <jrd1415 at gmail.com> wrote:
>>> Sure be nice to know how much that mini combine would weigh.  Yo,
>>> Bryan, care to comment?  What basic tool set would my thousand
>>> hamster-sized robots need in order to process the raw materials, build
>>> the moon base, and make more bots?  Minimum mass; lunar regolith
>>> starting materials;...
>> That really depends on the context.
> Absolutely.  I was a bit coy with you.  The design space --137
> practical multivalued replicator design properties which may be
> grouped into 12 primary design dimensions in four principal categories
> :
> http://www.molecularassembler.com/KSRM/Figures/5.5.JPG
> presents a challenge that I'm fond of comparing to the Gordian knot.
> Remember how Alexander solved that problem?  Took out his sword and
> chopped it up.  Refused to be constrained by imposed definitions of
> impossibility.  That's the view I've adopted.  Evaluating the design
> space for the "best" approach, and then working up a design -- these
> are paralyzing pre-conditions.  Screw that.  Go pure ad hoc.  Pick an
> approach and go for it.  Let the chips fall where they may.  This is a
> winner take all venture.  That's all as in ALL.

Under what authority were those 137 properties designed? This reeks of
bullshitting. There's no master data set of all possible manufacturing
processes. And I have yet to find a partial data set of said
manufacturing processes (except perhaps the recent one I sent to the
list re: thermodynamic analyses), which would be somewhat useful in a
slightly different way. But anyway, there are certain properties of
self-replication that need to be well-defined, otherwise you're just
flinging poo like a monkey. This is why Freitas put a significant
amount of time thinking about 'vitamins'.


Why is an ad hoc design not as interesting- or indeed why have all of
the current ad hoc designed systems so completely failed to do
self-replication? By picking up a single pebble, or grain of sand on
the beach, you do not completely isolate the tides and the geological
processes that led to that grain of sand; similarly, if you buy a part
from the hardware store, you probably know very little about what into
making that part. By just randomly starting at some place, such as 'at
this part', means that you- ideally- are going to go traverse the
linear chain of processes that made that part; however, in most cases
these are commercial businesses and aren't too happy about a fellow
reverse engineering every square inch of their facilities. In some
cases, there are craftsmen who still make parts by hand, who are still
interested in community involvement, and perhaps there are still
handcrafted versions of every item that we see out there, and then
perhaps it would be a legitimate and comprehensive task to go find all
of those skillsmen and learn their trade for each item that they make?
That's an intriguing prospect, but there's no guarantee that you're
ever going to be able to find those people, let alone the subset of
those people that might be working with manufacturing processes that
would be useful in self-replication, and whether or not the time that
you invest will at all reveal to you in a useful order the set of
processes that could become a comprehensive whole of a
self-replicating system. That's the thing- it either self-replicates
or it doesn't, none of this "it almost self-replicates!" nonsense. How
could it be partially doing something that it's not doing? How can you
have a 36% of a 'self'? It's a binary thing- it's either within the
limits of uncertainty or it's not, and if it by definition is
'partial' then it's not going to be near any of the error bars of the
target. I don't know if we've ever had our pow-wow here on the list
about whether or not partial self-replication is worth our time, or
the different thinking going into that, so if anyone wants to raise up
a few comments, that'd be neat.

Anywho, time to quote Freitas.

Consider, for example, the problem of parts closure. Imagine that the
entire factory and all of its machines are broken down into their
component parts. If the original factory cannot fabricate every one of
these items, then parts closure does not exist and the system is not
fully self-replicating .


The fraction of total necessary resources that must be supplied by
some external agency has been dubbed the "Tukey Ratio" (Heer, 1980).
Originally intended simply as an informal measure of basic materials
closure, the most logical form of the Tukey Ratio is computed by
dividing the mass of the external supplies per unit time interval by
the total mass of all inputs necessary to achieve self-replication.
(This is actually the inverse of the original version of the ratio.)
In a fully self-replicating system with no external inputs, the Tukey
Ratio thus would be zero (0%).

It has been pointed out that if a system is "truly isolated in the
thermodynamic sense and also perhaps in a more absolute sense (no
exchange of information with the environment) then it cannot be
self-replicating without violating the laws of thermodynamics"
(Heer,1980). While this is true, it should be noted that a system
which achieves complete "closure" is not "closed" or "isolated" in the
classical sense. Materials, energy, and information still flow into
the system which is thermodynamically "open"; these flows are of
indigenous origin and may be managed autonomously by the SRS itself
without need for direct human intervention.

Closure theory. For replicating machine systems, complete closure is
theoretically quite plausible; no fundamental or logical
impossibilities have yet been identified. Indeed, in many areas
automata theory already provides relatively unambiguous conclusions.
For example, the theoretical capability of machines to perform
"universal computation" and "universal construction" can be
demonstrated with mathematical rigor (Turing, 1936; von Neumann, 1966;
see also sec. 5.2), so parts assembly closure is certainly
theoretically possible.

An approach to the problem of closure in real engineering-systems is
to begin with the issue of parts closure by asking the question: can a
set of machines produce all of its elements? If the manufacture of
each part requires, on average, the addition of >1 new parts to
product it, then an infinite number of parts are required in the
initial system and complete closure cannot be achieved. On the other
hand, if the mean number of new parts per original part is <1, then
the design sequence converges to some finite ensemble of elements and
bounded replication becomes possible.

The central theoretical issue is: can a real machine system itself
produce and assemble all the kinds of parts of which it is comprised?
In our generalized terrestrial industrial economy manned by humans the
answer clearly is yes, since "the set of machines which make all other
machines is a subset of the set of all machines" (Freitas et
al.,1981). In space a few percent of total system mass could feasibly
be supplied from Earth-based manufacturers as "vitamin parts."
Alternatively, the system could be designed with components of very
limited complexity (Heer, 1980). The minimum size of a self-sufficient
"machine economy" remains unknown.

That last part might be a hint towards future (as in, current- as in
stuff you can do today) analyses, towards figuring out the minimum
'size' of a self-sufficient 'machine economy'. Anyway, reprap went
(started!) pure ad-hoc, wanted to do self-replication, and then lied
to the NY Times and so on. I'm still upset about that I guess. In
truth it began as a goo squirter- but where did the idea of
self-replication jump in? Does anyone know the history of this
specifically? Now, you could legitimately claim that I have not seen
an ad hoc design process for a non-goo-squirting self-replicating
machine (that may or may not involve goo squirting in it at some
point, of course, just not "let's build a goo squirter and call it
self-replicating")- and so if you showed me plans for an ad hoc design
process for a self-replicating machine, I'd definitely look over it
and put a lot of thinks into it.

> As a race to the next stage of industrial production, it can easily
> boil down to the first one out of the starting blocks.  Get enough of
> a lead before the rest of the world figures out the implications, and
> they'll never catch up.  And, regarding design choices, if you can
> generate enough excitement in the global internet-connected "game
> space",  you can promote competition among teams whose members have
> chosen different design approaches.

I am not against competition, but I would express caution when
comparing different design decisions, because some decisions are made
for totally different reasons, like in the case of reprap- it's not
really about replication, for instance- and comparing it to somebody
who is designing an artificial synthetic organic lifeform chemistry
out of, say, silicon. So while I'm not going to get worked up about
the existence of alternative designs, I'm going to very clearly make a
big stink when you're not actually working on self-replication, or
when you make erroneous claims about the capabilities of your machine
:-). A friendly big stink, of course, but still, a stink. I don't know
if you're referring to the SKDB design methodology for
self-replication when you say evaluating a solution space for a 'best'
design. There's a difference between evaluating the possibility space
for *actual* designs versus selecting from those actual designs and
finding the best among them. I agree that finding the 'best' among
them at this point is a non-starter-- but at this point, we don't even
have preliminary designs for self-replicating systems, just a lot of

- Bryan
1 512 203 0507

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