>CurtAdams@aol.com wrote:
>>
>> In a message dated 8/29/97 8:17:17 AM, bostrom@mail.ndirect.co.uk
(Nicholas
>> Bostrom) wrote:
>
>> >There is a difference between the three systems you mention, on the
>> >one hand, and nano self-replicator on the other. Mycoplasma
>> >genitalium, automotive vehicles and comersial software are all
>> >required to be fairly optimized.
>>
>> No, none of those are "optimized". Insofar as they are optimized, germs
and
>> commercial software are heavily optimized for miniumum design
requirements,
>> even at the cost of performance.
>
>(Fairly optimised). Germs are highly optimised, given
>certain design constraints, shaped as they are by immense selection
>pressure and short generation cycles.
Biochemistry, for any living thing, is a very sloppy thing. Suboptimal
enzymes, indirect pathways, multiple pathways, and messy genetic controls are
not merely the rule, but flat-out universal. Living things are highly
constrained by the need to proceed by small evolutionary steps, all at least
viable.
If bacteria are optimized for anything, it's for the ability to evolve
rapidly (which they do), which is for minimal design. Design is very
expensive for life, since it proceeds by very occasional mutation and then
elimination of all inferior variants.
>Cars are optimised.
In no sense. They get substantially better every year even after you
discount for technological improvement. In what sense could they possibly be
optimal at any point?
>Much
>commersial software is also fairly optimised. But you have a point
>here. There is also commersial software whose performance is not
>optimized, and in some cases it can still it can be highly
>non-trivial to design it. So if that is the relevant analogy then it
>points in the direction Carl intended it to.
Where is this optimized software? Where can I get it? My computer has been
invaded by bloatware for over a decade.
>> >To build an optimised nano
>> >self-reproducing device would be much harder than simply to make
>> >something useful that can replicate. For example, a universal Turing
>> >machine has been constructed in Conway's Life world. The entity is
>> >very big and it was hard, but nothing near a thousands of genius-year
>> >task, to do it.
>>
>> Nobody has presented a self-replicating Life system. All Conway did was
>> produce a feasibility proof, so you know it *can* be done. Actually
>> designing such a system is still considered not yet possible.
>
>Really? I thought I've heard that the Universal Turing machine was
>actually designed, with streams of gliders serving as tape etc. But I
>may be wrong, in which case I'm glad you pointed it out. Do you have
>any references?
"The Recursive Universe" by William Poundstone. It has a good layman's
description of Conway's proof, and some guesstimates of what it would take to
actually make a self-replicating Life computer (conclusion: no time soon).