Re: >Techno-Optimism v Pessimism

From: Robert Bradbury (
Date: Tue Jan 18 2000 - 18:33:31 MST

On Tue, 18 Jan 2000, David Crookes, commenting on my graphs wrote:

> What are the Y axis variables.

It depends on how I put them together, but generally X is "year"
and Y is scale of micro/nano-assembly, Instructions/CPU, memory
density, etc. The really interesting ones are growth in wealth
or matter manipulation capacity where you go off the scale in days.

> I presume you have CPU & memory storage graphs but I'd be interested
> in seeing what else.

The really interesting ones are self-assembling self-replication
times. *Fundamental Question*: Assuming you have the feedstock,
what are the limits to "physical growth". You think that question
would have been answered by science now. Not to my knowledge.
Eric does a lot of hand waving between the replication time
for a nanoassembler and the replication time of a 1kg assembler
system in Nanosystems. One of the recent papers by Josh seems
to hint that Eric is rather conservative. Other comments by
Robert Freitas seem to lead me to that conclusion as well.

For a real world example -- ask yourself this -- If you have
three "molecules" and a genetic program for them, i.e. the DNA for
the genes of RNA and DNA polymerases and the ribosome subcomponents
and one of each of those"machines" to implement the cycle:
  DNA -> RNA; RNA -> Protein; Protein makes more DNA & RNA
how fast can that system double itself (given unlimited energy
and material resources)? I haven't worked it out yet, but my
brief investigation into the limiting factors (rates of transcription)
suggests that it doubles in very short periods (probably minutes).
And this is for a system that nature did not design to be highly
optimized for "reproduction".

> Would you be willing to post them?

I do intend to get around to organizing and HTMLizing some of my
work sometime this year. Of course I'll let the list know.
If you don't see it in a few months, lean on me a bit, I tend to be
demand driven.


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