# Re: poly: New paper on Grey Goo problem

From: <hal@finney.org>
Date: Fri May 19 2000 - 14:44:28 PDT

pcm@rahul.net (Peter C. McCluskey) writes:
> Freitas assumes that if the goo consumes biomass in a way that produces a
> certain amount of heat, that all that heat will be produced in a way that
> constrains the spread of the goo by forcing it to operate at higher
> temperatures. I see three strategies which the goo might use to spread
> faster than Freitas' analysis indicates (I'm assuming that the goo is not
> attempting to avoid detection at this point):

That's a good point, active heat management by the goo could be a
big help. One thing I notice in Robert Freitas' equations is that he
is using the steady state temperature formula. Net power produced =
net power radiated, which corresponds to a particular temperature.
But during the goo's spread phase there could be considerable mass
present to act as heat sinks. For one thing, when you are talking about
global temperatures, the oceans can absorb a lot of heat (maybe not that
fast though). Even locally the goo might be able to spread itself out
so that the heating applies to large volumes of soil and biomass, keeping
the 'tech from overheating.

> I find it fairly easy to imagine that a replibot could convert 10% of the
> local biomass into more replibots, and store the remaining 90% of the
> biomass in a "stomach". This would appear to enable destruction to spread
> an order of magnitude faster than Freitas' waste heat analysis suggests,
> and I don't see any reason to expect that this is the most dangerous
> strategy that the goo could adopt. I suspect that if waste heat is a
> limiting factor for the spread of goo, that the limits need to be calculated
> based on the minimum amount of energy needed to disable the biomass
> (i.e. what is the minimum energy needed to replicate a replibot that can
> klll X kg of biomass, and what is the minimum energy required to do the
> actual killing?).

This is the kind of twisted thinking that has to be applied to
the subject. Measures, countermeasures, counter-counters, etc.
The quantitative analysis is useful in terms of establishing the broad
background of what is possible. But you have to actually play out the
game (at least on paper) to see what kinds of clever hacks are possible.

> Finally, I'm disturbed by the vague implications in the paper that detection
> is the hardest part of dealing with the standard gray goo threats.
> There are plenty of examples of somewhat similar problems (AIDS, wildfires,
> military invasion) where early detection is not enough to avoid major problems.
> While it is easy to imagine nanotech improving our ability to contain such
> threats, there is no obvious reason to be confident that the technology used
> to contain threats will improve faster than the technology used by malicious
> forces.

Right, a lot more needs to be done in order to justify this confidence.
Robert Freitas suggests that if you have an active shield deployed
and ready to go (and assuming the threat is one that you are prepared
to counter), the defenders would have advantages. They have superior
numbers, they don't need to replicate. Locally, they are the attackers,
the bad goo is on the defensive, trying to survive and grow and spread
at the same time. It's easier to destroy than create, and the bad goo
needs to create (replicate) while the good goo can just destroy (since
it is already in place with superior numbers).

It's an interesting twist on the usual way of looking at this problem,
but the problem is that it assumes that the good guys are willing to put
up with tremendous local destruction in order to cauterize the infection.
It may be a wise policy, but if it comes down to nuking Atlanta because
of a rapidly growing grey goo infestation, it will not be an easy policy
to follow.

Hal
Received on Fri May 19 14:49:00 2000

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