Re: Goo prophylaxis

Nicholas Bostrom (
Tue, 26 Aug 1997 12:25:43 +0000

Anders Sandberg writes:

[Eliezer Yudkowsky wrote:]
> > How much time would it take for a nanomachine to construct a nuclear weapon?
> > I think we can assume that nano is at least as destructive as nuke.
> Numbers, please. It is easy to claim something like this, but is it
> really true?
> Building a nuke: you need around 10 kilograms of uranium 235 (or whatever
> isotope it was). There is around 2 grams uranium / tonne in the crust of the
> earth, of which 0.72% is U235, so to get 10 kg you need to process around
> 7000 tonnes of crust. I'm not sure how much energy is required to reduce
> the UO2 to pure U, but it is a noticeable amount (are there a chemist
> in the house?). Assuming the nanites cover a large patch with solar
> collectors, they can get around 500 W/m^2, which has to cover their
> replication, search through the crust, reduction, isotope separation and return
> to the "base"; how much energy this is is a bit hard to tell right now
> (it is 1.30 in the morning here :-), but it looks like it will take
> a while for the bomb-mold to blow up. A wild guess would be around a
> week.

Even so, the nanites could cover continents with construction sites
so you couldn't bomd them all out. Dynamite should be much easier and
serve just as well.

> Doing the same work as a nuke with nanites (i.e. disassembling everything
> within a few hundred meters and blasting everything within a few kilometers)
> is rather tricky, since it is extremely energy intensive. You need plenty
> of energy to do the disassembly (essentially you have to break most molecular
> bonds)

As I asked in an ealier posing, wouldn't you *gain* energy if you
then reassemble them to compounds with higher binding energy?

> it is IMHO clear that we should not be overly worried about
> nano-built nuclear weapons but rather nano-ebola.

I think Eliezer was trying to establish a lower buond on the
destructive capability. The reason I begun to talk about dynamite was
that it would mean that we can be certain that the bunkers you
suggested wouldn't work agains a designed killer nanite.

> > Our immune systems are unimaginably more sophisticated than a virus or a
> > bacterium, using controlled evolution to combat natural evolution. And yet we
> > still suffer from colds and diseases. The only reason that the viruses
> > haven't killed us outright is that it isn't good strategy.
> Exactly. So the major question is: is it possible to create a nanite
> infection that is deadly (or subtle) enough to wipe out all competition?
> Don't reflexively answer 'yes' to it, try to give a considered
> answer of why it is likely (or why not).

Yes, if it is the first nanite infection, there would be no
competition to compete with! (Biological organisms compete in a lower

> > It is easier to destroy than create!
> You repeat this as a mantra. And of course you have the second law of
> thermodynamics on your side. The problem is that you do not attempt to
> make quantitative comparisions between the strengths of different systems,
> and instead rely on plausible-sounding arguments. That is definitely
> *not* a good strategy if you are trying to discuss something important
> where we do need a well planned policy.

I agree. We need to try to spell out arguments carefully.

> let's try a simple sketch to see how easy it is to vanquish a designed
> immune system:

That's the spirit we like on this list!

> The body is surrounded by an inert skin (say diamond); attempts to
> physically breach it can be detected from the inside and the surrounding
> region sealed. The rest of the organism (could be a transhuman, factory
> or a city) is compartmentalized with similar walls; infected sections
> can be isolated.

Well, if the organism is in a free environment, then the plague would
attack all parts of the skin simultaneously. The whole skin would
thus have to be shed. The plague would immediately attack again, and
soon the organism would run out of resources. Alternatively, the
plague could build explosives and blast your organism. So it seems
that your organism could not be a transhuman, factory or a city, but
would have to be the whole planet.

> Immune devices move around, interrogating "cells"
> (subsystems) by comparing their surface markings with allowed types
> (this list can be kept secret from someone who disassembles a device
> by using a trapdoor function), and occasionally disassembling the
> cell to check its innards. Other immune devices check the general
> activity, looking for deviations from the normal state

And if the organism is the whole planet, then this would of course be
equivalent to a totalitarian state. (Deviations from the normal
state= activities of some individual that the state does not approve
of, even if that individual hasn't harmed anybody yet.)

It is still interesting to see where this will lead. This thread
continues to produce an extraordinary number of interesting comments!
:-) :-) :-)
Nicholas Bostrom
London School of Economics
Department of Philosphy, Logic and Scientifc Method