Re: Goo prophylaxis (was: Hanson antiproliferation method?)

Nicholas Bostrom (
Mon, 25 Aug 1997 22:28:59 +0000

Anders Sandberg wrote:

> > Why just organic life? Why not dead organic substances, earth, etc.
> > And is there any good reason why it could not change the earth crust
> > into something with a higher binding energy?
> Energy is the problem here. While I think a workable nanite based on
> silicates could be made, the biosphere is the major source of
> high-energy chemicals on this planet. So it is the easiest target and
> most useful; eating rocks would require so much energy that the
> growth would be slow and the threat fairly minimal. And the earth's
> crust appears to be at a very deep energy minimum, I don't see how
> you could get further without tremendous amounts of energy.

Well, as long as there exist a chemical compound with a higher
binding energy than the components have in naturally occuring rock,
doesn't this mean that the reaction would be *exotherm* so that the
only energy we will need is for start-up. And even if each digestive
cycle were to take a longer time than for organic substances, this
would not matter much since we are dealing with a exponetially
increasing number of parallel processes. --This is a question to
which we should be able to have a scientific answer already today.

> > > into
> > > more of itself. It will spread with the speed of an bacterial
> > > infection, and be quite deadly.
> >
> > Why couldn't it spread much faster? Bacteria are limited to some
> > specifid kinds of hosts, the nanites could attack any organic
> > material and many inorganic ones too.
> I based this on Drexler's calculations of replication. Bacteria are
> actually quite good replicators, thermodynamics seems to place some
> limits to replication speed at a certain energy level (and you cannot
> get much more than 1000 W/m^2 on the surface of the earth).

There are two separate issues here. Your first statement was meant to
support your claim that we could hide away from bad nanites, so I
assumed you refered to the actual speed of a bacterial infections.
Your last statement says somthing not about the actual speed of
bacterial infections, but about the speed of a bacterial infection in
ideal circumstances --continuous medium, unlimited food etc. I might
agree that in those circumstances there might not be much difference
between a nano-plague and a biological plague; but what we are
talking about is the real world, and therein bacteria are quite bad
replicators in the sense that a new strand of bacteria won't cover
the whole earth in a matter of hours. What are the Drexlerian
calculations you refer to?

> > And if they were deliberately designed, they could transform
> > themself to missiles after they had eaten enough, and then swoosh
> > accross the seven sees in a very short time.
> Yes, yes. But I'm trying to discuss the immune system problem here,
> not the deliberate weapons use problem (as I pointed out in my last
> posting).

The immune system problem is part of the deliberate weapons use
problem. We want an immune system that can make us safe from a
Saddam Hussein with nanotech. If we were certain that everybody would
use nanotech in a peaceful and responsible way then we would not need
to care much about the immune problem. E. g. we could simply design
all the nanomachines to be non-evolvable. (This is done by building
them in such a way that any single one or a few mutations would lead
to a non-viable machine; only a cosmic coincidence would yield
something that can reproduce.) So I'm not sure about which problem
your are trying to solve.

> > to have the immune system quickly eliminating any
> > plagues, and it could use the fact that it has access to more energy.
> > A good design for this?
> I have been working on a system, but it is not yet written up.
> Basically, it will depend on what you want to defend.

I'm looking forward to reading about it; can you give us a spoiler?.
Is it supposed to work against designed plagues also?

> > Aha, I just thought of a third way. The independent folks could all
> > live in a virtual reality that were designed so they could do no
> > major harm. They would have no access to the real reality, which
> > would be ruled by a single entity.
> And how do you trust the independents to not figure out how to
> subvert reality in some way, or the entity to wield its power well?

My original remark was only about a possibility: if we are lucky, the
entity would benevolent and then this could work. However, now
when I come to think about it, it might be possible to have a stable
postnanotech libertarian society after all, contrary to what I
previously believed. Here is my idea:

Safe Libertarian Future:
The scenario assumes that many humans value freedom and independent
personal existence higher than anything else. When nanotechnology
approaches, they realise that if freedom is allowed in a world with
strong nanotech, then some mad person will certainly design the
doomsday virus. So they realise they have to give up on freedom. But
then some bright person comes up with the idea that all people upload
and that only a robot is left with the ability to operate in the real
world. The whole system is hardwired so that the robot only executes
instructions that have been agreed upon by the majority of the
uploads. In their virtual reality, the uploads can do anything they
want: each one has unlimited individual freedom. The only thing they
can't do in the virtual reality is to mass murder a lot of other
uploads (the virtual physics doesn't allow destructive nanomachines
to be built, for example). The uploads cannot influence the external
world either, except when a majority decision can be made. But for
many decisions, this should be feasible: e.g. colonising the galaxy
to provide more Lebensraum etc. One can even imagine refinements of
this scheme such that each individual would have his own robot that
he could to what he liked with; though this presupposes that the
robots could be built in such a way that nobody could use their robot
to do anything that would endanger the computer on which they all

This is the only way I can think of that a very nearly
completely libertarian society, without any guardian or international
government, can exist long after the arrival of strong nanotech.

Nicholas Bostrom
London School of Economics
Department of Philosphy, Logic and Scientifc Method