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Don't let Crichton's Prey scare you--the science isn't real
A review of Michael Crichton's Prey, a novel featuring out-of-control, self-replicating nanotechnology.
Originally published on Nanotechnology
Now, Jan. 2003. Published on KurzweilAI.net Jan. 27, 2003.
Note: to explain what's wrong with the science in Prey, this
review contains spoilers.
Imagine a horror story about baseball in which the batter keeps
hitting the ball hard enough to kill the fans. The story might be
entertaining, but it's obviously unrealistic. Suppose further that
at one point in the story, the author writes about someone walking
back to the dugout after three "fouls." Does the author not know
the difference between a foul and a strike, or was he simply in
too much of a hurry to bother getting the words right? Either way,
no one could learn the rules of baseball from that story. Even if
it was mostly right, a few wrong facts make all the difference—especially
if the reader does not know which facts are wrong.
Prey contains comparable exaggerations and mistakes in science.
A scanning probe microscope and an electron microscope are basic
tools of nanotechnology, and they're not even remotely similar.
Yet Crichton confuses the two, on page 133. He also confuses piezoelectric
with photovoltaic. And he writes about a nanobot that's "one ten-billionth
of an inch in length." This is the size of a single atom, not a
whole robot. But these are simple errors; the flaws in his nanotech
run deeper.
Crichton's hypothetical nanotechnology is built in a multi-stage
process. First, bacteria produce chemicals, which are modified and
then combined to form "assemblers." The assemblers are attached
to other bacteria, which produce more chemicals that are combined
by the assemblers into the final product: a tiny, flying robot with
an onboard computer, solar cell, and other useful gizmos. Remember
that the bacteria are attached to the assemblers, not to the final
swarm-bot product. And the bacteria are not involved in the function
of the final swarm-bot (nor is the swarm-bot involved in the assembly
process). But for some unexplained reason, people infected with
the swarm-bots melt (in seconds) when splashed with a bacteria-killing
virus, which should have no effect on the swarm-bots. It makes no
sense—it was simply necessary to the story.
Even this is not the biggest problem with the science. The cornerstone
of the book is evolutionary learning and emergent behavior. Crichton's
explanations are too superficial to allow detailed criticism, but
there are a few obvious impossibilities.
For example, the swarm supposedly "learns" by reproducing itself:
the dumb swarm-bots die off, and the more effective ones survive
to reproduce. (How their program is fed back into the assemblers
is not explained.) But when the swarm first infects the humans,
it immediately begins to coexist—and even to make them look
healthier and to modify their behavior in subtle ways. The swarm
can't reproduce in humans. For one thing, there's no gallium or
arsenic for the electronics. (There's not much gallium or arsenic
lying around a desert, either.) So how did the swarm learn how to
get along with human biology and cognition? There's no way it could
have.
Crichton's introduction, "Artificial Evolution in the Twenty-first
Century," appears to be a serious attempt to warn us about the dangers
of technology that is capable of evolution. He closes by saying
that if someone manages to create evolving organisms before they
can be regulated, "... it is difficult to anticipate what the consequences
might be. That is the subject of the present novel." The scientific
explanations scattered throughout the book increase the apparent
plausibility of the story. Even the name Xymos is a clear reference
to the real-world nanotech company Zyvex.
It seems that Crichton is doing his best to scare the readers about
real-world nanotech—he wants his audience to believe that the scenario
in the novel could actually happen as described! He might succeed
in scaring people; a friend of mine who's a geneticist told me that
Jurassic Park set back public perception of genetic engineering
by a decade. This would be unfortunate, because the Prey scenario
contains so many implausibilities—and impossibilities—that in
the end, the reader will have learned nothing about the actual risks
of nanotech.
It is worth listing a few more of the exaggerations in the book.
For example, Crichton describes glass as being unsuitable for handling
chemicals: "At the molecular level, glass is like Swiss cheese,
full of holes. And of course it's a liquid, so atoms just pass right
through it." (p. 131). A little common sense shows that this is,
at best, stretching the truth. Light bulbs, vacuum thermos bottles,
and TV tubes can last for decades; they all depend on the fact that
atoms normally can't pass through glass. (Helium can make it through--in
vanishingly small amounts--but helium is completely inert.)
Another exaggeration is the idea that the swarms could coevolve
with worms in a matter of days. Even if the swarms could evolve
that quickly, the worms could not. Finally, a significant impossibility
is the idea that a swarm-bot could fit inside a synapse (p. 256).
A synapse is only a few atoms wide; the swarm-bots are hundreds
or thousands of times bigger. But without this impossibility, a
major sub-plot falls apart.
The exaggerations are not only about nanotech. Near the end of the
story, a character sets off all the fire sprinklers by melting one
of them. Despite what we've all seen in the movies, sprinkler systems
don't really work that way. Crichton's characters also explode welder's
thermite to destroy the clouds of nanobots. According to the welding
supply company I called, thermite is used for welding because it
burns hot enough to melt metal—but it does not explode. I was told
it probably wouldn't even ignite a sheet of paper a few feet away.
This is not to say that nanotech is completely safe. The possibility
of "gray goo"—self-replicating nanobots—has been discussed from
the beginning. But gray goo would be very difficult to design. It
would be far more complex than a car—probably more complex than
the Space Shuttle. General Motors recently made headlines by taking
only a few months to design a car.
It's completely implausible that a failing company could create
an evolving gray goo by re-engineering a specialized product in
a matter of weeks; this same company couldn't even solve the relatively
simple problem of keeping the swarm together in a breeze. Remember
that the swarm-bots don't directly replicate; they are built by
assemblers using bacterial chemicals. Among other tasks, the scientists
would have had to rapidly invent a way to transfer the evolved program
out of the successful swarm-bots and feed it back into the assemblers
or the bacteria to produce the next generation. This would require
a completely new set of molecular machinery.
In Crichton's stories, the scientists are mad—all but one
who moans about how "nature will find a way" and "we should not
play with things we don't understand." In the real world, it's the
other way around. We won't have nanobots for years, maybe decades,
but scientists have already written a code of practice, the "Foresight
Guidelines on Molecular Nanotechnology," that would prohibit
anything remotely like what Crichton has invented. And because evolution
doesn't work as magically as Crichton portrays it, scientists probably
wouldn't even be tempted to release evolving nanobots; in real life,
the swarm would have been destroyed almost immediately, and so would
never have had a chance to improve itself.
Nanotechnology is genuinely interesting, and in some ways even scary.
Hopefully, Preywill generate interest in the subject; reliable
information about nanotechnology is available on-line and in numerous
books. Readers of Prey should remember that it does not provide
a realistic portrayal of the technology. Many parts are impossible,
and many others are stretched beyond plausibility.
For real, scary science, read non-fiction such as The Demon
in the Freezer by Richard Preston. Smallpox isn't as trendy
as nanobots—but unlike nanobots, smallpox already exists,
and could easily be used by terrorists. Prey is not scary
science because (to be blunt) very little of it is real; those who
let themselves be scared by it might as well wear protective gear
to the next baseball game.
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