Codex Futurius: Why Gray Goo Is a Great Dud

By Amos Zeeberg (Discover Web Editor) | May 18, 2009 4:07 pm

Codex Futurius LogoThe Codex Futurius project, this blog’s never-ending quest to explore the timeless scientific questions raised by science fiction, is back—and this time we have reinforcements. The NAS’ Science and Entertainment Exchange (SEEx), a group dedicated to bringing real science into entertainment, has agreed to help us find experts who can tackle these ineffable sci-fi questions.

Our first expert-answered Codex question goes to J Storrs Hall, an independent scientist and author who’s also president of the Foresight Institute, a nanotech-oriented think tank. Thanks especially to Jennifer Ouellette, a science writer and the director of SEEx, for connecting us with Hall. Without further ado, here’s the question of the day, asked by an (imagined) big-time Hollywood director/producer who thinks getting the science right might help nail down that elusive Oscar:

“How could nanotechnology transform the world? Most importantly, how could I stop a plague of nanorobots from eating my spaceship/research facility/planet?”

Nanotechnology is going to transform the physical world in much the same way that computers and the Internet have transformed the informational world. In the long run, that means that physical things like cars and houses will see the rates of improvement that we are used to with computers. New capabilities, such as super-light, super-tough materials, will appear.

Existing capabilities that are expensive, such as photovoltaic solar cells, will become cheap enough for everyone to use. In some cases, these both will happen—it might, for example, be possible to surface the roads with photovoltaics that are tough enough to drive on but gather enough energy to power your car as it goes.

The latter half of the 20th Century was one of the most exciting times in the history of science, because it brought the solution to one of the great mysteries: the nature of life. We discovered that the almost magical properties of living things—the abilities to grow, heal, and reproduce—were because they were full of molecular machinery. (The fourth property of life, burning fuel to power useful motion, was captured in the Industrial Revolution.) Nanotechnology research and development is slowly unraveling the principles and techniques by which we will ultimately engineer new molecular machines that will be able to make high-tech products as cheaply and cleanly as biology makes potatoes.

Plagues of nanorobots, under the name of “gray goo,” were first considered in detail by the Nanotechnology Study Group at MIT in the 1980s. Their concern was that these would be mechanical bacteria. Of course, the whole Earth is covered with biological bacteria, just as small, with machinery just as molecular, as anything nanotechnology could ever make. So why was anyone worrying about a few more mechanical ones?

The main worry was that the mechanical version might be more efficient and thus more dangerous. A car can go 10 times as fast as a horse. Perhaps a mechanical bacterium could be faster, tougher, or more efficient than a biological one.

On further analysis, it turned out that the situation wasn’t that simple. Horses eat hay and grain and leaves and other naturally occurring energy sources, while cars need highly refined and expensive fuel. One reason cars are more efficient is that their “digestion” is outsourced to refineries.

Similarly, cars outsource their healing to repair shops and their reproduction to factories. They need roads and other infrastructure to be built for them. Any sensibly designed nanorobot would work the same way, for the same reason: It’s much more efficient. But that leaves the nanorobot, like the car, completely unable to go foraging in the wild and form a “plague.”

Imagine trying to build a car that ran on hay which it harvested itself, graded its own roads, made its own parts with which it repaired itself, and built new cars. Plagues of nanorobots are about as likely as plagues of hay-eating cars. And in the unlikely eventuality someone ever actually did build them, such nanorobots wouldn’t be much more efficient than bacteria, and could be controlled easily by efficient, faster, more powerful, fuel-using, non-reproducing nanomachines.  — J Storrs Hall

CATEGORIZED UNDER: Codex Futurius, Nanotech, Robots

Comments (13)

  1. Welcome aboard, Discover!

    At we’ve been a voice in the wilderness on this subject for way too long with our Science Moment!

  2. Eamon

    Gray Goo always seemed a bit ridiculous to me, cheers for ‘gelling’ the reasons why.

  3. I’m not afraid of nanotechnology considering the highly dangerous stuff going on with viruses and bacteria in research labs. We’re all only as safe as the lab techs allow. We never limit research even when it would be prudent so why start with nanos?

  4. Julian Morrison

    On the other hand, fast moving electrically powered nanotech could be arbitrarily nasty until the power goes out, and nano-engineered germs could evade the normal immune system while doing biologically-slow but still deadly harm to humans.

  5. mitchell porter

    JoSH: “in the unlikely eventuality someone ever actually did build them, such nanorobots wouldn’t be much more efficient than bacteria, and could be controlled easily by efficient, faster, more powerful, fuel-using, non-reproducing nanomachines”

    Astounding to see such complacency preached by someone who should surely know better. It is extremely likely that they will be built, they ought to be much more efficient than bacteria, and the density of “blue goo” required to police the biosphere for potential gray-goo outbreaks would itself mean the end of nature as we know it.

    Drexler’s original popular book on nanotechnology argued both that the technology could bring about radical life extension and general abundance, and also the end of the world. I get the impression that the conceptual pioneers of mechanical nanotechnology, like Drexler and Hall, have chosen with time to view the end-of-the-world dangers as overstated, perhaps because they want to keep alive that hope of a better future.

  6. Steve Liebelt

    …ummmm, excuse me, but I also seem to remember a quote from a CEO or Manager of IBM machines saying that the world will never be able to use more than about 3 or 4 computers, hahaha.
    There will obviously be 2nd generation, 3rd generation and so-on of more and more complex nanomachines, probably culminating in some kind of sellable “generic” module that can be adapted into “put your company logo here” models capable of any task. It’s all the things we can’t think of right now that will be the problems. Just wait til China gets hold of that technology, yikes, I’m not sure I want to start seeing advertising appearing on my cornflakes just before I pop them in my mouth, or my coffee cup disintegrate because I put it down for 2 minutes… :-) Oh, and you better start coating all the steel reinforcing under your skyscraper buildings in “anti-steel eating goo” before someone thinks of that possibility too…

  7. I’m more concerned about recombinant bacteria becoming invasive species (e.g. the kind they release to clean up oil spills) than anybody creating gray goo from scratch. Not to say that I think recombinant bacteria and viruses shouldn’t be used in the field – I’m a virologist and a big fan of live recombinant vaccines – but we need to make sure to build them with very good fail-safes.

    At this point in history I still think nanotechnology is a lot of sound and fury signifying very little so far. Nature is way more complicated.

  8. amphiox

    If the nanotech is designed to use carbon-based molecules and organic polymers, then it is highly unlikely that they would ever become more efficient than bacteria, simply because, over the course of 4 billion years of evolution, many of the key bacteria biochemical pathways are pretty close to maximal possible efficiency, within the restraints of the environment they evolved in, already.

    It is also quite likely that the first nanotech, at least, WILL be designed to use carbon and organic polymers because carbon chemistry is the only one we know of with the requisite versatility to produce complex nanomachines, and certainly the only one we know enough about to even begin experimenting with.

    Energy acquisition will ultimately determine the capabilities of all nanotech, good and bad. Lifeforms have already green-gooified the earth by exploiting pretty much all available chemical and solar energy sources available on this planet with near maximal efficiency, and there will be limited opportunity for nanotech to outcompete biology on these fronts. To grey-gooify the earth one would probably need to find some alternate energy source, like fusion.

  9. Rick Badman

    Nanorobots could be used to manufacture ultra-stressed crystalline molecular solid materials that would be used for flywheel storage systems for vehicles mainly. Imagine driving a flywheel-powered electric car that has two stacked units in the back to provide power for the drivetrain and four smaller units for the systems. After respinning the flywheels up to speed after maybe 15 minutes, you could drive from New York City to Chicago nonstop and take a side trip to Saint Louis after a meal during which time you would have the flywheels respun up to speed.

    If the flywheels can store over 200 watt/hours of kinetic energy per cubic inch, you may see planes using flywheels that would weigh less than the jet fuel they replace. A flight from JFK to London’s Heathrow may take less than two hours if the jet engines are electromagnetic compression-field engines that have no moving parts. As long as there is enough thrust, the electric SSTs would fly over 150,000 feet up and not need air for the engines since they would become repulsion-drive engines in the upper atmosphere. By diverting air to the nose to push it into the air, the planes could takeoff from conventional airstrips. Hover landing gear would allow the plane to land in a shorter distance even on grass since wheels wouldn’t be needed.

    Just for the fabrication of flywheels, nanorobots would be excellent construction devices.

  10. Santiago

    YES! Finally I’ve found someone voicing the same doubts I’ve had about the whole “gray goo” paranoia! I think people just seem unable to grasp just how hard it would be to miniaturize a self-replicating machine, ESPECIALLY one that had to process it’s own raw materials in any way. And some people’s fears that these things would also be able to eat *anything* just puts it beyond the impossible for me. I mean, just look at all the complicated, specialized and energy-intensive equipment we need to gather raw materials from even high-grade ores. To get things like silicon, iron and aluminium, etc in a usable form you need massive factories that often require the full electrical output of a major hydroelectricity plant!

    Basically, the only element you could conceivably use as a basis for a self-replicating nano machine would indeed be carbon. But at this point then we’d really be talking about highly efficient bacteria, with all of the problems that that entails.

    Don’t get me wrong, I think nano-machines are perfectly possible and it would be incredible if we could actually make them. A nano-assembler, being fed the required raw materials, could crank out all sorts of useful nano-machines, but at no point would we be at risk of being taken over by a single stray self-replicator.

  11. I’m finding the whole ‘gray goo’ concept hard to take in at the moment, i’ve done my fair share of research.

    This has made it that much easier; thanks!


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