Fun fiction, yes, but real-life researchers now are crossing the frontiers of a new technology -- called molecular nanotechnology -- that might one day result in devices even more bizarre than replicators and self-constructing skyscrapers.
For now, nanotechnology devices are strictly theoretical. But by fiddling with atoms and molecules -- the basic building blocks of all matter in the universe -- scientists hope to open doors to a new world of ultra-strong materials, machines no bigger than a few atoms and self-assembling systems capable of linking molecular arms to create everything from dust-sized computers to spacecraft that weigh no more than the family car.
Eventually, nanotechnology could result in molecular robots that could be injected into a human body and programmed to seek out and destroy specific cancer cells, blast through plaque in arteries or attack invading viruses or bacteria.
''This is going to change the world in a way that we haven't seen since we learned to talk and write,'' said Jim Von Ehr, founder and financial backer of Zyvex, a Richardson, Texas, company trying to make the world's first nanotechnology assembler.
When molecular nanotechnology advocates first met in Palo Alto in 1993 to share research results, much of the larger scientific community scoffed at their wild dreams of a human-controlled nanoworld (the prefix ''nano'' refers to one-billionth of one meter, about the length of five carbon atoms strung together).
At the time, only a few dozen scientists were willing to publicly admit an interest in the field; their research work often was described subtly as chemistry experiments or biology projects.
Even the most optimistic among them guessed that practical nanotechnology applications were at least a century away. Some suspected that real nanotechnology might never be achieved.
This month nearly 350 researchers, many of them proud to call themselves nanotechnologists, crowded into a Palo Alto hotel for the fifth annual Foresight Institute Molecular Nanotechnology conference. While still careful about promising too much, participants were giddy with the coming possibilities.
''The proper unit of measure for 'when' is decades: Maybe half of one, maybe two or three. If we really run into trouble then 10 or 12,'' said Al Globus, a NASA/Ames computer scientist whose team's theoretical work in the field won the institute's highest honor this year.
''The number of decades is strongly a function of the amount of work we put into this. Perhaps a better answer to the question of 'when' is: Just before we colonize the solar system.''
While his audience at the conference laughed at that point, Globus is quite serious about it. Nanotechnology, he said, will open access to space as no previous technology has been able to do.
Why? Part of the answer lies in the mind-boggling strength of a crystalline form of carbon -- nicknamed the ''buckyball'' -- discovered in 1985 by Rice University chemist Richard Smalley, who last year shared the Nobel Prize for his discovery.
Each buckyball -- formally called a ''buckminsterfullerene'' to honor futurist R. Buckminster Fuller, whose geodesic domes the molecule resembles -- contains 60 carbon atoms linked to form a shape similar to a soccer ball. It is only the third molecular form of carbon known to humanity; the other two are diamond and graphite, the form of carbon found in a pencil tip.
In 1991, researchers figured out how to get buckyballs to hook themselves together into long tubes that look like rolled chicken wire and are appropriately called buckytubes, or nanotubes.
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''You can do anything you damn well want to with these tubes and they'll just keep on truckin,' '' Smalley told colleagues at the conference. ''Whatever you do . . . when you let it go, it goes right back to the way it was.''
The important difference between nanotubes and other types of fibrous material is that nanotubes are perfect in a molecular sense. There are no imperfections threaded through the material that can cause weakness or instability. If scientists can figure out how to manufacture nanotubes in sufficient quantity -- as of now, one laboratory can produce 10 grams every 24 hours -- nanotube fibers could one day be used to make ultralight bulletproof vests, Smalley speculates.
Alex Zettl, a physics professor at the University of California-Berkeley, has been experimenting with the electrical properties of nanotubes, which he believes may be one of the most perfect conductors yet discovered.
He speculates that nanotubes could be used to make atomically precise electronic circuitry. An early use might be in the development of high-quality flat-panel displays -- slimmed-down cousins of the bulky computer monitors and television sets in use today.
Nanotubes could be ''the supermaterial of the next century,'' he said. ''That might not be overstating it.''
Still, Globus and other theoreticians go a step beyond nanotubes: If scientists can develop other atomically precise materials, engineers could use them to design spacecraft as strong as the existing space shuttle but no heavier than a car.
''Today it costs $10,000 a pound to launch (a payload) into orbit,'' Globus said. ''NASA's goal is to get that down to $200 or so a pound by 2020. That's not an impossible goal.''
One theorist took existing spacecraft designs, removed the titanium involved in the construction and made a new design using the strongest material that could be made if only it could be built perfectly at the atomic level, Globus said. Assuming that material could be made cheaply -- and nanotechnologists believe that once they figure out how to do it, such manufacturing would be very inexpensive -- the resulting theoretical spacecraft would cost about $60,000, he said, ''about the cost of a nice Mercedes.''
''If you can buy a $60,000 vehicle and stuff your family inside for a little field trip into space, then colonization will happen,'' he said.
There is that first hurdle, of course: Scientists must figure out how to move molecules and atoms precisely into place, and then persuade them to stick together in exactly the order required.
''Today's manufacturing methods are very crude at the molecular level,'' said Ralph Merkle, a nanotechnology theorist at Xerox Palo Alto Research Center. ''Casting, grinding, milling and even lithography move atoms in great thundering statistical herds. It's like trying to make things out of Legos with boxing gloves on your hands. You can push the blocks into great heaps and pile them up, but you can't really snap them together the way you'd like.
''In the future, nanotechnology will let us take off the boxing gloves,'' he added.
Strong, cheap, lightweight materials would be just the first leg of the nanotechnology journey, he said. Researchers hope to harness existing chemical and biological forces to persuade the newly formed molecular material to repeat its own manufacturing process again and again and again.
One approach might involve synthesizing the basic blueprint of life -- DNA -- to form a scaffold onto which other materials could be bound.
Nadrian Seeman, a New York University biochemist, recently managed to create just such an experimental scaffold. Other researchers are working feverishly to develop methods for getting enzymes and other materials to adhere to specific locations along the DNA strands within that scaffold.
There is an added advantage to using DNA: Scientists know how to replicate it in the laboratory. So if researchers can build one scaffold, in theory anyway they should be able to persuade the DNA to make more scaffolds for them. Farfetched? Not really, Merkle insisted.
''Before we could fly, we knew that heavier-than-air flight was possible because we could see birds doing it every day,'' Merkle said. ''We know that rapid, cheap self-replication can be done because we see it happening in agricultural products every day. We have a biological example of how to achieve this.''
One initial self-replicating nanodevice likely would be the elusive assembler that Von Ehr's company is pursuing. Essentially an atomic-scale robot, this assembler would accomplish two things: making more of itself as well as performing a specific function, such as pulling a few particular molecules together into a preprogrammed pattern.
Assemblers could one day become part of the very fabric of a material, creating theoretical ''smart matter'' that could detect and repair flaws within itself -- hence Gibson's ''Idoru'' self-assembling skyscrapers. Bridges could rearrange themselves to handle varying stress points. The molecules in airplane wings could flex automatically to adjust to changing air pressure.
Ultimately, researchers hope, assemblers might be programmed to self-replicate, then seek out certain crucial molecules in their environment, bond those molecules together and hand over the finished product -- hence the all-powerful replicators of ''Star Trek.''
Von Ehr warns, however, of a possible darker side to nanotechnology.
''If Saddam Hussein had nanotechnology, he could make a lot of nasty things,'' he said. ''My big hope is that the good guys get there first. We can really make a change for the better in the world at large if we can develop this technology for positive uses and then stay ahead of the bad guys and anything they try to do with it.''
Chris Peterson, executive director of the Foresight Institute in Palo Alto, which exists to educate the public about the potential of nanotechnology, said researchers already have begun discussing such issues.
''How do you head off abuse of nanotechnology? That's really hard to answer until we know what is possible,'' she said. ''We don't even have the terms to discuss this yet, but I would think we need to set up some kind of nanotechnology immune system that could fight off invading nanotechnology viruses.''
Such impromptu language hints at what tomorrow's nanotechnology might be like.
''We already have a nanotechnological system that works. We call it life,'' Seeman said. ''We can take the same principles that biology has already given us and go beyond that.''