This one should make some very very small waves. So what's next?
ATOMIC SCALES
Striking Notes of Progress on the World's Tiniest Guitar
By GEORGE JOHNSON
Published: November 9, 2003
It was weird enough when NASA's Chandra X-Ray Observatory recently came across a black hole, 250 million light years away, humming a bass note 57 octaves below middle C. Now scientists have found an accompanist to hold up the treble end.
American Institute of Physics
Scientists at Cornell University "played" a guitar just 10 millionths of a meter long by shooting laser light at its silicon "strings."
Cornell University physicists reported last week that they had used a laser beam to pluck the strings of an invisibly tiny silicon guitar just 10 millionths of a meter long. Each string of the instrument is about 50 nanometers (or billionths of a meter) wide — 100 atoms thick. Human hearing tops out at tones that vibrate at about 20,000 cycles per second. The high-pitched sound of the nanoguitar twanged forth at 40 million cycles per second, putting it 17 octaves above what human ears take for music.
Using the same kind of technology that etches the tiny wires and components onto computer chips, the researchers at Cornell's NanoScale Science and Technology Facility have also constructed a nanodrum from a crisscross diamond mesh and a nanoxylophone with tiny diamond bars.
These "nanomechanical resonant systems" demonstrate human dexterity pushed to the extreme, an attempt to revolutionize manufacturing and medicine (though perhaps not music) with artifacts as tiny and efficient as the atoms that compose the universe.
Practical applications aside, making nanothings is the ultramodern equivalent of building a ship in a bottle or carving the Lord's Prayer on a grain of rice — a feat surpassed this summer when a husband and wife team working at the Massachusetts Institute of Technology inscribed the New Testament in 24-karat gold typeface on a silicon chip five millimeters (less than one-fifth of an inch) square. Each letter was the size of a single bacterium.
The micro-Bible is enormous compared with the nanoguitar, each string of which is thousands of times thinner than a single human hair, so small that it begs the question of what one means by a "thing." Scientists can say with some confidence that a single atom does not qualify, consisting, as it does, mostly of empty space, a vast nothing separating a dense nuclear core and a shimmering periphery of electrons. Even an atom's substance — if it can be called that — is elusive, the particles hovering in a quantum state where position and momentum can be described only in terms of probability.
Put trillions of atoms together and you get something solid like a real guitar, a chunk of matter you can hold in your hands. The nanoguitar, impossibly tiny as it seems, also exhibits some of the dependable properties associated with thinginess: you can pluck it and it plays. But it hovers near the brink, at a poorly understood threshold where quantum effects begin to dominate.
When the National Nanotechnology Initiative, formed in 2001 to encourage research in this new science, used a tiny carbon needle to spell out its Web address (www.nano.gov) in letters just seven nanometers wide, it pushed even deeper into the in-between world, sometimes called the mesoscale, the murkiest of scientific frontiers.
People have, of course, been manipulating atoms all along, but only in what Ralph C. Merkle, a professor at Georgia Institute of Technology and nanotech enthusiast, called "great thundering statistical herds." Manufacturing today, he has written is "like trying to make things out of Lego blocks with boxing gloves on your hands. Yes, you can push the Lego blocks into great heaps and pile them up, but you can't really snap them together the way you'd like."
If nanomanufacturing comes of age, something as tiny as a nanodrum or nanoharp might be mass-produced for use as extremely sensitive detectors for ultra high-frequency waves. Scientists have recently demonstrated infinitesimal nanotube thermometers and nanobalances capable of weighing a single virus. All this may foreshadow a day when doctors use nanocapsules to carry medicines, a few molecules at a time, to precise locations in the body, and nanorobots to crawl through the bloodstream and repair cells.
In the meantime this all makes for good science fiction. Last year Michael Crichton published a thriller, "Prey," in which scientists develop a swarm of flying nanobots that can flock to a distant location and form a giant camera, beaming images back to the human masters. The vermin escape, of course, and being not only invisible but also artificially intelligent and very fecund, they threaten to multiply beyond control.
This is much scarier than resurrected Jurassic dinosaurs, and some scientists are already considering how to ensure that the danger never becomes real. In his newest book, "Our Final Hour: A Scientist's Warning," published earlier this year, Dr. Martin Rees, Britain's Astronomer Royal, includes berserk nanorobots among the technological threats to the future of mankind.
Other scientists think nanotech may be the savior. In addition to being very tiny, cylindrical molecules of carbon, called nanotubes, are far stronger than steel. In September, Los Alamos National Laboratory sponsored a conference on how nanotubes might be used someday to build a "space elevator" 60,000 miles high. Cheaper than firing rockets, this could provide the first great leap off the planet. With nanobots nipping at their heels, a few brave souls could escape and explore the solar system and experience first hand the music of the spheres.
