Several executives listen attentively to a sharp-suited sales rep making his pitch. Suddenly, a miniature car emerges from a vat of gray goop in the center of the conference table. The salesman proceeds to reshape this model using nothing more than his hands, flattening the car’s roofline and adjusting the geometry of its headlamps. Finally, he transforms the car from its initial haze gray to fire-engine red, its “atoms” twinkling in close-up with Disney-movie magic as their color changes.
Yes, it’s just a video done with special effects. But it comes from researchers at Carnegie Mellon University, in Pittsburgh, who are developing technology intended to enable not just the instant creation of complex objects—far beyond what today’s 3-D printing can achieve—but also their transfiguration on command.
Such a capability could change society even more profoundly than the Internet has. If this magical morphable matter were cheap and effective, it would allow us to send and download copies of objects as easily as we do digital documents. We could duplicate an object and then reshape it to our whims. Even if the technology turns out to be too expensive or the objects too fragile to replace conventionally manufactured goods, it might still allow people to summon up a facsimile of the thing they desire long enough to test it out, try it on, redesign it, or be entertained by it—with no more effort than it now takes to view a digital movie or play an MP3 file.
But do such wild notions bear any relation to what might actually be possible over, say, the next 50 years? To get a sense of the answer, it’s helpful first to look back a quarter century or so to the roots of this audacious concept.
In 1991, MIT computer scientists Tommaso Toffoli and Norman Margolus speculated in print about a collection of small computers arranged so that they could communicate with their immediate neighbors while carrying out computations in parallel. A large number of such computing nodes would together constitute “programmable matter,” according to Toffoli and Margolus. They were talking only about a highly parallel modular computer, one that might simulate the physics of real matter. But soon others applied this same term to a far more ambitious idea: an assembly of tiny robotic computers that could rearrange themselves to take on varying forms.
The chemistry Nobel laureate Jean-Marie Lehn independently developed related ideas even earlier, but coming from a different direction. He and others argued that chemists would use the principles of self-organization to design molecules imbued with the information they needed to spontaneously assemble themselves into complex structures. In the 1980s, Lehn began calling this “informed matter,” which would be a kind of programmable matter constructed at the atomic and molecular scale.
The last decade or so of research in nanotechnology—with its interest in “bottom-up” self-organizing systems—has lent increasing support to Lehn’s ideas. But creating molecules that can assemble into complex and even responsive forms is one thing; designing systems made from tiny computers that will reconfigure themselves into whatever you want at the push of a button is a whole other kind of challenge. For that, it’s the engineers who are now taking the lead.
The shrinking of power sources and circuitry for wireless communications now allows robots, even centimeter-size ones, to talk to one another easily. And making miniature machines that can change shape or orientation without requiring delicate moving parts is increasingly practical, thanks to the development of smart materials that respond to external stimuli by bending or expanding, for example.
In short, in the three decades since the basic ideas of programmable matter were first formulated, the technologies needed to create concrete examples have arrived and are actively being tinkered with.
Goldstein and his colleagues envision millions of cooperating robot modules, each perhaps no bigger than a dust grain, together mimicking the look and feel of just about anything. They hope that one day these smart particles—dubbed claytronics—will be able to produce a synthetic reality that you’ll be able to touch and experience without donning fancy goggles or gloves. From a lump of claytronic goop, you’ll be able to summon any prop you want: a coffee cup, a scalpel, or (as their promotional video illustrates) a model automobile to use in a sales presentation.
“Any form of programmable matter that can pass the Turing test for appearance [looking indistinguishable from the real thing] will enable an entire new way of thinking about the world,” says Goldstein. He also entertains the notion that objects built from programmable matter could be fully functional, in which case the possibilities for this technology become so limitless as to boggle the mind. “Applications like injectable surgical instruments, morphable cellphones, and 3-D interactive life-size TV are just the tip of the iceberg,” says Goldstein.
The Carnegie Mellon team calls the components of this stuff “catoms,” short for claytronic atoms, tiny spherical robots that are able to move, stick together, communicate, and compute their location in relation to others. Making them is a tall order, especially if you need millions. But Goldstein thinks it’s achievable.
Since the early 2000s, he and his fellow Pittsburgh researchers have been building modest approximations of their ultimate goal. The first prototypes were squat cylinders, each a little bigger than a D-cell battery, their edges lined with rows of electromagnets, which allowed them to stick to one another and form two-dimensional patterns. By turning various magnets on and off in sequence, the researchers could make one catom crawl around another. More recently, the team used photolithography to build cylindrical catoms about a millimeter in diameter, which can receive power, communicate, and adhere. These tiny catoms can’t yet move, but they will soon, Goldstein promises.
The key challenge is not in manufacturing the circuits but in programming the massively distributed system that will result from putting all the units together, says Goldstein. Rather than drawing up a global blueprint, the researchers hope to use a set of local rules, whereby each catom needs to know only the positions of its immediate neighbors. Properly programmed, the ensemble will then find the right configuration through an emergent process.
Some living organisms seem to work this way. The single-celled slime mold Dictyostelium discoideum, for example, aggregates into a multicellular body when under duress, without any central brain to plan its dramatic transformation or subsequent coordinated movements.
For catoms to do that, they must first be able to communicate with one another, if not also with a distant controller. The Carnegie Mellon researchers are now exploring electrostatic nearest-neighbor sensing and radio technologies for remote control.
Of course, to be practical, the repositioning of catoms needs to happen fast. Goldstein and his colleagues think that an efficient way to produce shape changes might be to fill the initial blob of catoms with lots of little voids and then shift them around to achieve the right contours. Small local movements of adjacent catoms would be sufficient to shift the cavities, and if they are allowed to bubble to the surface, the overall volume would shrink. Conversely, the material could expand by opening up pockets at the surface and engulfing them.
At MIT, the computer scientist Daniela Rus and her collaborators have a different view of how smart, sticky grains could reproduce an object. Their “smart sand” would be a heap of such grains that stick together selectively to form the target object. The unused grains would just fall away.
Like Goldstein, Rus and her colleagues have so far built only rather large prototypes—“smart pebbles”—that work in two dimensions, not three. These units are the size of sugar cubes, with built-in microprocessors and electromagnets on four faces. A set of cubes can duplicate a shape inserted into the midst of a group of them. The ones that border the target object recognize that they are next to it and send signals to a collection of other cubes elsewhere to replicate its shape.
Rus’s team hit on an ingenious way to make smart grains move, demonstrating the strategy using larger cubes they call M-blocks, which are 5 centimeters on a side. Each uses the momentum of flywheels spinning at up to 20 000 rotations per minute to roll over, climb on top of one another, and even leap through the air. When they come into contact, the blocks can be magnetically attached to form the desired configuration. At the moment, the experimenters must provide the instructions for sticking together. Their plan, though, is to develop algorithms that allow the cubes themselves to decide when they need to hook up.
The researchers’ ultimate aim is to create a system of modules the size of sand grains that can form arbitrary structures with a variety of material properties, all on demand. Shrinking today’s robotic pebbles and blocks to the submillimeter scale presents an enormous technical challenge, but it’s not unreasonable to imagine that advances in microelectromechanical systems might allow for such miniaturization a few decades from now. That would then allow someone to instantly reproduce a facsimile of just about any object—depending on what it is, maybe even one that functions as well as the original.
While the holy grail is a sea of tiny machines working together to perform such magic, Goldstein sees the basic ideas of programmable matter being applied to objects at all scales, from atoms to house bricks, or perhaps even larger. It’s almost a philosophy: a determination among today’s researchers to make their creations more intelligent, more obedient, and more sensitive, imbuing them with qualities that will eventually make them act almost like living things—like matter with a mind of its own.
This article originally appeared in print as “Infinitely Malleable Materials.”