researchers from MIT’s Computer Science and Artificial Intelligence Laboratory (CSAIL) have attempted to get over these growing pains with a new method: introducing magnetically reprogrammable materials that they coat different parts with — like robotic cubes — to let them self-assemble. Key to their process is a way to make these magnetic programs highly selective about what they connect with, enabling robust self-assembly into specific shapes and chosen configurations.

The soft magnetic material coating the researchers used, sourced from inexpensive refrigerator magnets, endows each of the cubes they built with a magnetic signature on each of its faces. The signatures ensure that each face is selectively attractive to only one other face from all the other cubes, in both translation and rotation. All of the cubes — which run for about 23 cents — can be magnetically programmed at a very fine resolution. Once they're tossed into a water tank (they used eight cubes for a demo), with a totally random disturbance — you could even just shake them in a box — they’ll bump into each other. If they meet the wrong mate, they'll drop off, but if they find their suitable mate, they'll attach.

“Self-assembly processes are ubiquitous in nature, leading to the incredibly complex and beautiful life we see all around us,” says Hod Lipson, the James and Sally Scapa Professor of Innovation at Columbia University, who was not involved in the paper. “But the underpinnings of self-assembly have baffled engineers: How do two proteins destined to join find each other in a soup of billions of other proteins? Lacking the answer, we have been able to self-assemble only relatively simple structures so far, and resort to top-down manufacturing for the rest. This paper goes a long way to answer this question, proposing a new way in which self-assembling building blocks can find each other. Hopefully, this will allow us to begin climbing the ladder of self-assembled complexity.”

(Via MIT)

Golden Age legend Jack Williamson wrote a great story titled The Infinite Enemy, published in Thrilling Wonder Stories in 1938, in which an alternate universe is found to contain a being comprised of metallic cubes.

Fans of early scientifiction may recall the living metal cubes from The Metal Monster, a 1920 story by Abraham Merritt.

Faster the cubes moved; faster the circle revolved; the pyramids raised themselves, stood bolt upright on their square bases; the six rolling spheres touched them, joined the spinning, and with sleight-of-hand suddenness the ring drew together; its units coalesced, cubes and pyramids and globes threading with a curious suggestion of ferment.

With the same startling abruptness there stood erect, where but a moment before they had seethed, a little figure, grotesque; a weirdly humorous, a vaguely terrifying foot-high shape, squared and angled and pointed and ANIMATE—as though a child should build from nursery blocks a fantastic shape which abruptly is filled with throbbing life.