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*Co.Design*

# Lego Calculator Can Do Anything Your MacBook Can

A crew of geeks in the Netherlands used Lego to make a Turing Machine—the theoretical construct that birthed the modern computer.

Everyone reading this post can thank Alan Turing for the privilege. Turing is widely considered the father of computer science: he cracked Nazi crypto-codes during World War II and helped design the first working computer. But before all that, at the tender age of 24, Turing had the central theoretical insight behind every shiny gadget you know and love: a hypothetical, idealized computer called a Turing Machine. To celebrate the 100th anniversary of Turing’s birth, a team of geeks from the Netherlands decided to explain to the world just what the heck a Turing machine is—by designing and building one of out Lego. Check it out:

A Turing machine is a computer boiled down to its purest, simplest form. It’s also imaginary. That was the point: Turing conceived of his eponymous machine before any actual computers existed, as a thought experiment that would help illuminate just what, exactly, a computer could do. It turns out that all you need to "compute" something is a paper tape divided into cells; a "write head" that can place marks on the tape or remove them, one cell at a time; and a table of instructions for how the "write head" should move backwards or forwards along the tape. Turing proved that if enough time and tape were available, this "machine" could handle *any* computational task thrown at it.

In plain English, this means that anything and everything that modern computers can do—from playing back video and sending tweets to analyzing stock markets and autopiloting spacecraft—can be done by Turing’s paper-powered gewgaw. (Technically, it’s the reverse: the Turing machine proved that real-world computers would be able to do all those amazing things, even before anyone was able to build them.)

Turing machines are simple, but still hard to visualize for most laypeople. That’s why Davy Landman and Jeroen van den Bos, two computer-science PhD students in the Netherlands, decided to build one. "We hoped that having a real working computer built from Lego would make the theory behind it more approachable," van der Bos tells Co.Design. "Lego is one of the few toys that everybody knows, so this would make it recognizable to a very large group of people. We felt this was important because our goal was to show that the concepts underlying all computers are not extremely complicated and can be understood by anyone."

The Lego Turing Machine took about 60 hours to design and build. Instead of a paper tape and written marks, it uses 32 black Lego Angle Connectors as switches that a robot arm flips up or down. Why 32? "It was just the total amount of Angle Connectors that we had lying around," van der Bos says. "Also, for demonstration purposes, it’s long enough—calculating 2+2 takes about five minutes and requires ten switches and 33 instructions."

Watching the Lego Turing Machine grind out answers to simple arithmetic problems by flipping single switches back and forth may not seem like the most thrilling visual spectacle in the world. But when you consider that your laptop is doing the exact same thing, millions of times every second, the (yes, I’ll use the word) *awesome* power of the Turing Machine becomes a bit clearer. Whether it’s displaying retina-quality screen imagery at 30 frames per second, running Angry Birds, or parsing the contents of this blog post, everything and anything your computer can do—and ever will do—all comes down to the same thing in the end: flipping little switches back and forth, back and forth.

Van der Bos and his collaborators intend to release building instructions for their model so that anyone can create a Lego Turing Machine of their own. In the meantime, take a few minutes, watch the video, and appreciate everything that Alan Turing’s big idea has made possible.