It's 3:30 in the afternoon on the Friday after Thanksgiving, and some 1,200 people are staring anxiously at a little boy holding a bit of string tied to the trigger of a mousetrap. Tied to the snapping arm of the trap is another string, this one connected to a small piece of wood. Eleven more mousetraps, prepared similarly and with great care, have been arranged in two rows along opposite edges of a folding table. If all goes according to plan, triggering the first mousetrap should begin a chain reaction of flying wood and string, each trap causing the next to fire in rapid succession. It worked at home and at least once during final testing--but now the bleachers and floor of Rockwell Cage are packed with onlookers, and the pressure is on.

As chief instigator and master of ceremonies for this somewhat geeky annual extravaganza organized by the MIT Museum, I feel my heart in my throat as we approach the group countdown that will start the reaction. In just a moment, hundreds of objects will become players in a drama that no one has seen before. It will last but 20 minutes or so and will never be witnessed again as a live event. Stretching out beyond this first table, with its carefully positioned mousetraps, are about 40 other tables arranged in a giant square around the center of the gym. Each is home to an unlikely masterpiece consisting of toys rescued from the attic, pieces of scrap wood from the basement, wind-up and battery-powered cars, marbles prepared to descend ramps made of every conceivable material, dominoes, video cases standing on edge so that they will act like dominoes, entire Lego collections, cups of water precariously balanced over funnels leading into yards of clear tubing, balloons in all sorts of dangerous predicaments, odd pieces of metal chosen for their sonic capacity, and duct tape--duct tape everywhere.

Hundreds of hours of careful and playful deliberations around kitchen tables or on living-room floors have resulted in a mélange of individual chain reactions that have been brought together and linked, neighbor to neighbor, with strings. Kids and parents who have brainstormed, some for weeks and others while their Thanksgiving feast was still digesting, will see their hopes either fulfilled or dashed. Parts that worked flawlessly the night before, or even in the past 30 minutes, will suddenly freeze. I have often wondered if inanimate objects can be spooked by a crowd. The most unlikely of events--a marble winding its way down the inside of a hanging spring, or a real live rabbit in a head-to-head race with a mechanical turtle--will unfold with remarkable precision. For every "hand of God" moment (when the chain reaction needs a little prompting from its creator), there will be a moment of pure grace.

The first annual chain reaction was a modest affair consisting of about 10 events snaking through the upstairs galleries and halls of the MIT Museum in 1998. It began with a simple question--what to do on the day after Thanksgiving? For many years the MIT Museum had been running community programs on this most singular of Fridays, recognizing that many families together for the holiday were looking for interesting and even educational alternatives to shopping. When I was asked to propose an activity, a community chain reaction was the first thing that came to mind. Inspired by the wonderful film The Way Things Go by the Swiss artists Peter Fischli and David Weiss, I had just created a chain reaction in my sculpture studio with a few artist friends. I was moved by the open-endedness of the structure and could see that it was a perfect context for group invention and problem solving. And a chain reaction is pure theater--it has an understandable plot punctuated by unpredictable events, gripping tension, and occasional moments of hilarity.

Now, the collective momentum propelling this year's chain reaction has reached its peak. The spectators have moved to the perimeter; video cameras are poised. After one last check to see if all is ready, I take a deep breath and announce: "Together, everyone: 5 ... 4 ... 3 ... 2 ... 1 ... GO!"

Kinetic sculptor Arthur Ganson is a former artist in residence at MIT and the inventor of the foam construction toy Toobers and Zots. See a video of the 2008 chain reaction here.