### Physical programming

Physical programming is an overlap between **algorithm implementation**, **science discovery**, and **performance art **using groups of people as calculational tools. The first iteration of physical programming involves four potential projects:

1. Calculating pi: Buffon’s needle

Have people lie flat and straight at random positions in a room and video from above. Superimpose parallel lines on the video and use Buffon’s needle technique to calculate pi.

Expected result: A numerical estimate of pi.

2. Showing interference of waves

Have a set of ropes coming from two poles. The ropes are all integer multiples of some “wavelength” in length. Each person chooses a rope at random from each pole and moves to a place where both the ropes are at full extension. Then they wait there while the next person repeats the process. The people will build up a diffraction pattern.

Expected result: A clumping of people at interference maxima.

3. Ising spin model of ferromagnetism

Have a large number of people stand in a two-dimensional array. Each has a die. To initialize, every rolls their die and faces forward if they roll 1-3 or backward if they roll 4-6. Then periodically ring a bell to let people know to update their state. At the time of the bell ring, they change direction according to the following algorithm. Among the four people who are ahead, behind, left and right of them, count the number of people facing the opposite way. Then roll the die. If they roll less or equal to that count, they turn to face the opposite way. Otherwise, they stay facing the same way.

Expected result: Magnetic domains are established and evolve until eventually the lowest energy state of all people facing the same way is reached.

4. Laser boson condensation

Have a group of people start walking from a random position either one direction or another at a constant speed between two walls (mirrors). If you are about to bump into somebody, flip a coin. If you get heads, change your motion to walk in step with them. If you get tails, continue on as before. If you get to a wall, just turn around and continue back the other way.

Expected result: In time, everybody will be walking in step, just like the photons in a laser are in phase.

This conceptual proposal won the award for best integration of arts and science at the San Francisco Science Hack Day 2014.