Daily Archives: November 22, 2010

3-body problem

On the 3-body problem:

The program is a simulation of the 3-body problem: to find the trajectory of three planets through space. But why is this a problem? Well, let us look at some simpler versions of the problem to see why anyone cares about this.

The 1-body problem is simple. Newton’s First Law tells us all about it: An object at rest remains at rest, and an object in motion remains in motion, unless acted upon by an outside force.

The 2-body problem is simple enough to be solved with some calculus and analytic geometry–for example, if the two bodies are the sun and the earth, the earth orbits around the sun in an elliptical orbit while the sun sits almost idle at the focus of the orbit.

Because each body in the 3-body problem is being pulled by two other bodies, the motion of the bodies becomes much more complicated. Because of this, it is much more difficult to predict the positions of the bodies at some given time.

When you have 1 or 2 bodies, it’s easy to calculate the motion of the bodies. Once you get to 3 bodies, everything is just chaos. It becomes very difficult to predict what will happen.

I think this is a good analogy for coordinating things with people. I encountered this with trying to set up internet with AT&T. All they needed to do was get into the main box for the apartment building and activate my phone line. This required setting things up between me and a giant corporate bureaucracy. This was frustrating enough, but it only involved two bodies. However, to actually get into this box, it had to be unlocked. That meant somebody who worked at the apartment complex had to be around to open it. Once a third body is introduced, it becomes infinitely more difficult to coordinate. Plus, it’s not like I could pick a time for everyone. The people in the office are just in the office, and AT&T schedules 4-hour blocks, and they can’t even get in during those blocks. I’m convinced that the only way to get three people to coordinate is to have a little luck.

This is why Richard and I made Larry Whitman a two-person project. Once a third person is introduced, it becomes damn near impossible to coordinate schedules. When one person has something come up (as inevitably happens in life), it stops the project for everyone. It’s also hard to find a free day for everyone in the first place. Two people might have Thursday nights free, but Thursday night is always the night the third person has been poker night for two years. Now, this doesn’t mean Richard and I finished the project in a timely manner, but at least the thing got done. With three people, I’m sure the first episode would never have been produced.

Obviously, there are organizations and events that exist yet require three or more people. How is this even possible? I’ll explore that later. (Luck is one factor because most of these endeavors fail miserably.)