π

My wife has been trying to teach some elementary school kids about perimeter and circumference. For circumference you need our old friend π (Pi): 3.14159... To illustrate this concept we came up with a little demonstration:

• Take a can and make a mark on the rim. Make sure the can has a rim on the top and bottom. Otherwise it won't roll straight.
• Place the can on its side on a sheet of paper with the mark at the bottom.
• Make a corresponding mark on the paper.
• Roll the can along for one revolution until the mark is at the bottom again.
• Make another mark on the paper.
• Measure the distance between the two marks.
• Measure the diameter of the can.
• Divide.

It worked out okay. They came up answers around 3.2 on their calculators. Considering their age and dexterity and the precision of their instruments, I think they did okay. One web site I enjoy is Rocketboom.com. One video has the host(ess?) reciting the first billion or so digits of Pi:  

All this talk about Pi got me to thinking. What if Pi isn't really an infinitely long number? What if it really stops after, say, ten digits or so? Would anyone be able to tell the difference? I know mathematicians would argue that no, no, no, it must go into infinity, but all they really have is their precious theories. I mean they don't have any real concrete evidence, do they? And what if their theories are wrong? Who would know? Okay, I'm probably all wrong about this. I sure they have a whole set of interlocking explanations that tie back to the real world.