On Thu, 10 Nov 1994, Barbara Weitbrecht, Smithsonian wrote: > > Subject: Re: galton quincunx > > Marvelous word, "quincunx". Those of you who have been putting > off a trip to the dictionary to look it up should delay no longer. > > > The Boston Children's Museum had (years ago) a device that dropped > > the balls and resulted in the bell shaped curve. Try them. > > So did the wonderful Mathematics exhibit in the Museum of Science > and Industry in Los Angeles. That gallery was one of my favorite > museum spaces when I was a somewhat nerdy child in the L.A. basin. > It is still there, I wonder? IBM's 'MATHEMATICA' at the Museum of Science in Boston still has a Galton ball machine. I think I recall seeing one at the Tech Museum in San Jose. These devices gave me some insight into Chaotic Dynamics when fractals hit the fan in '84 - '88. The Gaussian distribution in the exhibit is an emergent property. It is generated by the nonlinear "decisions" that come about when a ball falls to the left or right of a pin. And the whole exhibit acts as a powerful amplifier of variation in initial conditions. I wonder how much of the ball distribution comes about by a Gaussian distribution of velocities in the incoming balls (and in thermal and sound vibration in the pins?) Maybe the curve arises because the noise and vibration in the exhibit guarantee that the balls will make random decisions when they strike the pins. If precision initial conditions could be created, and if the pins were vibrationally isolated from the exhibit structure, would ALL balls start to take the same path? Or is the amplification so great that quantum uncertainty in the balls and pins would still create a bell shaped curve? Or maybe it's just because the balls aren't perfectly round and polished... .....................uuuu / oo \ uuuu........,............................. William Beaty voice:206-781-3320 bbs:206-789-0775 cserv:71241,3623 EE/Programmer/Science exhibit designer http://www.eskimo.com/~billb/ Seattle, WA 98117 [log in to unmask] WEIRD SCIENCE web page