Change and Chance

Change and Chance was the first commercial computer animation film marketed by a mainstream publisher, Penguin Books. It was a set of six films developed for the Nuffied Foundations' A-Level Physics Course, Unit 9, in 1969. Jon Ogborn (Chelsea College, University of London) and Paul Black (Physics Department, Birmingham University) developed the concept and the films were produced by Bob Hopgood using the SC4020 Microfilm recorder at the Atlas Computer Laboratory.

The films illustrated the 2nd Law of Thermodynamics (heat flows from hot to cold by chance alone). Students started by using a 6 by 6 board (a chess board with two rows blanked out in each direction) to randomly move units of energy. A move in the game represents the exchange of one quantum of energy between two atoms. Two dices gave the position where a unit of energy was to move from and a second roll of the dice indicated where it moved to.

In an hour, the students had difficult deciding whether they had reached a steady-state. Averaging over a class of 30 students gave a better impression. The solution was to repeat the game on a much larger 30 by 30 board and let it run for much longer.

The set of films produced were:

Film 1 just explained the game on a 30 by 30 board
Film 2 was similar but started with a different initial layout of the units of energy
Film 3 changed the size of the grid
Film 4 showed that observing a single cell showed the same characteristics as the set as a whole
Film 5 showed a much colder environment with only 300 instead of 900 units of energy
Film 6: the climax shows two boards, one hot and one cold. The two boards merge with units of energy randomly moving between the two boards and the two boards randomly move to the same ratio of cells with 0, 1, 2 etc units of energy illustrating the flow of heat from hot to cold.

The films were used in about 20% of UK schools for a large part of the next 20 years.

Copies of the original films are available on the Chilton website: