The construction of physics simulations in the alternate reality kit

The authors report on the experience gained in the construction of a bubble chamber simulation using the alternate reality kit (ARK). ARK is a graphical animated environment for creating interactive simulations constructed in Smalltalk-80 at Xerox PARC. The simulation is set into a motivating scenario-a fantasy game where the students have the goal of discovering a certain type of particle (for use in the spaceship´s drive) in order to escape from an alien planet. Playing the role of the ship´s physicist, they examine particle collisions and apply reasoning about curvature in magnetic fields, conservation of energy and of momentum, in order to identify the mass and charge of candidate particles. ARK embodies a style of object-oriented programming well suited to the construction of interactive simulations. Further the fundamental characteristic of concrete and changeable physical laws emerges automatically