The work Bispazio instable is the most emblematic of all the research on the theme of instability and the program. It was first realized in 1962 after many exchanges with the members of the N Group on the problems of "visibility of the program".The first Bispazio instable was created for the collective exhibition Arte Programmata in May 1962 (created by Bruno Munari and Giorgio Soavi) and exhibited in Milan in the Galleria Vittorio Emanuele, at the headquarters of the Olivetti store. That the prototype was then sold to the Olivetti collection at the end of the performances (Venice, Rome, Trieste, Düsseldorf, London)
Bispazio instable is a wooden structure with front glass closures that contain small spheres of white and red celluloid placed inside two communicating spaces delimited by crystals. The central diaphragm has three circular holes that allow the passage of one sphere at a time.
At the beginning, the two spaces each contain spheres of the same color, a situation that they will not reach later on the first manipulations. By moving the object, in fact, the spheres migrate from one space to another, forming a composition of stochastic configurations that are always new.
In the unstable Bispace, the quantity of spheres in the two compartments changes constantly and the two accumulations compose configurations that are always different. In this case, as in others that deal with instability, the following reasoning is valid Chiggio was then at the forefront of the calculation of probabilities and stochastic results of Markov chains.