ABSTRACT
In this paper we define a class of mechanical systems consisting of rigid objects connected by frictional con tact linkages between surfaces. We prove that a univer sal Turing Machine (TM) can be simulated by a (uni versal) frictional mechanical system in this class. Our universal frictional mechanical system has the prop erty that it can reach a distinguished final configura tion through a sequence of legal movements if and only if the universal TM accepts the input string encoded by its initial configuration. There are two implications from this result. First, the mover’s problem is undecidable when there are frictional linkages. Second, a me chanical computer can be constructed that has the com putational power of any conventional electronic com puter and yet has only a constant number of mechanical parts.
