A universe for molecular modeling of self-replication

An abstract two-dimensional universe is presented, in which self-replication can be modeled and studied by computer simulation. Two types of permanent elements (atoms) occupy squares of the universe. Atoms sharing a common square form a particle, with properties determined by its component atoms. Atoms, particles, and complexes of particles move and collide according to rules like those of classical mechanics. At a higher level of organization, the string of atoms in a particle is viewed as a program, whose execution can affect the space around the particle in ways similar to the operation of enzymes. Two systems that exhibit self-replication when embedded in the universe are demonstrated. The first is very simple showing elementary self-replication activity. The second is relatively elaborate and intended to show "on paper" how a collection of particle complexes could behave in a manner resembling mitosis in a simple cell.