A von Neumann machine is either of two different machines popularized by the famous mathematician John von Neumann.

General-purpose computer

A von Neumann machine is a model created by John von Neumann for a computing machine that uses a single storage structure to hold both the set of instructions on how to perform the computation and the data required or generated by the computation. Most modern computers use this von Neumann architecture.

Universal constructor

The term von Neumann machine also refers to the idea of a self-reproducing machine, which was first examined in a rigorous manner and popularized by John von Neumann who called it a "Universal Constructor". In principle, if a machine (for example an industrial robot) could be given enough capability, raw material and instructions then that robot could make an exact physical copy of itself. The copy would need to be programmed in order to do anything. If both robots were reprogrammable, then the original robot could be instructed to copy its program to the new robot. Both robots would now have the capability of building copies of themselves.

These machines could be used to explore—or sanitize—the universe. The fact that we haven't seen any from other civilizations is a contributing element of the Fermi paradox. One of the predictions of some proponents of nanotechnology is very small Von Neumann machines which, should they become out of control, would advance over the planet as a "grey goo".

Since such a machine is capable of reproduction, some would consider it a life-form.

See also

• von Neumann architecture
• Conway's Game of Life
• Turing machine
• Random Access Machine
• von Neumann probe