What is a "von neumann machine"?

Question

how does it work?

Answer 1

The original idea was proposed by John Von Neumann as a thought experiment. A Von Neumann machine as he described it would be powered by sunlight, eat sand, and produce more machines.

The idea is that metals and other elements exist in sand, and that a clever enough mechanism could extract aluminum, oxygen, iron, silicon, and enough other materials to make motors and actuators, wiring, framework, semiconductors and sensors. These components would then be assemled to make copies of the machine.

The reasoning was based on something called the Fermi paradox; where are all the alien life forms? The galaxy should be alive with aliens and their space probes, and if a single race made one Von Neumann machine and launched it to another solar system, it could reproduce ten copies, send information back home on the solar system it was in, and launch the copies to other stars.

If they traveled at 1/10 of the speed of light as an average, it would only take a little over a million years for each and every star to have a Von Neumann machine in its planetary system. So we should be able to see the signals and find these machines if aliens ever made them. And if multiple races spawned such machines, there could be whole communities of them, millions of years old, spanning the stars and traveling everywhere.

The idea also prompted Fred Saberhagen, a science fiction writer, to come up with the Berserker concept, a race of such machines that are programmed to destroy all life. If one such race of machines was made, it could account for the silence of the sky and the lack of other such machines.

In a more positive view, such machines, properly programmed, could be launched to the planets to explore and build places for us to live, so when we arrived there we would already have facilities waiting for us.

They could also build power plants, shipping systems, and free space habitats from asteroids.

Answer 2

* Von Neumann architecture, a conceptual model of a computer architecture which uses a single memory store to hold both the set of instructions for computation, and the data involved in the computation (as opposed to the Harvard architecture)
* Clanking replicators or (Universal Constructors), a type of machine or system that can replicate itself. There are several theoretical technologies which use this idea.
o Von Neumann probes are hypothetical space probes which are capable of self replication.
o Some conceptions of molecular nanotechnology have included microscopic self-replicating machines.