Alexander Peter Marquese's Home Page

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Self-replicating blocks

Self-replication is something that all living things do (some creatures cannot reproduce, but every creature comes from reproduction). It is one of the perquisites for evolution and a way for living things to maintain their entropy levels constant, instead of increasing like in every other physical system.

One of the first examples of mechanical self replication is from Lionel Sharples Penrose (here is his wikipedia entry). He is the father of the famous physicist Sir Roger Penrose. The picture of this device of shown below and is found in Ch 3.3 of the free on-line version of the book: Kinematic Self-Replicating Machines by Robert A. Freitas Jr. and Ralph C. Merkle. In this book you can find close to all of the mechanical self-replicating machines ever invented.

At first I wanted to recreate Penrose’s design for the blocks but I didn’t have enough money or woodworking skills. I also had a few permanent magnets lying around so I made a new design of self-replicating blocks with them (some steps in one self replication are shown below):

The first assembled piece shown is the referred to the seed since it needs to be built before self-replication can take place. The same seed is needed in Penrose’s construction. There is a mistake in the lever with the small orange magnet in the middle piece. The lever stays flush with the middle piece after the assembled pieces assemble another group of pieces. This can cause two middle pieces to attach before the two last pieces attach; then either the last piece comes in and the replication process continues or the first piece comes before it and you end up with an incomplete replication; just the first and the second piece joined. I fixed that afterwards with a magnet on the lever and another magnet glued on the side of the big orange magnet in the middle piece. They repel afterwards and the lever is not flush with the piece. I’m assuming this whole issue will take place if the pieces could move at random in a surface (like an air hockey table). All the spacings of the magnets were designed so that all the pieces with attach in the right place and in the right order.

The whole process is shown in the video below:

The objective of this design was to make a cheap and easy to make mechanical replicator that is able to replicate itself if placed in an air table and if all the components undergo small random motions.