Previous Back to index Next

Complex patterns

1. Overweight spaceships

If we try to extend a HWSS, we find that the sparks it leaves destroy it:

What is needed is some way to suppress these sparks. It turns out that using smaller 'standard' spaceships to escort the OWSS (overweight spaceship) is the way to go:

Longer OWSS can be created using MWSS, HWSS, and (for very large ships) smaller OWSS surrounded in turn by standard spaceships. This allows arbitrarily long and wide orthogonal spaceships to be built, all travelling at c/2.

2. Puffer trains

Sometimes a pattern will repeat itself translated a few squares, but leave behind a trail of debris. These patterns are called puffer trains.

3. Glider collisions

There are many ways in which two gliders can collide. Here are some of the most useful.

First, we have simple annihilation, where both gliders die:

These are more useful than they might appear; sometimes we will want to destroy a pair of gliders.

Then there are a few reactions which create a still life – here is one that creates a block:

These can be useful when building such things as glider guns, where the structure consists of things that can be made by crashing gliders into each other and into still lives.

Finally, there is the kickback reaction, which sends one glider back along its original path and destroys the other:

4. The Gosper gun

In November 1970 Conway offered a prize to anyone who could prove or disprove his conjecture that no pattern would grow forever. Bill Gosper disproved it by discovering this pattern:

This pattern grows infinitely by creating an endless stream of gliders. This is extremely useful, since a stream of gliders can be used to represent a bitstream: the presence of a glider signifies a 1, and its absence signifies a 0.

Previous Back to index Next
Copyright © 2004
Peter Berry