Pre-pulsar
The pre-pulsar is a common predecessor of the pulsar. It duplicates itself after 15 generations, although it fails to be a true replicator because of the way that the two copies then interact.
Pre-pulsar | |||||||
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Pattern type | Miscellaneous | ||||||
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Number of cells | 16 | ||||||
Bounding box | 9×3 | ||||||
Discovered by | John Conway | ||||||
Year of discovery | 1970 | ||||||
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A pair of tubs can be placed to eat half of the pre-pulsar as it replicates; this gives the period-30 oscillator Eureka, where the pre-pulsar's replication becomes a movement back and forth. The replication of the pre-pulsar can also be made to occur in just 14 generations as half of it is eaten; this allows the construction of period 28 and period 29 oscillators. The pre-pulsar was a vital component in the construction of the first oscillators of periods 26, 28, 29, 47, and 55.
A skewed pre-pulsar is like a pre-pulsar, however, the pre-traffic lights it is composed of are vertically skewed by two cells. Despite this it manages to replicate itself and becomes two skewed halves of a pulsar. This form, however, is unstable and so is not truly a pulsar predecessor, but it can be hassled similarly to a normal pre-pulsar by oscillators and spaceships.
Other pre-pulsar like formations, such as 3 in a row instead of 2, also duplicate themselves like the others, but are not stable.