The p42 glider shuttle is a period-42 shuttle oscillator discovered by Noam Elkies in 1994. It was the first non-trivial period 42 oscillator to be discovered[note 1] and is based on a period 66 oscillator discovered by Robert Wainwright in September 1984. It works by using two copies of eater 3 and four copies of unix to shuttle two gliders back and forth. By increasing the distance between the two reflectors, oscillators of periods 42 + 24n can be created. Dean Hickerson found that the distance between the reflectors could be decreased using a custom period 6 oscillator to create a period 18 glider shuttle. In April 1992 Hickerson created another related oscillator by crossing two pairs of gliders using rephasers, which allowed the construction of oscillators of periods 246 + 24n.
A p18 glider shuttle using a custom period 6 oscillator by Dean HickersonRLE: here
A related p246 oscillator discovered by Dean HickersonRLE: here
- ↑ A period-42 oscillator, unix on 44P7.2, can be constructed from two sparkers (unix and 44P7.2) both of which were known by 1977. However, this type of oscillator is generally considered "boring", and thus not counted despite technically being non-trivial.