U-turner
| U-turner | |||||||||
| View static image | |||||||||
| Pattern type | Methuselah | ||||||||
|---|---|---|---|---|---|---|---|---|---|
| Number of cells | 10 | ||||||||
| Bounding box | 4 × 4 | ||||||||
| MCPS | 10 | ||||||||
| Lifespan | 163 generations | ||||||||
| Final population | 16 | ||||||||
| L/I | 16.3 | ||||||||
| F/I | 1.6 | ||||||||
| F/L | 0.098 | ||||||||
| L/MCPS | 16.3 | ||||||||
| Static symmetry | Unspecified | ||||||||
| Discovered by | Unknown | ||||||||
| Year of discovery | Unknown | ||||||||
| |||||||||
| |||||||||
| |||||||||
The U-turner (U in conduit names) is a somewhat common methuselah. While it had appeared in some tables of common sequences, it wasn't recognized as its own distinct object until May 4, 2021, when C28 asked what the name of a specific 10-cell object was.[1]
Commonness
According to Simon Ekström's list of common evolutionary sequences, the U-turner by itself is the 16th most common qualifying sequence, and it has a separate entry ranked 47th that evolves into a U-turner plus a dying banana spark after 30 generations, as can be seen in the eight-cell predecessor below and Raucci's p217. Combining the two puts it in 14th place. About 30% of U-turners form the latter way.
Predecessors
The U-turner has one six-cell predecessor.
| The six-cell predecessor of the U-turner (click above to open LifeViewer) |
It also has a 33-generation predecessor with 8 cells:
| The eight-cell 33-generation predecessor of the U-turner (click above to open LifeViewer) |
Evolution
The U-turner advances in one direction, with its front edge reaching a maximum displacement of 13 cells in 71 through 76 generations as part of a phi spark. It leaves a tub behind it. However, the active region turns around near generation 40. It turns around back to the first direction near generation 105. The tub is destroyed; the final ash after 163 generations is four blinkers (three quarters of a traffic light and one lone blinker) and a block.
Conduits
User C28 has made many conduits and partial conduits with a U-turner as input, but very few with a U-turner as output are known, mainly because the concept of a U-turner has not been around for long.
See also
Raucci's p217 (217 = 31×7), an oscillator that consists of four U-turners hassled by four Merzenich's p31s.
References
- ↑ C28 (May 4, 2021). Re: Thread for basic questions (discussion thread) at the ConwayLife.com forums