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A turner is a one-time glider reflector, or in other words a single-glider seed. A reusable turner would instead be called a reflector. The terms "turner" and "reflector" are seldom used in relation to spaceships other than gliders. A one-time turner consists of a constellation or other pattern that can be hit by a glider to produce another glider travelling in a different direction, destroying the turner in the process. This contrasts with one-time converters, which produce an output different from the input. In a dirty turner the reaction leaves behind one or more ash objects different from the original constellation.

One-time turners are an important component for slow salvo synthesis, where they are frequently used to change the direction from which a trigger glider will hit the reaction site. They may be 90-degree or 180-degree, or they may be 0-degree with the output in the same direction as the input (in which case they may instead be referred to as one-time rephasers). Shown on the top row below are the four 90-degree turner reactions that use common small ash objects: boat, eater 1, long boat, and toad.

x = 56, y = 39, rule = B3/S23 bo14bo14bo14bo$2bo14bo14bo14bo$3o12b3o12b3o12b3o4$5b2o8b2o15bo$4bobo7b obo14bobo15b3o$5bo8bo17bobo15b3o$13b2o18b2o6$bo14bo14bo14bo$2bo14bo14b o4b2o8bo$3o12b3o12b3o4b2o6b3o$54b2o$54b2o2$3bo15b2o$2bobo13bobo12b2o 14b2o$bobo13bobo13b2o14b2o$b2o14b2o6$bo$2bo$3o4$4b2o$2bo2bo$2b2o! #C [[ THEME 6 GRID GRIDMAJOR 0 SUPPRESS THUMBLAUNCH ]] #C [[ THUMBNAIL THUMBSIZE 2 ZOOM 7 THEME 6 GPS 10 LOOP 75 ]]
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Of the reactions on the first row, the glider output is the same parity for all but the long boat. The three still lifes are all colour-changing, but the toad happens to be a colour-preserving turner. The third row shows an aircraft carrier serving as a "0-degree turner" that is also colour-changing.

Three of the simplest 180-degree turners are shown in the second row. The Blockic 180-degree turner is colour-preserving. The long boat and long ship are again colour-changing; this is somewhat counterintuitive as the output glider is on exactly the same lane as the input glider, but gliders traveling in opposite directions on the same lane always have opposite colours.

Many small one-time turner constellations have also been catalogued.[1] The 90-degree two-block turner on the right, directly below the toad, is also colour-changing but has the opposite parity.

A one-time turner reaction can be used as part of a glider injection mechanism, or as a switching mechanism for a signal. If a previous reaction has created the sacrificial bait object, then a later glider is turned onto a new path. Otherwise it passes through the area unaffected. This is one way to create simple switching systems or logic circuits such as the demultiplexer.


  1. Michael Simkin (November 27, 2014). "Splitters with common SL". Retrieved on January 28, 2018.

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