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:T = T-tetromino

:table The following induction coil.

	OOOO
	O..O

:table on table (p1)

	O..O
	OOOO
	....
	OOOO
	O..O

:tag = tagalong

:tagalong An object which is not a spaceship in its own right, but which can be attached to one or more spaceships to form a larger spaceship. For examples see Canada goose, fly, pushalong, sidecar and sparky. See also Schick engine, which consists of a tagalong attached to two LWSS (or similar).

The following c/4 spaceship (Nicolay Beluchenko, February 2004) has two wings, either of which can be considered as a tagalong. But if either wing is removed, then the remaining wing becomes an essential component of the spaceship, and so is no longer a tagalong.

	.......................O.......................
	.......................O.......................
	......................O.O......................
	...............................................
	.....................O...O.....................
	....................OO...OO....................
	..................OO.O...O.OO..................
	................OO.O.O...O.O.OO................
	............O...OOO.O.....O.OOO...O............
	............OOOOOO...........OOOOOO............
	...........O..O....O.......O....O..O...........
	...................O.......O...................
	..........OOO.....................OOO..........
	.........O.OO.....................OO.O.........
	........O..O.......................O..O........
	........O.............................O........
	.........OO.........................OO.........
	.........OO.........................OO.........
	OOO......O...........................O......OOO
	.O......OOO.........................OOO......O.
	......OO..O.........................O..OO......
	..OO.O.OOO...........................OOO.O.OO..
	.O...O.O...............................O.O...O.
	.O...OO.................................OO...O.

:tail spark A spark at the back of a spaceship. For example, the 1-bit spark at the back of a LWSS, MWSS or HWSS in their less dense phases.

:tame To perturb a dirty reaction using other patterns so as to make it clean and hopefully useful. Or to make a reaction work which would otherwise fail due to unwanted products which interfere with the reaction.

:taming See tame.

:tandem glider Two gliders traveling on parallel lanes at a fixed spacetime offset, usually as a single signal in a Herschel transceiver. See also glider pair.

:Tanner's p46 (p46) An oscillator found by Tanner Jacobi on 20 October 2017. This oscillator hassles an evolving pi-heptomino to produce an phi spark. The spark is very accessible and is able to perturb many things.

	..............O...........
	...OO.......OO.OO.........
	...OO.......OO.OO.....O.OO
	......................OO.O
	..........................
	..OO......................
	...O......................
	OOO.......................
	O.............O...........
	.............O.O.O.OO.....
	............O.OO.OO.O.....
	............O.............
	...........OO.............
The snakes can be replaced with eaters to form a slightly smaller version, as shown in the p46 MWSS gun in gliderless

The period of this new oscillator is the same as the old twin bees shuttle, and so this is able to expand the known p46 technology. For example, a p46 glider gun can be made from a Tanner's p46 and just one of the twin bees shuttles.

Acting on their own, two copies of Tanner's p46 placed at right angles to each other with their sparks interacting can produce two different p46 glider guns and a gliderless p46 MWSS gun. See p46 gun and gliderless for two of these. These are the first p46 guns found which do not use a twin bees shuttle at all.

:target A necessary component of a slow salvo recipe used by a single-arm universal constructor. A target usually consists of a single object, or sometimes a small constellation of common still lifes and/or oscillators. See intermediate target. If no hand target is available, a construction arm may be unable to construct anything, unless recipes are available to generate targets directly from the elbow.

:teardrop The following induction coil, or the formation of two beehives that it evolves into after 20 generations. (Compare butterfly, where the beehives are five cells further apart.)

	OOO.
	O..O
	O..O
	.OO.

:technician (p5) Found by Dave Buckingham, January 1973.

	.....O.....
	....O.O....
	....OO.....
	..OO.......
	.O...OOO...
	O..OO...O.O
	.OO....O.OO
	...O.O.O...
	...O...O...
	....OOO....
	......O.O..
	.......OO..

:technician finished product = technician

:technology The collective set of known reactions exploiting one subset of the Life universe. Examples of these subsets include glider synthesis, period 30 glider streams, c/3 spaceships, sparkers, Herschel conduits, and slow salvos. As new reactions and objects are found, over time any particular technology becomes more versatile and complete. Many Life experts like to concentrate on particular technologies.

:tee A head-on collision between three gliders, producing a perpendicular output glider that can be used to construct closely spaced glider salvos, or to inject a glider into an existing stream. There are several workable recipes. One of the more useful is the following, because the tandem glider can be generated by a small Herschel converter, SW1T43:

	...............O.
	..............O..
	..............OOO
	.........O.......
	.........O.O.....
	.........OO......
	.OO..............
	O.O..............
	..O..............

:teeth A 65-cell quadratic growth pattern found by Nick Gotts in March 2000. This (and a related 65-cell pattern which Gotts found at about the same time) beat the record previously held by mosquito5 for smallest population known to have superlinear growth. Now superseded by catacryst, metacatacryst, Gotts dots and wedge.

:telegraph A pattern created by Jason Summers in February 2003. It transmits and receives information using a rare type of reburnable fuse, a lightspeed wire made from a chain of beehives, at the rate of 1440 ticks per bit. The rate of travel of signals through the entire transceiver device can be increased to any speed strictly less than the speed of light by increasing the length of the beehive chain appropriately.

"Telegraph" may also refer to any device that sends and receives lightspeed signals; see also p1 telegraph, high-bandwidth telegraph.

:ternary reaction Any reaction between three objects. In particular, a reaction in which two gliders from one stream and one glider from a crossing stream of the same period annihilate each other. This can be used to combine two glider guns of the same period to produce a new glider gun with double the period.

:test tube baby (p2)

	OO....OO
	O.O..O.O
	..O..O..
	..O..O..
	...OO...

:tetraplet Any 4-cell polyplet.

:tetromino Any 4-cell polyomino. There are five such objects, shown below. The first is the block, the second is the T-tetromino and the remaining three rapidly evolve into beehives.

	OO......OOO......OOOO......OOO......OO.
	OO.......O...................O.......OO

:The Online Life-Like CA Soup Search A distributed search effort set up by Nathaniel Johnston in 2009, using a Python script running in Golly. Results included a collection of the longest-lived 20×20 soups, as well as a census of over 174 billion ash objects. It has since been superseded by Catagolue.

:The Recursive Universe A popular science book by William Poundstone (1985) dealing with the nature of the universe, illuminated by parallels with the game of Life. This book brought to a wider audience many of the results that first appeared in LifeLine. It also outlines the proof of the existence of a universal constructor in Life first given in Winning Ways.

:thumb A spark-like protrusion which flicks out in a manner resembling a thumb being flicked. Below on the left is a p9 thumb sparker found by Dean Hickerson in October 1998. On the right is a p4 example found by David Eppstein in June 2000.

	.......O..............O.....
	...OO...O.........OO...O....
	...O.....O.OO.....O.....O...
	OO.O.O......O......OOO.O.OO.
	OO.O.OO.OOOO............OO.O
	...O.O...........OOOOOO....O
	...O.O.OOO.......O....OOOOO.
	....O.O...O.........O.......
	......O..OO........O.OOOO...
	......OO...........O.O..O...
	....................O.......

:thunderbird (stabilizes at time 243)

	OOO
	...
	.O.
	.O.
	.O.

:tick = generation

:tic tac toe = octagon II

:tie A term used in naming certain still lifes (and the stator part of certain oscillators). It indicates that the object consists of two smaller objects joined point to point, as in ship tie boat.

:time bomb The following pattern by Doug Petrie, which is really just a glider-producing switch engine in disguise. See infinite growth for some better examples of a similar nature.

	.O...........OO
	O.O....O......O
	.......O....O..
	..O..O...O..O..
	..OO......O....
	...O...........

:titanic toroidal traveler The superstring with the following repeating segment. The front part becomes p16, but the eventual fate of the detached back part is unknown.

	OOOOOO
	OOO...

:TL = traffic light

:T-nosed p4 (p4) Found by Robert Wainwright in October 1989. See also filter.

	.....O.....
	.....O.....
	....OOO....
	...........
	...........
	...........
	...OOOOO...
	..O.OOO.O..
	..O.O.O.O..
	.OO.O.O.OO.
	O..OO.OO..O
	OO.......OO

:T-nosed p5 (p5) Found by Nicolay Beluchenko in April 2005.

	.....OO...............OO.OO.....O........
	..O..O.........OO.O.OOO.OO......O........
	.O.O.O.....O....O.O.OOO......OO.O........
	O..O.O.OOOOOO.....O....O.O...OO.O........
	.OO.O.O..O...OOO..O.OOOO..O.O.OO.OO......
	..O.O..OO.O..O..O.OO....OOO.O.O....OO....
	.O..O...O..O.O.OO....OOO...O.............
	.O.O.O...OOO.O...OOOO...O..O.O..OO.O..O..
	OO.O.........OO.O....O.O.O.O........O.OOO
	.O.O.O...OOO.O...OOOO...O..O.O..OO.O..O..
	.O..O...O..O.O.OO....OOO...O.............
	..O.O..OO.O..O..O.OO....OOO.O.O....OO....
	.OO.O.O..O...OOO..O.OOOO..O.O.OO.OO......
	O..O.O.OOOOOO.....O....O.O...OO.O........
	.O.O.O.....O....O.O.OOO......OO.O........
	..O..O.........OO.O.OOO.OO......O........
	.....OO...............OO.OO.....O........

:T-nosed p6 (p6) Found by Achim Flammenkamp in September 1994. There is also a much larger and fully symmetric version found by Flammenkamp in August 1994.

	......OO...OO......
	......O.O.O.O......
	.......O...O.......
	...................
	..O.O.O.....O.O.O..
	OOO.O.OO...OO.O.OOO
	..O.O.O.....O.O.O..
	...................
	.......O...O.......
	......O.O.O.O......
	......OO...OO......

:toad (p2) Found by Simon Norton, May 1970. This is the second most common oscillator, although blinkers are more than a hundred times as frequent. See also killer toads. A toad can be used as a 90-degree one-time turner.

	.OOO
	OOO.

The protruding cells at the edges can perturb some reactions by encouraging and then suppressing births on successive ticks. For example, a toad can replace the northwest eater in the Callahan G-to-H converter, allowing it to be packed one diagonal cell closer to other circuits.

:toad-flipper A toad hassler that works in the manner of the following example. Two domino sparkers, here pentadecathlons, apply their sparks to the toad in order to flip it over. When the sparks are applied again it is flipped back. Either or both domino sparkers can be moved down two spaces from the position shown and the toad-flipper will still work, but because of symmetry there are really only two different types. Compare toad-sucker.

	.O..............O.
	.O..............O.
	O.O............O.O
	.O..............O.
	.O......O.......O.
	.O......OO......O.
	.O......OO......O.
	O.O......O.....O.O
	.O..............O.
	.O..............O.

:toad-sucker A toad hassler that works in the manner of the following example. Two domino sparkers, here pentadecathlons, apply their sparks to the toad in order to shift it. When the sparks are applied again it is shifted back. Either or both domino sparkers can be moved down two spaces from the position shown and the toad-sucker will still work, but because of symmetry there are really only three different types. Compare toad-flipper.

	.O................
	.O..............O.
	O.O.............O.
	.O.............O.O
	.O......O.......O.
	.O......OO......O.
	.O......OO......O.
	O.O......O......O.
	.O.............O.O
	.O..............O.
	................O.

:toaster (p5) Found by Dean Hickerson, April 1992.

	....O......OO..
	...O.O.OO..O...
	...O.O.O.O.O...
	..OO.O...O.OO..
	O...OO.O.OO...O
	...O.......O...
	...O.......O...
	O...OO.O.OO...O
	..OO.O...O.OO..
	...O.O.O.O.O...
	...O.O.OO..O...
	....O......OO..

:toggleable gun Any gun that can be turned off or turned on by the same external signal - the simplest possible switching mechanism. An input signal causes the gun to stop producing gliders. Another input signal from the same source restores the gun to its original function. Compare switchable gun.

Here's a small example by Dean Hickerson from September 1996:

	..............OO..............O..
	..............O.O.............O.O
	..............O...............OO.
	.................................
	.................................
	.................................
	.................................
	...............O..O....b.........
	.OOOO..............O..b..........
	O...O..........O...O..bbb........
	....O...........OOOO.............
	O..O........................aaa..
	............................a....
	.............................a...
In the figure above, glider B and an LWSS are about to send a glider NW. Glider A will delete the next glider after B, turning off the output stream. But if the device were already off, B wouldn't be present and A would instead delete the leading LWSS, turning the device back on.

:toggle circuit Any signal-processing circuit that switches back and forth between two possible states or outputs. Examples include the semi-Snark and colour-preserving semi-Snark, which alternate between reflecting and absorbing input gliders. The following B-to-G converter sends alternate glider outputs in opposite directions.

	............O.....................................O........
	...........O.O...................................O.O.......
	............O.....................................O........
	...........................................................
	..........OOOOO.................................OOOOO......
	..........O....O................................O....O.....
	.............O..O..................................O..O....
	.............OO.O..O...............................OO.O..O.
	..........O.....O.O.O...........................O.....O.O.O
	.........O.O....O..O...........................O.O....O..O.
	.........O..O..OO..............................O..O..OO....
	..........OO....................................OO.........
	...........................................................
	...........................................................
	...........................................................
	.............................................OO............
	.............................................OO............
	...........................................................
	...........................................................
	...........................................................
	OO....................................OO...................
	OO....................................OO...................
	...........................................................
	...........................................................
	...........................................................
	...........................................................
	...........................................................
	...........................................................
	...........................................................
	...........................................................
	...........................................................
	...........................................................
	...........................................................
	...........................................................
	...........................................................
	...........................................................
	.........OO....................................OO..........
	.........OO....................................OO..........
	...........................................................
	OO.O.......O..........................OO.O.......O.........
	O.OO......OOO.........................O.OO......OOO........
	.........OO..O.................................OO..O.......

:TOLLCASS Acronym for The Online Life-Like CA Soup Search.

:toolkit A set of Life reactions and mechanisms that can be used to solve any problem in a specific pre-defined class of problems: glider timing adjustment, salvo creation, seed construction, etc. See also universal toolkit, technology.

:torus As applies to Life, usually means a finite Life universe which takes the form of an m × n rectangle with the bottom edge considered to be joined to the top edge and the left edge joined to the right edge, so that the universe is topologically a torus. There are also other less obvious ways of obtaining a toroidal universe.

See also Klein bottle. Every object in a torus universe obviously either dies or becomes a still life or oscillator.

:total aperiodic Any finite pattern which evolves in such a way that no cell in the Life plane is eventually periodic. The first example was found by Bill Gosper in November 1997. A few days later he found the following much smaller example consisting of three copies of a p12 backrake by Dave Buckingham.

	.........................................O.................
	........................................OOO................
	.......................................OO.O.....O..........
	.......................................OOO.....OOO.........
	........................................OO....O..OO...OOO..
	..............................................OOO....O..O..
	........................................................O..
	........................................................O..
	........................................................O..
	........................................OOO............O...
	........................................O..O...............
	........................................O..................
	........................................O..................
	.........................................O.................
	...........................................................
	...........................................................
	...........................................................
	...........................................................
	...........................................................
	...........................................................
	......................................OOO..................
	......................................O..O...........O.....
	......................................O.............OOO....
	......................................O............OO.O....
	......................................O............OOO.....
	.......................................O............OO.....
	...........................................................
	...........................................................
	...................................OOO.....................
	..................................OOOOO....................
	..................................OOO.OO.......OO........O.
	.....................................OO.......OOOO........O
	..............................................OO.OO...O...O
	................................................OO.....OOOO
	...........................................................
	...........................................................
	....................O......................................
	.....................O.....................................
	.OO.............O....O................................OOO..
	OOOO.............OOOOO..................................O..
	OO.OO...................................................O..
	..OO...................................................O...
	....................................O......................
	.....................................O.....................
	.....................OO..........O...O.....................
	......................OO..........OOOO...............OO....
	.....................OO...........................OOO.OO...
	.....................O............................OOOOO....
	...................................................OOO.....
	...........................................................
	......................OO...................................
	.............OOOO....OOOO..................................
	............O...O....OO.OO.................................
	.OOOOO..........O......OO..................................
	O....O.........O...........................................
	.....O.....................................................
	....O......................................................

:T-pentomino Conway's name for the following pentomino, which is a common parent of the T-tetromino.

	OOO
	.O.
	.O.

:track A path made out of conduits, often ending where it begins so that the active signal object is cycled forever, forming an oscillator or a gun.

This term has also been used to refer to the lane on which a glider or spaceship travels. The concept is very similar, but a reference to a "track" now usually implies a non-trivial supporting conduit.

:tractor beam A stream of spaceships that can draw an object towards the source of the stream. The example below shows a tractor beam pulling a loaf; this was used by Dean Hickerson to construct a sawtooth.

	.....................O..O......................
	.....OOOO...........O..............OOOO........
	.....O...O..........O...O..........O...O.......
	.....O........OO....OOOO...........O........OO.
	.OO...O..O...OOOO...........OO......O..O...OOOO
	O..O........OO.OO..........OO.OO..........OO.OO
	O.O..........OO.............OOOO...........OO..
	.O...........................OO................

:traffic circle (p100)

	.....................OO....OO...................
	.....................O.O..O.O...................
	.......................O..O.....................
	......................OO..OO....................
	.....................OOO..OOO...................
	.......................O..O.....................
	...............................O................
	..............................O.OO..............
	..................................O.............
	..........................O...O..O.O............
	..........................O.....O..O............
	..........................O......OO.............
	.........OO.....................................
	........O..O..........OOO...OOO.................
	.......O.O.O....................................
	......OOO.O...............O.....................
	......OOO.................O.....................
	..........................O.....................
	............OOO.................................
	OO..O................OOO........................
	O..OO.....O.....O...............................
	.OOOOO....O.....O..O.....O.................O..OO
	..........O.....O..O.....O.................OO..O
	...................O.....O.......OOO......OOOOO.
	.OOOOO......OOO.................................
	O..OO................OOO.......O.....O..........
	OO..O..........................O.....O....OOOOO.
	...............................O.....O.....OO..O
	...........................................O..OO
	.................................OOO............
	.......................................OO.......
	......................................OOO.......
	.....................................O.OO.......
	....................................O.O.........
	....................OOO.............O..O........
	.....................................OO.........
	.............OO....O..O.........................
	............O..O................................
	............O.O.O...............................
	.............O..O...............................
	.................O..............................
	..............O.O...............................
	.....................O..O.......................
	...................OOO..OOO.....................
	....................OO..OO......................
	.....................O..O.......................
	...................O.O..O.O.....................
	...................OO....OO.....................

:traffic jam Any traffic light hassler, such as traffic circle. The term is also applied to the following reaction, used in most traffic light hasslers, in which two traffic lights interact in such a way as to reappear after 25 generations with an extra 6 spaces between them. See traffic lights extruder for a way to make this reaction extensible.

	..OOO...........
	...........OOO..
	O.....O.........
	O.....O..O.....O
	O.....O..O.....O
	.........O.....O
	..OOO...........
	...........OOO..

:traffic light (p2) A common formation of four blinkers.

	..OOO..
	.......
	O.....O
	O.....O
	O.....O
	.......
	..OOO..

:traffic lights extruder A growing pattern constructed by Jason Summers in October 2006, which slowly creates an outward-growing chain of traffic lights. The growth occurs in waves which travel through the chain from one end to the other. It can be thought of as a complex fencepost for a wick that does not need a wickstretcher.

The following illustrates the reaction used, in which a newly created traffic light at the left eventually pushes the rightmost one slightly to the right.

	......................O.......................O....
	......................O.......................O....
	.........OOO..........O..........OOO..........O....
	.OO................................................
	OOO....O.....O....OOO...OOO....O.....O....OOO...OOO
	.OO....O.....O.................O.....O.............
	.......O.....O........O........O.....O........O....
	......................O.......................O....
	.........OOO..........O..........OOO..........O....

:trans-beacon on table (p2)

	....OO
	.....O
	..O...
	..OO..
	......
	OOOO..
	O..O..

:trans-boat with tail (p1)

	OO...
	O.O..
	.O.O.
	...O.
	...OO

:transceiver = Herschel transceiver.

:trans-loaf with tail (p1)

	.O....
	O.O...
	O..O..
	.OO.O.
	....O.
	....OO

:transmitter = Herschel transmitter.

:transparent In signal circuitry, a term used for a catalyst that is completely destroyed by the passing signal, then rebuilt. Often (though not always) the active reaction passes directly through the area occupied by the transparent catalyst, then rebuilds the catalyst behind itself, as in the transparent block reaction. See also transparent lane.

:transparent block reaction A certain reaction between a block and a Herschel predecessor in which the block reappears in its original place some time later, the reaction having effectively passed through it. This reaction was found by Dave Buckingham in 1988. It has been used in some Herschel conduits, and in the gunstars. Because the reaction involves a Herschel predecessor rather than an actual Herschel, the following diagram shows instead a B-heptomino (which by itself would evolve into a block and a Herschel).

	O.............
	OO..........OO
	.OO.........OO
	OO............

:transparent debris effect A mechanism where a Herschel or other active reaction completely destroys a catalyst in a particular location in a conduit. After passing through or past that location, the same reaction then recreates the catalyst in exactly its original position. This type of catalysis is surprisingly common in signal circuitry. For an example, see transparent block reaction.

The transparent object is most often a very common still life such as a block or beehive. Rarer objects are not unknown; for example, a transparent loaf was found by Stephen Silver in October 1997, in a very useful elementary conduit making up part of a Herschel receiver. However, not surprisingly, rarer objects are much less likely to reappear in exactly the correct location and orientation, so transparent reactions involving them are much more difficult to find, on average.

:transparent lane A path through a signal-producing circuit that can be used to merge signal streams. The signal is usually a standard spaceship such as a glider. It can either be produced by the circuit, or it can come from elsewhere, passing safely through on the transparent lane without interacting with the circuit.

:tremi-Snark A colour-preserving period-multiplying signal conduit found by Tanner Jacobi on 7 September 2017, producing one output glider for every three input gliders. It uses the same block-to-pre-honeyfarm bait reaction as the Snark, and so has the same 43-tick recovery time. Compare semi-Snark.

	.O............................
	..O...........................
	OOO...........................
	..............................
	..............................
	..............................
	..............................
	..............................
	..............................
	..............................
	..............................
	...........O..................
	............OO................
	...........OO.................
	..............................
	...........................O..
	.........................OOO..
	........................O.....
	........................OO....
	..............................
	..............................
	..............................
	.......................O......
	.....................O.O......
	......................OO......
	..............OO..............
	.............O.O........O.....
	.............O.........O.O....
	............OO.........O.O....
	........................O.....
	..............................
	..............................
	..............................
	.....................OO.OO....
	.................OO..OO.O...OO
	.................O......O.O..O
	..................OOOOOOO.OO..
	.........................O....
	....................OOOO.O....
	....................O..OO.....

:trice tongs (p3) Found by Robert Wainwright, February 1982. In terms of its 7×7 bounding box this ties with jam as the smallest p3 oscillator.

	..O....
	..OOO..
	OO...O.
	.O.O.O.
	.O.....
	..OO..O
	.....OO

:trigger A signal, usually a single glider, that collides with a seed constellation to produce a relatively rare still life or oscillator, or an output spaceship or other signal. The constellation is destroyed or damaged in the process; compare circuit, reflector. Here a pair of trigger gliders strike a dirty seed constellation assembled by Chris Cain in March 2015, to launch a three-engine Cordership:

	....................................................OO.
	................................................OO..OO.
	................................................OO.....
	.......................................................
	.......................................................
	.......................................................
	........................................OO.............
	........................................OO.............
	...................................................OO..
	..................................O................O.O.
	.................................O.O...........OO...O.O
	..................................OO..........O.O....O.
	...............................................O.......
	.......................................................
	..................................O.................OOO
	.................................O.O................O..
	..................................OO.................O.
	.......................................................
	.......................................................
	.......................................................
	.......................................................
	.......................................................
	.......................................................
	.......................................................
	.......................................................
	.......................................................
	.......................................................
	.......................................................
	.......................................................
	.......................................................
	.......................................................
	.......................................................
	...........................O...........................
	..........................O.O..........................
	...........................OO..........................
	.......................................................
	.......................................................
	...........................O...........................
	..........................O.O..........................
	...........................OO..........................
	.......................................................
	.......................................................
	.......................................................
	.......................................................
	.......O....O..........................................
	......O.O..O.O.........................................
	.......OO...OO.........................................
	.......................................................
	.......................................................
	.......................................................
	.......................................................
	OO.....................................................
	O.O....................................................
	.O.O...................................................
	..O....................................................
	.......................................................
	.......................................................
	.......................................................
	.............O.........................................
	............OO.........................................
	............O.O........................................

"Trigger" is also used when a spaceship reacts with another object to cause a reaction to occur whenever desired (but perhaps only at particular intervals). The object being triggered lies dormant until the reaction is required. All turners and freeze-dried constellations are triggerable.

In some cases the object is not destroyed so that the reaction can be repeated after some repeat time. See for example converter and reflector, and more specifically MWSS out of the blue and queen bee shuttle pair.

:triomino Either of the two 3-cell polyominoes. The term is rarely used in Life, since the two objects in question are simply the blinker and the pre-block.

:triple caterer (p3) Found by Dean Hickerson, October 1989. Compare caterer and double caterer.

	.....OO.........
	....O..O..OO....
	....OO.O...O....
	......O.OOO....O
	..OOO.O.O....OOO
	.O..O..O....O...
	O.O..O...O..OO..
	.O..............
	..OO.OO.OO.OO...
	...O...O...O....
	...O...O...O....

:triple pseudo The following pattern, found by Gabriel Nivasch in July 2001. It is unique among 32-bit still lifes in that it can be broken down into three stable pieces but not into two. The term may also refer to any larger stable pattern with the same property. See also quad pseudo.

	......OO
	..O.O..O
	.O.OO.O.
	.O....OO
	OO.OO...
	...OO.OO
	OO....O.
	.O.OO.O.
	O..O.O..
	OO......

:triplet Any 3-cell polyplet. There are 5 such objects, shown below. The first two are the two triominoes, and the other three vanish in two generations.

	O..................O.......O.......O..
	OO......OOO......OO.......O.O.......O.
	.....................................O

:tripole (p2) The barberpole of length 3.

	OO....
	O.O...
	......
	..O.O.
	.....O
	....OO

:tritoad (p3) Found by Dave Buckingham, October 1977.

	.........OO.......
	.........O........
	..........O..OO...
	.......OOO.O..O...
	......O....OO.O.OO
	......O.OO..O.O.OO
	...OO.O...OO..O...
	...O..OO...O.OO...
	OO.O.O..OO.O......
	OO.O.OO....O......
	...O..O.OOO.......
	...OO..O..........
	........O.........
	.......OO.........

:trivial A trivial period-N oscillator is one in which every cell oscillates at some smaller factor of N. See omniperiodic.

:true Opposite of pseudo. A gun emitting a period n stream of spaceships (or rakes) is said to be a true period n gun if its mechanism oscillates with period n. The same distinction between true and pseudo also exists for puffers. An easy way to check that a gun is true period n is to stop the output with an eater, and check that the result is a period-n oscillator.

True period n guns are known to exist for all periods greater than 61 (see My Experience with B-heptominos in Oscillators), but only a few smaller periods have been achieved, namely 20, 22, 24, 30, 36, 40, 44, 45, 46, 48, 50, and 54 through 61. See also Quetzal for the 54-61 range.

	------------------------------------
	Period  Discoverers            Date
	------------------------------------
	20      Matthias Merzenich  May 2013
	        Noam Elkies
	22      David Eppstein      Aug 2000
	        Jason Summers
	24      Noam Elkies         Jun 1997
	30      Bill Gosper         Nov 1970
	36      Jason Summers       Jul 2004
	40      Adam P. Goucher     Mar 2013
	        Matthias Merzenich
	        Jason Summers
	44      Dave Buckingham     Apr 1992
	45      Matthias Merzenich  Apr 2010
	46      Bill Gosper             1971
	48      Noam Elkies         Jun 1997
	50      Dean Hickerson      Oct 1996
	        Noam Elkies
	        Dave Buckingham
	54      Dieter Leithner     Jan 1998
	        Noam Elkies
	        Dave Buckingham
	55      Stephen Silver      Oct 1998
	56      Dieter Leithner     Jan 1998
	        Dave Buckingham
	        Noam Elkies
	57      Matthias Merzenich  Apr 2016
	58      'thunk'             Apr 2016
	        Matthias Merzenich
	        Chris Cain
	59      Adam P. Goucher     Dec 2009
	        Jason Summers
	60      Bill Gosper         Nov 1970
	61      Luka Okanishi       Apr 2016
	------------------------------------

:T-tetromino The following common predecessor of a traffic light.

	OOO
	.O.

:tub (p1)

	.O.
	O.O
	.O.

:tubber (p3) Found by Robert Wainwright before June 1972.

	....O.O......
	....OO.O.....
	.......OOO...
	....OO....O..
	OO.O..OO..O..
	.O.O....O.OO.
	O...O...O...O
	.OO.O....O.O.
	..O..OO..O.OO
	..O....OO....
	...OOO.......
	.....O.OO....
	......O.O....

:tubeater A pattern that consumes the output of a tubstretcher. The smallest known tubeater was found by Nicolay Beluchenko (September 2005), and is shown below in conjunction with the smallest known tubstretcher.

	........O....................
	.......OO....................
	.......O.O...................
	.............................
	..........OO.................
	..........OO.................
	.......................OOO...
	.O......OO...O.........O.....
	OO.....O..O.O.O.........O....
	O.O...OO.O...O.O..........OOO
	....O.........O.O............
	...O...........O.O.....OO....
	...O..O.........O.O....O.O.O.
	.................O.O...O...OO
	..................O.....O....
	...................O..OO..O..
	.....................O.OOOO..
	......................OOO...O
	..........................OO.
	...........................O.
	...........................OO
	..........................O..
	...........................OO

:tubstretcher Any wickstretcher in which the wick is two diagonal lines of cells forming, successively, a tub, a barge, a long barge, etc. The first one was found by Hartmut Holzwart in June 1993, although at the time this was considered to be a boatstretcher (as it was shown with an extra cell, making the tub into a boat). The following small example is by Nicolay Beluchenko (August 2005), using a quarter.

	.......OOO.....
	.......O.......
	........O......
	..........OO...
	...........O...
	...............
	........OO...O.
	OOO.....OO..O.O
	O......O.O...O.
	.O....OO.......
	...OOOO.O......
	....OO.........

In October 2005, David Bell constructed an adjustable high-period diagonal c/4 rake that burns tubstretcher wicks to create gliders, which are then turned and duplicated by convoys of diagonal c/4 spaceships to re-ignite the stabilized ends of the same wicks.

:tub with tail (p1) The following 8-cell still life. See eater for a use of this object.

	.O...
	O.O..
	.O.O.
	...O.
	...OO

:tugalong = tagalong

:tumbler (p14) The smallest known p14 oscillator. Found by George Collins in 1970. The oscillator generates domino sparks, but they are fragile and no use has been found for them to date. In each domino, one cell is "held" (remains alive) for two generations, the other for three. By contrast, useful domino sparks are usually alive for only one tick per oscillator period.

	.O.....O.
	O.O...O.O
	O..O.O..O
	..O...O..
	..OO.OO..

:tumbling T-tetson (p8) A T-tetromino hassled by two figure-8s. Found by Robert Wainwright.

	.OOO.................
	O..................OO
	O...O............O.OO
	O..O.O..........O....
	..O.O..O...........O.
	...O...O.......OO.O..
	.......O.......OO....
	....OOO....O.........
	.........OO..........
	...........O.........

:Turing machine See universal computer.

:turner A one-time glider reflector, or in other words a single-glider seed (the term is seldom or never used in relation to spaceships other than gliders). One-time turners may be 90-degree or 180-degree, or they may be 0-degree with the output in the same direction as the input. A reusable turner would instead be called a reflector. Shown on the top row below are the four 90-degree turner reactions that use common small ash objects: boat, eater1, long boat, and toad.

	.O..............O..............O..............O.........
	..O..............O..............O..............O........
	OOO............OOO............OOO............OOO........
	........................................................
	........................................................
	........................................................
	.....OO........OO...............O.......................
	....O.O.......O.O..............O.O...............OOO....
	.....O........O.................O.O...............OOO...
	.............OO..................OO.....................
	........................................................
	........................................................
	........................................................
	........................................................
	........................................................
	.O.............O..............................O.........
	..O.............O....OO........................O........
	OOO...........OOO....OO......................OOO........
	......................................................OO
	......................................................OO
	........................................................
	...O....................................................
	..O.O............OO..............................OO.....
	.O.O.............OO..............................OO.....
	.OO.....................................................
Of the reactions on the first row, the glider output is the same parity for all but the longboat. The three still lifes are all colour-changing, but the toad happens to be a colour-preserving turner. Many small one-time turner constellations have also been catalogued. The two-block turner directly below the toad is also colour-changing, but has the opposite parity. In the southwest corner above are two of the simplest 180-degree turners. The Blockic turner is colour-preserving. The long boat is 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 are always opposite colours.

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 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. An example is shown in demultiplexer.

:turning toads (p4 wick) Found by Dean Hickerson, October 1989.

	..............OO.....OO.....OO.....OO.....OO..............
	.......O.....O......O......O......O......O................
	......OO...O....O.O....O.O....O.O....O.O....O.O.O.OO......
	..OO.O.OOO.O..OO..O..OO..O..OO..O..OO..O..OO..O..O..O.OO..
	O..O.OO.........................................OOOOO.O..O
	OO.O..............................................OO..O.OO
	...O..................................................O...
	...OO................................................OO...

:turtle (c/3 orthogonally, p3) A spaceship found by Dean Hickerson in August 1989 that produces a domino spark at the back. Hickerson used this spark to convert an approaching HWSS into a loaf, as part of the first sawtooth. (Also see tractor beam). The shape of the back end of the turtle is distinctive. Very similar but wider back ends have been found in other c/3 ships to produce period 9 and 15 spaceships.

	.OOO.......O
	.OO..O.OO.OO
	...OOO....O.
	.O..O.O...O.
	O....O....O.
	O....O....O.
	.O..O.O...O.
	...OOO....O.
	.OO..O.OO.OO
	.OOO.......O

:twin bees shuttle (p46) Found by Bill Gosper in 1971, this was the basis of all known p46 oscillators and true p46 guns until the discovery of Tanner's p46 in 2017. See new gun for an example. There are numerous ways to stabilize the ends, two of which are shown in the diagram. On the left is David Bell's double block reaction (which results in a shorter, but wider, shuttle than usual), and on the right is the stabilization by a single block. This latter method produces the very large twin bees shuttle spark which is useful in a number of ways. See metamorphosis for an example. Adding a symmetrically placed block below this one suppresses the spark. See also p54 shuttle.

	.OO........................
	.OO........................
	...........................
	...............O...........
	OO.............OO........OO
	OO..............OO.......OO
	...........OO..OO..........
	...........................
	...........................
	...........................
	...........OO..OO..........
	OO..............OO.........
	OO.............OO..........
	...............O...........
	...........................
	.OO........................
	.OO........................

:twin bees shuttle pair Any arrangement of two twin bees shuttles such that they interact. There are many ways that the two shuttles can be placed, either head-to-head, or else at right angles. Glider guns can be constructed in at least five different ways. Here is one by Bill Gosper in which the shuttles interact head-to-head:

	.................O...............................
	OO...............OO..............................
	OO................OO.............................
	.................OO...........OO.................
	.............................O.O.................
	.............................O...................
	.............................OOO.................
	.................OO..............................
	..................OO.............................
	.................OO..............................
	.................O...........OOO.................
	.............................O.................OO
	.............................O.O...............OO
	..............................OO.................
For other examples, see new gun, edge shooter, double-barrelled and natural Heisenburp.

:twin bees shuttle spark The large and distinctive long-lived spark produced, most commonly, by the twin bees shuttle. It starts off as shown below.

	..OO.
	..OO.
	.O..O
	O.OO.
	O.OO.
After 3 generations it becomes symmetric along the horizontal axis, after 9 generations it becomes symmetric along the vertical axis also, and finally dies after 18 generations.

Since the spark is isolated and long-lived, there are many possible perturbations that it can perform. One of the most useful is demonstrated in metamorphosis where a glider is converted into a LWSS. Another useful one can turn a LWSS by 90 degrees:

	O..O.........
	....O........
	O...O.....O..
	.OOOO....OOO.
	........O...O
	........OO.OO
	........OO.OO
	.............
	........OO.OO
	........OO.OO
	........O...O
	.........OOO.
	..........O..

:twinhat (p1) See also hat and sesquihat.

	..O...O..
	.O.O.O.O.
	.O.O.O.O.
	OO.O.O.OO
	....O....

:twin peaks = twinhat

:twirling T-tetsons II (p60) Found by Robert Wainwright. This is a pre-pulsar hassled by killer toads.

	.......OO...OO..........
	......O.......O.........
	.........O.O............
	.......OO...OO..........
	........................
	........................
	........................
	.....................OOO
	....................OOO.
	.............O..........
	OOO.........OOO.........
	.OOO....................
	....................OOO.
	.....................OOO
	........................
	.OOO....................
	OOO.........OOO.........
	.............O..........
	........................
	........................
	..........OO...OO.......
	............O.O.........
	.........O.......O......
	..........OO...OO.......

:TWIT = eater5

:two-arm The type of universal constructor exemplified by the original Gemini spaceship, where two independently programmed construction arms sent gliders in pairs on 90-degree paths to collide with each other at the construction site. Construction recipes for two-arm constructors are much more efficient in general, but they require many more circuits and multiple independent data streams, which both tend to increase the complexity of self-constructing circuitry. Compare single-arm.

:two eaters (p3) Found by Bill Gosper, September 1971.

	OO.......
	.O.......
	.O.O.....
	..OO.....
	.....OO..
	.....O.O.
	.......O.
	.......OO

:two pulsar quadrants (p3) Found by Dave Buckingham, July 1973. Compare pulsar quadrant.

	....O....
	....O....
	...OO....
	..O......
	O..O..OOO
	O...O.O..
	O....O...
	.........
	..OOO....

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