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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).

: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.

: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

: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 Now superseded by catacryst and metacatacryst.

: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 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.

Here are two examples. On the left is a p9 thumb sparker found by Dean Hickerson in October 1998. On the right is a p4 one 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

: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 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.

	.OOO
	OOO.

: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..

: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 an toroidal universe.

See also Klein bottle.

: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 object is cycled forever, forming an oscillator or a gun.

: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.

	..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..

: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 See Herschel transceiver.

:trans-loaf with tail (p1)

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

:transmitter See Herschel transmitter.

: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 reaction in which a Herschel or other active region destroys a still life, then later, having passed through the place where the still life was, recreates the still life in its original position. For an example, see transparent block reaction.

: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

: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....

: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.........

: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.) 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 22, 24, 30, 36, 44, 46, 48, 50, 54, 55, 56 and 60. (Credits for these small period guns are: p30, p46 and p60 by Bill Gosper in 1970-1971, p44 by Dave Buckingham in 1992, p50 by Dean Hickerson in 1996, p24 and p48 by Noam Elkies in 1997, p54 and p56 by Dieter Leithner in early 1998, p55 by Stephen Silver in late 1998, p22 by David Eppstein in 2000 and p36 by Jason Summers in 2004.)

The following diagram shows the p22 gun (David Eppstein, August 2000, using two copies of a p22 oscillator found earlier the same day by Jason Summers).

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

: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 Hartmut Holzwart, and is shown below in conjunction with the smallest known tubstretcher.

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

:tub with tail (p1)

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

:tugalong = tagalong

:tumbler (p14) The smallest known p14 oscillator. Found by George Collins in 1970.

	.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.

: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) Found by Dean Hickerson.

	.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 is the basis of all known p46 oscillators, and so of all known true p46 guns (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 a very large spark which is useful in a number of ways (see, for example, metamorphosis). 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........................

: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 = tub with tail

: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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