Thumb

A thumb is a weak spark that flicks out from an oscillator or other pattern in a manner that resembles a thumb being flicked.

Shown below is a period-4 thumb that was found by David Eppstein in June 2000, and a larger one with higher clearance found by Dongook Lee on November 13, 2019.

5bo5b$b2o3bo4b$bo5bo3b$2b3obob2ob$7b2obo$6o4bo$o4b5ob$3bo7b$2bob4o3b$ 2bobo2bo3b$3bo! #C [[ THUMBSIZE 2 THEME 6 GRID GRIDMAJOR 0 SUPPRESS THUMBLAUNCH ]] #C [[ THUMBSIZE 3 GPS 5 AUTOSTART WIDTH 560 HEIGHT 560 ]] A period 4 thumb (click above to open LifeViewer) RLE: here Plaintext: here Catagolue: here

x = 11, y = 19, rule = B3/S23 6bo$7bo$3b2o3bo$3b4obo$7bob2o$3bo3bo2bo$b2o3b2obo$bo3bo3b2o$bo4bobo$2b2ob2obo$2bo3bob2o$3b2obobo$b2o3b2o2bo$bobo3bob2o$o3b4o$b3o4b3o$4b4o2bo$3bo3bo$3b2o! #C [[ THUMBSIZE 2 THEME 6 GRID GRIDMAJOR 0 SUPPRESS THUMBLAUNCH ]] #C [[ THUMBSIZE 3 GPS 5 AUTOSTART WIDTH 560 HEIGHT 600 ZOOM 30 ]] A higher-clearance period 4 thumb (click above to open LifeViewer) Catagolue: here

On January 23, 2015, Dongook Lee found a reaction that converts drifters such as 2c/3 signals into thumb sparks, On July 6, 2022, May13 used this with 74P34 to produce a period-34 thumb sparker. Others are listed below.

• Gustone found a reaction for creating a period-3 thumb using caterer sparks on December 29, 2021, initially as a dimer based on the double caterer, but reduced it to a monomer. Later that day, Dongook Lee shared three other smaller variants. The smallest one based on keys is used in a p81 180° glider loop, the smallest known oscillator of its period.
• Dean Hickerson found a period-9 thumb sparker, thumb 1, in October 1998.
• David Eppstein found the p6 thumb on June 26, 2000.
• Martin Grant found a p5 thumb when he used it in his reduction to the period-20 glider gun on November 24, 2021. The previous form had used a half-lightweight emulator of the same period.
• Charity Engine found the p11 thumb on August 11, 2022.
• p7 thumb (produces two thumb sparks with high clearance symmetrically)

There is also an eater 3 variant that produces a thumb spark, allowing for engineered thumbs with periods 20 and above.

x = 22, y = 18, rule = B3/S23 bo$2bo$3o3$6bo$7bo$5b3o3$16b2o$11b2obo2bo2bo$10bobob2obobobo$7bo2bobo 4bo2bo$7b4ob4obo$11bo4bo$9bobo2bo$9b2o3b2o! #C [[ THUMBSIZE 2 THEME 6 GRID GRIDMAJOR 0 SUPPRESS THUMBLAUNCH ]] #C [[ THUMBSIZE 3 GPS 5 WIDTH 560 HEIGHT 600 ]]

Eater 3 variant that produces a thumb. (click above to open LifeViewer) Catagolue: here

See also

• Thumb 1 on queen bee shuttle
• Grin (oscillators exhibiting it, like Coe's p8 may substitute for thumbs in certain situations)

• Eater/block frob

• Finger

External links

• Thumb at the Life Lexicon