Spaceship: Difference between revisions
→Spaceship Speed: spaceships travelling at arbitrary speed/direction are actually known to exist; they just haven't been built yet. Reworded section a bit, inserted reference via template |
m →History: minor grammar/typo fixes. put pattern names in lower case to be consistent with the rest of the wiki |
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==History== | ==History== | ||
the four smallest spaceships in life, the [[glider]], [[lightweight spaceship]], [[middleweight spaceship]] and [[heavyweight spaceship]], were all found by hand in 1970. For almost twenty years spaceship development was limited to adding [[Tagalong|tagalongs]] the known c/2 spaceships. Significant advances in spaceship technology came when, in 1989, [[Dean Hickerson]] began using automated searches to find spaceships. These | the four smallest spaceships in life, the [[glider]], [[lightweight spaceship]], [[middleweight spaceship]] and [[heavyweight spaceship]], were all found by hand in 1970. For almost twenty years spaceship development was limited to adding [[Tagalong|tagalongs]] the known c/2 spaceships. Significant advances in spaceship technology came when, in 1989, [[Dean Hickerson]] began using automated searches to find spaceships. These searches found orthogonal spaceships with speeds of c/3 c/4 and 2c/5, and also the first spaceship to move at the speed of c/4 diagonally other than the glider, dubbed the [[big glider]]. Hickerson also found a way to combine [[switch engine]]s to create the first diagonal c/12 spaceship. The next new spaceship speed to be discovered was the orthogonal c/5 [[snail]], found by [[Tim Coe]] in 1996, with a search program he had designed that could split tasks between multiple CPUs<ref>Tim Coe, [http://www.radicaleye.com/lifepage/patterns/p5ss.html "c/5 Orthogonal spaceship"] Paul's Page of Conway's Life Miscellany</ref>. | ||
<table border="0" cellpadding="0" cellspacing="0" width="100%"><tr><td align="center" width="50%"> | <table border="0" cellpadding="0" cellspacing="0" width="100%"><tr><td align="center" width="50%"> | ||
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|- | |- | ||
! c/2 | ! c/2 | ||
| [[ | | [[lightweight spaceship]] | ||
| [[:Category:Patterns found by John Conway|John Conway]] | | [[:Category:Patterns found by John Conway|John Conway]] | ||
| [[:Category:Patterns found in 1970|1970]] | | [[:Category:Patterns found in 1970|1970]] | ||
| Line 37: | Line 37: | ||
|- | |- | ||
! c/5 | ! c/5 | ||
| [[ | | [[snail]] | ||
| [[:Category:Patterns found by Tim Coe|Tim Coe]] | | [[:Category:Patterns found by Tim Coe|Tim Coe]] | ||
| [[:Category:Patterns found in 1996|1996]] | | [[:Category:Patterns found in 1996|1996]] | ||
| Line 47: | Line 47: | ||
|- | |- | ||
! c/6 | ! c/6 | ||
| [[ | | [[dragon]] | ||
| [[:Category:Patterns found by Paul Tooke|Paul Tooke]] | | [[:Category:Patterns found by Paul Tooke|Paul Tooke]] | ||
| [[:Category:Patterns found in 2000|2000]] | | [[:Category:Patterns found in 2000|2000]] | ||
|- | |- | ||
! 2c/7 | ! 2c/7 | ||
| [[ | | [[weekender]] | ||
| [[:Category:Patterns found by David Eppstein|David Eppstein]] | | [[:Category:Patterns found by David Eppstein|David Eppstein]] | ||
| | | 2000 | ||
|- | |- | ||
! 17c/45 | ! 17c/45 | ||
| [[ | | [[caterpillar]] | ||
| [[:Category:Patterns found by Gabriel Nivasch|Gabriel Nivasch]] | | [[:Category:Patterns found by Gabriel Nivasch|Gabriel Nivasch]] | ||
| [[:Category:Patterns found in 2004|2004]] | | [[:Category:Patterns found in 2004|2004]] | ||
|- | |- | ||
! c/4 Diagonal | ! c/4 Diagonal | ||
| [[ | | [[glider]] | ||
| Richard Guy | | Richard Guy | ||
| [[:Category:Patterns found in 1970|1970]] | | [[:Category:Patterns found in 1970|1970]] | ||
| Line 72: | Line 72: | ||
|- | |- | ||
! c/6 Diagonal | ! c/6 Diagonal | ||
| [[ | | [[seal]] | ||
| [[:Category:Patterns found by Nicolay Beluchenko|Nicolay Beluchenko]] | | [[:Category:Patterns found by Nicolay Beluchenko|Nicolay Beluchenko]] | ||
| [[:Category:Patterns found in 2005|2005]] | | [[:Category:Patterns found in 2005|2005]] | ||
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|- | |- | ||
! c/2 | ! c/2 | ||
| | | lightweight spaceship | ||
| [[:Category:Patterns with 9 cells|9]] | | [[:Category:Patterns with 9 cells|9]] | ||
|- | |- | ||
! c/5 | ! c/5 | ||
| [[ | | [[spider]] | ||
| [[:Category:Patterns with 58 cells|58]] | | [[:Category:Patterns with 58 cells|58]] | ||
|- | |- | ||
! c/6 | ! c/6 | ||
| | | dragon | ||
| [[:Category:Patterns with 102 cells|102]] | | [[:Category:Patterns with 102 cells|102]] | ||
|- | |- | ||
! 2c/7 | ! 2c/7 | ||
| | | weekender | ||
| [[:Category:Patterns with 36 cells|36]] | | [[:Category:Patterns with 36 cells|36]] | ||
|- | |- | ||
! 17c/45 | ! 17c/45 | ||
| | | caterpillar | ||
| [[:Category:Patterns with 1000 or more cells|11880063]] | | [[:Category:Patterns with 1000 or more cells|11880063]] | ||
|- | |- | ||
! c/4 Diagonal | ! c/4 Diagonal | ||
| | | glider | ||
| [[:Category:Patterns with 5 cells|5]] | | [[:Category:Patterns with 5 cells|5]] | ||
|- | |- | ||
! c/6 Diagonal | ! c/6 Diagonal | ||
| | | seal | ||
| [[:Category:Patterns with 170 cells|170]] | | [[:Category:Patterns with 170 cells|170]] | ||
|- | |- | ||
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|} | |} | ||
</td></tr></table> | </td></tr></table> | ||
==See also== | ==See also== | ||
Revision as of 12:23, 18 April 2009
A spaceship (much less commonly referred to as a glider[1] or a fish[2]) is a finite pattern that returns to its initial state after a number of generations (known as its period) but in a different location.
Spaceship Speed
- Main article: Speed
The speed of a spaceship is the number of cells that the pattern moves during its period. This is expressed in terms of c (the metaphorical "speed of light") which is one cell per generation; thus, a spaceship with a period of five that moves two cells to the left during its period travels at a speed of 2c/5. All known spaceships in life travel either orthogonally (displacement in only the x or y direction) or diagonally (equal displacement in both the x and y directions) at one of the twelve known speeds; however spaceships traveling in other directions and at different speeds have been constructed in other two dimensional cellular automata[3], and it is known that Life has spaceships that travel in all rational directions at arbitrarily slow speeds (see universal constructor).
History
the four smallest spaceships in life, the glider, lightweight spaceship, middleweight spaceship and heavyweight spaceship, were all found by hand in 1970. For almost twenty years spaceship development was limited to adding tagalongs the known c/2 spaceships. Significant advances in spaceship technology came when, in 1989, Dean Hickerson began using automated searches to find spaceships. These searches found orthogonal spaceships with speeds of c/3 c/4 and 2c/5, and also the first spaceship to move at the speed of c/4 diagonally other than the glider, dubbed the big glider. Hickerson also found a way to combine switch engines to create the first diagonal c/12 spaceship. The next new spaceship speed to be discovered was the orthogonal c/5 snail, found by Tim Coe in 1996, with a search program he had designed that could split tasks between multiple CPUs[4].
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See also
Notes
- ↑ Glider the Life Lexicon
- ↑ Fish the Life Lexicon
- ↑ "Gliders in Life-Like Cellular Automata". David Eppstein. Retrieved on April 18, 2009.
- ↑ Tim Coe, "c/5 Orthogonal spaceship" Paul's Page of Conway's Life Miscellany
External links
- Spaceship at the Life Lexicon
- Gliders in Life-Like Cellular Automata, a database maintained by David Eppstein.