Spaceship: Difference between revisions
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It is known that there exist spaceships travelling in all rational directions and at arbitrarily slow [[speed]]s (see [[universal constructor]]). Before 1989, however, the only known examples travelled at c/4 diagonally ([[glider]]s) or c/2 orthogonally (everything else). In 1989, [[Dean Hickerson]] started to use automated searches to look for new spaceships, and had considerable success. Other people have continued these searches using tools such as [[lifesrc]] and [[gfind]], and as a result there are now a great variety of known spaceships travelling at ten different velocities. | It is known that there exist spaceships travelling in all rational directions and at arbitrarily slow [[speed]]s (see [[universal constructor]]). Before 1989, however, the only known examples travelled at c/4 diagonally ([[glider]]s) or c/2 orthogonally (everything else). In 1989, [[Dean Hickerson]] started to use automated searches to look for new spaceships, and had considerable success. Other people have continued these searches using tools such as [[lifesrc]] and [[gfind]], and as a result there are now a great variety of known spaceships travelling at ten different velocities. | ||
<table border="0" cellpadding="0" cellspacing="0" width="100%"><tr><td align="center" width="50%"> | |||
{| class="wikitable" | |||
|- | |||
! Speed | |||
! First discovered | |||
! Discoverer | |||
! Year of discovery | |||
|- | |||
! c/2 | |||
| [[Lightweight Spaceship]] | |||
| [[:Category:Patterns found by John Conway|John Conway]] | |||
| [[:Category:Patterns found in 1970|1970]] | |||
|- | |||
! c/3 | |||
| ? | |||
| [[:Category:Patterns found by Dean Hickerson|Dean Hickerson]] | |||
| [[:Category:Patterns found in 1989|1989]] | |||
|- | |||
! c/4 | |||
| ? | |||
| [[:Category:Patterns found by Dean Hickerson|Dean Hickerson]] | |||
| [[:Category:Patterns found in 1989|1989]] | |||
|- | |||
! c/5 | |||
| [[Snail]] | |||
| [[:Category:Patterns found by Tim Coe|Tim Coe]] | |||
| [[:Category:Patterns found in 1996|1996]] | |||
|- | |||
! 2c/5 | |||
| ? | |||
| [[:Category:Patterns found by Dean Hickerson|Dean Hickerson]] | |||
| [[:Category:Patterns found in 1991|1991]] | |||
|- | |||
! c/6 | |||
| [[Dragon]] | |||
| [[:Category:Patterns found by Paul Tooke|Paul Tooke]] | |||
| [[:Category:Patterns found in 2000|2000]] | |||
|- | |||
! 2c/7 | |||
| [[Weekender]] | |||
| [[:Category:Patterns found by David Eppstein|David Eppstein]] | |||
| [[:Category:Patterns found in 2000|2000]] | |||
|- | |||
! 17c/45 | |||
| [[Caterpillar]] | |||
| [[:Category:Patterns found by Gabriel Nivasch|Gabriel Nivasch]] | |||
| [[:Category:Patterns found in 2004|2004]] | |||
|- | |||
! c/4 Diagonal | |||
| [[Glider]] | |||
| Richard Guy | |||
| [[:Category:Patterns found in 1970|1970]] | |||
|- | |||
! c/5 Diagonal | |||
| ? | |||
| [[:Category:Patterns found by Jason Summers|Jason Summers]] | |||
| [[:Category:Patterns found in 1996|1996]] | |||
|- | |||
! c/6 Diagonal | |||
| [[Seal]] | |||
| [[:Category:Patterns found by Paul Tooke|Paul Tooke]] | |||
| [[:Category:Patterns found in 2000|2000]] | |||
|- | |||
! c/12 Diagonal | |||
| [[Cordership]] | |||
| [[:Category:Patterns found by Dean Hickerson|Dean Hickerson]] | |||
| [[:Category:Patterns found in 1991|1991]] | |||
|- | |||
|}</td><td align="center" width="50%"> | |||
{| class="wikitable" | |||
|- | |||
! Speed | |||
! Smallest known | |||
! Minimum # of [[cell]]s | |||
|- | |||
! c/2 | |||
| [[Lightweight Spaceship]] | |||
| [[:Category:Patterns with 9 cells|9]] | |||
|- | |||
! c/5 | |||
| [[Spider]] | |||
| [[:Category:Patterns with 58 cells|58]] | |||
|- | |||
! c/6 | |||
| [[Dragon]] | |||
| [[:Category:Patterns with 102 cells|102]] | |||
|- | |||
! 2c/7 | |||
| [[Weekender]] | |||
| [[:Category:Patterns with 36 cells|36]] | |||
|- | |||
! c/4 Diagonal | |||
| [[Glider]] | |||
| [[:Category:Patterns with 5 cells|5]] | |||
|- | |||
! c/6 Diagonal | |||
| [[Seal]] | |||
| [[:Category:Patterns with 170 cells|170]] | |||
|- | |||
! c/12 Diagonal | |||
| [[4-engine Cordership]] | |||
| [[:Category:Patterns with 134 cells|134]] | |||
|} | |||
</td></tr></table> | |||
==See also== | ==See also== | ||
Revision as of 15:05, 11 April 2009
A spaceship (or, much less commonly, a fish) is a finite pattern that reappears (without additions or losses) after a number of generations (known as its period) and is displaced by a non-zero amount. By far the most naturally-occurring spaceships are the glider, lightweight spaceship, middleweight spaceship and heavyweight spaceship.
It is known that there exist spaceships travelling in all rational directions and at arbitrarily slow speeds (see universal constructor). Before 1989, however, the only known examples travelled at c/4 diagonally (gliders) or c/2 orthogonally (everything else). In 1989, Dean Hickerson started to use automated searches to look for new spaceships, and had considerable success. Other people have continued these searches using tools such as lifesrc and gfind, and as a result there are now a great variety of known spaceships travelling at ten different velocities.
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See also
External links
- Spaceship at the Life Lexicon