c/4 diagonal is a diagonal speed that is equivalent to one fourth of the speed of light.
c/4 diagonal was the first spaceship speed to be discovered when Richard Guy found the glider in 1970. The glider was the only known c/4 diagonal spaceship until Dean Hickerson's searches discovered the big glider in December 1989. Robert Wainwright then found a few small tagalongs for this spaceship, including one that could connect two or more big gliders, giving arbitrarily large c/4 diagonal spaceships. Since then many c/4 diagonal spaceships have been found, and there has been a continual search for the second smallest spaceship of this speed, the current record holder being crab, with 25 cells. Of particular note are those spaceships that produce sparks, such as Tim Coe's swan. The first higher period c/4 diagonal spaceship used two swans to pull a period 8 tagalong and was discovered by Jason Summers in November 2000. In September 2005 Hartmut Holzwart found a c/4 diagonal period 12 spaceship. There is a severe lack of higher period c/4 diagonal spaceship technology until period 4508, for which David Bell has constructed a rake with an adjustable period of 4508 + 32N, which can easily be turned into a spaceship by deleting the outgoing glider with a swan.
The first c/4 diagonal puffer was discovered by Hartmut Holzwart on February 9, 2004, which creates a tub and beehive every 28 generations. On September 30, 2005 Jason Summers constructed a period 4284 puffer that was the basis of David Bell's adjustable rake.
On October 14, 2005 David Bell constructed an adjustable period sideways rake with period 4508 + 32N based on Jason Summers' period 4284 puffer.
Hartmut Holzwart discovered the first c/4 diagonal wickstretcher, boatstretcher 1, on June 1, 1993. Holzwart also found a c/4 diagonal linestretcher on November 19, 2004. An incomplete wickstretcher was found by Paul Tooke in September 2004 for a period 6 wick, and in January 2013, Jason Summers and Matthias Merzenich found a stationary termination that completes the wickstretcher. In October 2004 Hartmut Holzwart found a c/4 diagonal eater for this wick.
Many guns have been made that shoot gliders. No gun was constructed for any other c/4 diagonal spaceship before December 2014, when refinement of the glider synthesis of the crab enabled a period-120 gun to be completed..
- Extrementhusiast (December 30, 2014). "Re: How about a crab synthesis?". Retrieved on March 20, 2016.
- Jason Summers' Status of Life page
- Jason Summers' jslife pattern collection.