This week's featured article
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| A Garden of Eden is a pattern that has no parents and thus can only occur in generation 0. The term was first used in connection with cellular automata by John W. Tukey, many years before Conway's Game of Life was conceived. It was known from the start that Gardens of Eden exist in Life because of a theorem by Edward Moore that guarantees their existence in a wide class of cellular automata. The first Garden of Eden was found by Roger Banks and the MIT group in 1971. It had a bounding box of size 33 × 9 and 226 cells. Jean Hardouin-Duparc found the second and third Gardens of Eden by computer search in 1973, which had bounding boxes of size 122 × 6 and 117 × 6. His goal was to find Gardens of Eden with minimal height. In April 2016, Steven Eker found a Garden of Eden fitting inside a 5 × 83 bounding box. It is known that no Gardens of Eden exist with height less than 4, but the question is still open for height 4.
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In the news
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- April 8: David Bell constructs and refines a puffer demonstrating that all sufficiently high c/4 diagonal rake periods are achievable. Matthias Merzenich uses this to construct a clean p3532+4N rake.
- March 31: Entity Valkyrie builds a complete 2c/3-wire-based pseudo-Heisenburp device with 742-tick repeat time.
- March 27-30: Entity Valkyrie completes a 2c/3 receiver with a repeat time of 876 ticks, which Adam P. Goucher eventually improves to 742 ticks using staged recovery mechanisms; the previous record-setting receivers needed 964 or 970 ticks to recover.
- March 20: Period1GliderGun discovers a period-26 bouncer-based reflector, the first independent reflector of this period, using components by Nico Brown and Dean Hickerson.
- March 19: Keith Amling constructs new p6 c/2 orthogonal greystretchers in which the stripes are bounded by extended tables.
- March 18: Nathaniel Johnston posts a YouTube video about the discovery of the true period-15 glider gun and period-16 glider gun, and the history leading up to those discoveries.
- March 17: James Pascua discovers the first period-16 90-degree independent reflector based on a suggestion by Matthias Merzenich, using the period-16 glider gun to hassle a honey farm predecessor and produce a banana spark. 90-degree reflectors are known for all periods except 14, 17, and 19 with periods 15, 23, and 26 having only dependent reflectors.
- March 16-17: Keith Amling completes a new c/4 diagonal unstable puffer engine (only the third known puffer engine at this speed) based on a partial result by Matthias Merzenich. Caleb R. Hilton uses sparkers to stabilise the unstable engine into explicit puffers. David Bell uses this engine to construct the first p52 c/4 diagonal rake, and "b3s23love" and Merzenich use it to substantially reduce the size of the p108 c/4 diagonal rake.
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Did you know...
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- ... that there are currently known elementary spaceships with speeds c/7 and c/10 orthogonal, but none with c/8 or c/9?
- ... that there are currently known elementary spaceships with speeds c/7, c/8, and c/12 diagonal, but none with c/9, c/10 or c/11?
- ... that Karel's p177 is the highest-period known elementary oscillator with no external support?
- ... there were no known oscillators with period 43 without the use of adjustable glider loops before the discovery of the period-43 glider gun in September 2022?
- ... that without the use of Herschel loops or adjustable glider loops, there are no known oscillators with period 89?
- ... that small stable elementary pulse dividers have been found for multipliers of ×2, ×3, ×4, ×5, ×12, ×11 and ×(6n+4), but not for ×7?
- ... that with reverse caber-tosser universal constructor technology, it is possible to build any possible glider-constructible pattern, no matter what size, using only 15 gliders?
- ... that there are at least four known ways to send information diagonally at a speed greater than the maximum spaceship speed through vacuum? (Complete mechanisms include speeds approaching c/2 via two perpendicular telegraphs, and 2c/3 via a 2c/3 wire.)
- ... that an oscillator with strict volatility 1 can be constructed for any period 945 or higher?
- ... that the original Gemini's "below-the-elbow" construction efficiency, roughly three gliders per still life, is about four times better than that of any subsequent self-constructing spaceship?
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Pattern collection
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| The LifeWiki contains one of the most comprehensive catalogues of patterns available on the internet. Within it you will find:
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