The longevity record was established by these two collisions. They both converge on the same resulting census, but the one on the right takes 17408 generations while the one on the left takes 17641.

Correction:

Scot Ellison's smaller p5 fountain
for the p5 73-step Herschel conduit

Adjustable p5 tandem-glider conduit

The circuit's p5 limitation is somewhat mitigated by its reversibility -- there are two mirror-image ways to receive the two gliders, whereas most tandem gliders need either a left- or right-handed receiver. (Some pairs of gliders with two-cell separation, usually produced with the assistance of a boojum reflector, can be received ambidextrously by standard receivers -- but this significantly alters the timing of the circuit.)

Depending on the position of the block, either of the two gliders can be chosen to trigger the Herschel output, while the other one resets the circuit. The circuit can also be hooked up to any glider output of a Herschel track for use as a period doubling fanout device, or a two-state track switch (two circuits on two glider outputs with alternating block positions).

Nicolay Beluchenko then found that a spark from this object could be used to convert Lightweight Spaceships into Gliders. He used this reaction to create the Period 150 Pseudo-Rake shown here. The Spacehip Gun at the bottom generates a stream where each spaceship becomes a forward-moving Glider.

Mark Niemiec then came up with constructions for both these flotillas. And as he points out, there are certainly more variations with different length ships out there.

First are some Period 6 Oscillators found by Nicolay Beluchenko.

Next is a Period 30 Rotor found by Karel Suhajda that requires 4 sets of P30 Glider Guns to generate the sparks necessary to turn it into a rotor. Finding a better stabilizer would be a worthwhile small project.

David Eppstein has contributed a Period 7 Oscillator and a Period 10 Oscillator, both of which have an isolated two-bit spark appearing in the upper right corner in generation 6 and 9 respectively.

p6, p7, p8, and p22 versions of Noam Elkies'
spark-assisted glider reflection reaction,
with a previously-known p15 'kickback simulator'
included at the far right for timing comparisons.
From patterns by Jason Summers, 5-6 October 2007.

The original reflection reaction can work at higher periods; variants are shown at right with p6, p7, and p8 sparks. The reflection path is the same as a kickback reaction, but the timing is different. By comparison, a pentadecathlon-based kickback emulator (far right) is four ticks faster -- or four ticks slower, since timing can be adjusted mod 8 by changing the reflector's location.

Lx134 conduit, p8 and p4 versions -- recovery times 172 and 292
Reflector by Noam Elkies, 15 Nov 2007, improved by David Eppstein

Bill Gosper's original four-barrelled p1100 MWSS gun, circa 1984
-- perhaps only the 3rd gun pattern constructed in Conway's Life.
The bounding box is over 12,000 cells on a side.

An early LWSS gun by Bill Gosper, constructed around 1984, serves as the Rosetta Stone for the two scripting languages. This is a very large, sparse pattern of centinal reflectors, with a central column of signal splitters that produce the gliders needed to maintain eight p1100 LWSS streams.

The pattern takes up about 60K as RLE, or about 750K as a flat file; it can be reduced to about 5K of Python or Perl script (see Golly 1.3's Scripts collection). The Perl version is somewhat larger, but appears to be able to recreate the pattern slightly faster.

Four prime-number calculators:
-- 1st quadrant (upper right):
Original sieve by Dean Hickerson, 1 November 1991
-- 2nd quadrant (upper left): new sieve #1
Uses every glider relay, p60 instead of p40 LWSS rake.
-- 3rd quadrant (lower left): new sieve #2
Vertical guns replaced with an equivalent reflector.
-- 4th quadrant (lower right): new sieve #3
Contains no glider guns, only pentadecathlon reflectors.

New sieves by Jason Summers, 15 October 2005.

In the pattern at right, the LWSS streams from the two bottom quadrants are set up to annihilate each other. The top two streams -- one at 60N and one at 120N -- are reflected upward along the central axis for comparison purposes. The spaceships representing 2, the first number in each series, are exactly in alignment.]]> http://pentadecathlon.com/lifeNews/2007/12/prime_number_calculators.html http://pentadecathlon.com/lifeNews/2007/12/prime_number_calculators.html Engineered Objects Sat, 15 Dec 2007 09:35:06 -0800

Achim Flammenkamp's 12x11 Garden of Eden --
black cells ON, blue-gray cells must be OFF
Achim Flammenkamp, 23 June 2004

It is still an open question whether 11x11 or smaller Garden of Eden patterns exist.

He also found some methods that use an Integral [9.5], which however, currently don't seem to have any uses.

First is a way to build a 32 bit Period 4 Spaceship which consists of an "A" tagalong supported by a pair of Lightweight Spaceships [32P4H2V0.5], constructed by firing thirteen Gliders into a pair of Fishhook Eaters and a Boat.

Next is a construction that uses eleven Gliders to build a 32 Bit Period 20 Spaceship which consists of a B-Heptomino Engine supported by a pair of Lightweight Spaceships and a Glider [32P20H10V0.1]. The Glider tagalong suppresses a very messy exhaust from a period 20 engine, turning it into simple Spaceship.