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2005 February 21

Methuselahs
New Methuselah Records

Tomas Rokicki has announced some of the results of a survey for methuselahs. The table below shows the record holding patterns for given bit sizes. More information can be found at his webpage. Other information about methuselahs, can be found at Dean Hickerson's website. Andrzej Okrasinski also announced his finding of the current record holding pattern.

Size Name Gens Final Pop. Final Pattern, Census & Discoverer
r pentomino
r Pentomino
1103 128 r pentomino
8(4.1), 1(5.1), 1(6.2), 4(6.4), 1(7.4), 4(3P2.1), 6(5P4H1V1.1)
5 r pentomino 1105
6 r pentomino 1108
7 Acorn
Acorn

[Charles Corderman]
5206 633 Acorn
34(4.1), 8(5.1), 3(6.2), 30(6.4), 2(6.5), 5(7.4), 2(8.7), 1(8.8), 41(3P2.1), 13(5P4H1V1.1)
8 New Methuselah
[Tomas Rokicki]
7467 952 New Methuselah
51(4.1), 2(4.2), 11(5.1), 4(6.2), 35(6.4), 16(7.4), 2(8.7), 1(14.475), 61(3P2.1), 1(6P2.1), 24(5P4H1V1.1)
Bunnies
Rabbits

[Andrew Trevorrow]
17331 1749 Bunnies
109(4.1), 4(4.2), 18(5.1), 7(6.2), 65(6.4), 18(7.4), 3(8.7), 136(3P2.1), 2(6P2.1), 40(5P4H1V1.1)
9 Bunnies9
[Paul Callahan]
17410
10 Bunnies0
[Tomas Rokicki]
17423
11 Bunnies11
[Tomas Rokicki]
17465
12-18 New Methuselah
[Tomas Rokicki]
23334 2898 New Methuselah
207(4.1), 7(4.2), 23(5.1), 12(6.2), 115(6.4), 2(7.2), 32(7.4), 4(8.7), 171(3P2.1), 1(6P2.1), 2(6P2.2), 70(5P4H1V1.1), 1(9P4H2V0.1)
19 New Methuselah
[Andrzej Okrasinski]
28786 3091 New Methuselah
196(4.1), 6(4.2), 31(5.1), 9(6.2), 143(6.4), 3(6.5), 34(7.4), 6(8.7), 2(12.41), 1(14.475), 213(3P2.1), 47(5P4H1V1.1)

Note: Not all of the paths of escaped gliders are shown.

2005 February 07

Engineered Objects
Stable 2c/3 signal receiver

On 23 January 2005, Noam Elkies found a collision of 8 gliders with an LWSS that could repeatably create an input signal travelling at two thirds of the speed of light (2c/3) in the "transmitter" end of Dean Hickerson's stable diagonal 2c/3 "signal track" from 18 March 1997.

Stable 2c/3 signal receiver; recovery time = 2175 ticks The new signal-inserting collision is shown on the left edge of the pattern below; the rest of the pattern is a stable 2c/3 signal receiver constructed by dgreene on February 6.

One remaining open problem is the construction of a similar stable pattern to produce the "transmitter" collision from a single input signal.