Beacon
Beacon  
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Pattern type  Oscillator  

Oscillator type  Babbling brook  
Family  Beacon  
Number of cells  6  
Bounding box  4 × 4  
Frequency class  8.8  
Period  2  
Mod  2  
Heat  2  
Volatility  0.25  
Strict volatility  0.25  
Rotor type  Diagonal onoff  
Discovered by  John Conway  
Year of discovery  1970  
 
 
 

The beacon is a common period2 oscillator composed of two diagonally touching blocks. It was found by John Conway in March 1970.^{[1]}
The beacon is the simplest onoff. Its rotor, known as diagonal onoff, can be supported by several different stators: the next smallest is seen in eater plug. It can, in some sense, be considered a billiard table.^{[2]} It is the smallest oscillator whose population is not constant.
Occurrence
 See also: List of common oscillators
The beacon is the third most common oscillator in Achim Flammenkamp's census (after the blinker and toad).^{[3]} It is also the thirteenth most common object on Adam P. Goucher's Catagolue.^{[4]} In D2 diagonal symmetry, it is the eighth most common object, being more common than the tub but less common than the ship.
Uses
Beacons are significantly more common in diagonal symmetry than asymmetrically, so they can reform when hit, such as in the p26 prepulsar shuttle. The p24 shuttle, also having diagonal symmetry, contains a beacon, although this is incidental and not a catalyst.
A beacon can perform a snaketype catalysis in one of its two phases. Specifically, in the last generation before triggering the boatbit reaction, the beacon is in the dense phase.
Reactions
Beacon is hit by two gliders and shifts by (4,4), inverts phase and emits two piheptominoes that become a halfbakery and pairs of ponds, boats and blinkers. Occurs in the exhaust of a seminatural p480 ark (Catagolue: here) (click above to open LifeViewer) 
In other rules
tlife and related rules have the isotropic transition S4q, making beacon an 8cell still life systematically named "blocktie".
See also
 Beacon variants
 Beacon maker
 Double ewe, which uses it for internal stabilisation.
References
 ↑ Dean Hickerson's oscillator stamp collection. Retrieved on March 14, 2020.
 ↑ Dave Greene (July 3, 2019). Re: Thread for basic questions (discussion thread) at the ConwayLife.com forums
 ↑ Achim Flammenkamp (September 7, 2004). "Most seen natural occurring ash objects in Game of Life". Retrieved on January 15, 2009.
 ↑ Adam P. Goucher. "Statistics". Catagolue. Retrieved on June 24, 2016.
External links
 Beacon at the Life Lexicon
 Beacon at Adam P. Goucher's Catagolue
 Beacon at Heinrich Koenig's Game of Life Object Catalogs
 Patterns
 Patterns with Catagolue frequency class 8
 Natural periodic objects
 Oscillators with 6 cells
 Periodic objects with minimum population 6
 Patterns with 6 cells
 Patterns found by John Conway
 Patterns found in 1970
 Patterns that can be constructed with 3 gliders
 Oscillators
 Beacon variants
 Babbling brooks
 Oscillators with period 2
 Oscillators with mod 2
 Oscillators with heat 2
 Oscillators with volatility 0.25
 Oscillators with strict volatility 0.25
 Oscillators with rotor Diagonal onoff
 Patterns with rectangular diagonal symmetry