P2R2 rotors In the Game of Life, the smallest Period 2 rotor consist of two active cells. A Period 2 rotor with a single bit cannot exist, and it's conjectured that no Period 2 rotor consisting of a single On bit with all the other bits Off is possible either. This means that there are only two possible arrangements for a pari of bits, as shown.

The first objects in which these rotors appear are Testtube [14P2.7] for R2-1, and the Beacon [6P2.2] for R2-2. In both cases, the rotors can be supported by a number of casings. Three are known for the first, while there are 41 for the second.

P2R2-1 casings
P2R2-1 casings

P2R2-2 casings
P2R2-2 casings

P2R2-1 Beacon inductors Because it's such a small object, the Beacon can act as an inductor in many larger objects. Shown are examples up to 15 bits in size.