A puffer (or puffer train) is an object that moves like a spaceship, except that it leaves debris behind. The first known puffers were found by Bill Gosper and travelled at c/2 orthogonally (see puffer 1 for the very first one, found in 1971). Not long afterwards, c/12 diagonal puffers were found (see switch engine). Discounting wickstretchers (which are not puffers in the conventional sense), no new velocity was obtained after this until David Bell found the first c/3 orthogonal puffer in April 1996. Since then c/5 orthogonal puffers have also been found, the first by Tim Coe in May 1997. Jason Summers built the first c/4 orthogonal puffer in January 1999, and the first 2c/5 orthogonal puffer in February 1999. In February 2004, Hartmut Holzwart found a c/4 diagonal puffer, and in September 2010, Matthias Merzenich found a c/5 diagonal puffer. In December 2013, Ivan Fomichev discovered a 2c/7 puffer, and in 2016, c/10 orthogonal puffers were found.
- Puffer train at Wikipedia