The Rule of Three Proved By Physicists

An anonymous reader writes "In 1970, Russian physicist Vitaly Efimov developed mathematical proof (PDF) that any three-particle substance, referred to as a trimer, will scale up or down in size by a factor of 22.7 and that if the particles are not all of the same type, 'the scaling factor of 22.7 decreases according to the particles' relative masses.' In 2006, physicists in Austria proved that Efimov's trimers can be created in laser-cooled environments. And now, in 2014, physicists in Austria, Germany, and the U.S. have physical proof that Efimov's trimers do indeed scale by a factor of 22.7 if they are comprised of the same particles or a lower ratio relative to their particles' masses if they are comprised of a mixture of different particles (abstract 1, abstract 2, abstract 3). 22.7 — a.k.a., the rule of three — now appears to be as significant as pi."