The first signs of a dark matter particle may have been spotted. If the result is confirmed, it could be one of the most monumental discoveries in the history of physics. Dark matter makes up about 85 per cent of matter in the universe, but for decades physicists have been unable to determine what it itself is made of. Hypotheses have ranged from different sorts of particles and forces to strangely behaving gravity and everything in between – but the leading idea has always been that of the weakly interacting massive particle, or WIMP. …