Have scientists discovered a new force of nature? "Something else is going on," Neil DeGrasse Tyson says By Elizabeth Elkind New study challenges laws of physics A tiny particle, invisible to the naked eye, could expand our understanding of the natural world, according to scientists at Fermi National Accelerator Laboratory in Batavia, Illinois. The particle in question is called a muon. Similar to an electron, it releases a negative charge, but a muon is much heavier and exists at a higher energy level than its more familiar counterpart. A team of 200 physicists from seven different countries observed muons as they were shot through a magnetic field. The particle did not behave as they expected it to.