The Three Different Symmetries of Particle Physics

By the late 1960s, all of this had kind of come together. Physicists like Sheldon Glasshouse, Steve Weinberg and Abda Salom had kind of worked at the mathematics that correspond to the three different forces we're talking about. Today, the heaviest known particle is the top quark. This was discovered in the 1990s at Fermilab. To put in context, it's about 340,000 times heavier than an electron.