New Forces and Generations
According to the Standard Model, subatomic particles are arranged in three groupings known as generations, with each generation heavier than the last. Electrons, for instance, belong to the lightest generation of particles but interact similarly to the heavier muons and tau particles, which belong to the second and third generation, respectively.
But why are there only three generations? Scientists have never seen any evidence for higher generation particles but that doesn’t necessarily mean they don’t exist. Though unlikely, it was possible that the LHC could have uncovered evidence for a fourth generation, perhaps by finding a new type of never-before-seen neutrino. The best evidence against this was the discovery of the Higgs boson. If there were higher generation particles, they would have interacted with the Higgs and modified its properties from what scientists saw in July.
Similarly, there are four fundamental forces in the universe: the electromagnetic, strong, weak, and force of gravity. No other forces have ever been detected but they could still be out there. Some slight evidence suggests that dark matter may interact with itself via fundamental forces that ordinary matter lacks. Such “dark forces” could explain certain phenomena seen in small galaxies. If the LHC had seen either supersymmetric particles or dark matter, it might have also glimpsed some new and very different force of nature.
Image: The three generations of matter get heavier from left to right. The four fundamental force-carrying particles are at the farthest right. MissMJ/Wikimedia
