What is the universe made of? Most people would say atoms, but that’s not the whole story. We know that atoms are made up of protons, neutrons and electrons, because when radioactive atoms decay, they emit those particles. Actually, the situation is still more complicated. There is a different type of decay, beta decay, which is how physicists discovered the electron neutrino. After that, many different types of particles were discovered by particle accelerators, such as the LHC. Another way of discovering new particles has been to detect ones that stars emit. In the end, there were too many particles to keep track of. For that reason, physicists created different models, the most successful one being the Standard Model. The Standard Model is a theory of particle physics used for making experimental predictions. It explains that protons and neutrons are made out of quarks, but electrons cannot be split.
The Standard Model was put together in the 1970s. Since then, it has been the most reliable theory in particle physics. The Standard Model is used to make accurate predictions about what happens when you collide particles. Generally, a prediction is an educated guess for the result of an experiment. For instance, the Standard Model predicted that the Higgs boson exists. The prediction was checked in 2012 at the Large Hadron Collider, so physicists know that it was correct.
While the Standard Model is very successful, it also has serious problems. More specifically, the model does not explain gravity. Adding a hypothesized graviton would not entirely explain gravity, because every prediction of the Standard Model would blow up to infinity. Another example is the matter-antimatter symmetry. The Standard Model predicts that the Big Bang should have produced equal amounts of matter and antimatter, yet when we look around we see mostly matter. Most seriously, the model predicted that neutrinos have no rest mass, although scientific experiments have concluded otherwise.
If we didn’t use the Standard Model, we would have to use another of the many models. Most, if not all other theories have more problems than the Standard Model. For example, a preon model is a model that includes preons, the particles that quarks are made out of. Unfortunately for preon models, they predict that preons are about 50,000 times as large as the rest mass of an up quark, since quarks are made of preons, a preon can not be bigger than a quark, so this is a problem. Another proposal, a Grand Unified Theory (GUT), only predicts particles that have at least a GUT scale of 1016 GeV, much more than the 125 GeV of the Higgs Boson. One can not test if it is true or not, because to do that, there would have to be a particle accelerator with a bigger diameter than Earth!
I believe that in order to fix the errors in the Standard Model, physicists should build bigger particle accelerators. With bigger accelerators, some of the difficulties would be resolved, because some of them require the discovery of new particles. With this, the Standard Model would improve.