Any new hypothesis in Physics has to be supported by current data, and future data. We already have a very good standard model of particle physics, which has been tested at the sorts of energy levels we can reach with current technology. However it breaks down at very high energy levels (such as those found near the start of the universe), which is why new theories are needed.
Theoretical physics tries to come up with new hypotheses. These have to satisfy current data and if they manage that they are just as valid as current particle theories, as they will make identical predictions. If they can't satisfy current data they are discarded.
Theories never perfectly match the real world*. An improved theory either makes more accurate predictions, or makes them over a larger range of data (or hopefully both). They are just models of reality.
*Certainly at the moment.
Theoretical physics tries to come up with new hypotheses. These have to satisfy current data and if they manage that they are just as valid as current particle theories, as they will make identical predictions. If they can't satisfy current data they are discarded.
Theories never perfectly match the real world*. An improved theory either makes more accurate predictions, or makes them over a larger range of data (or hopefully both). They are just models of reality.
*Certainly at the moment.
