The standard model cannot explain why neutrinos have mass, or why electron- positron asymmetry existed in the early universe. Do these failings make it an incomplete theory? Should all of its predictions be ignored until the theory can resolve these remaining issues?

The Standard Model, an essential theory in particle physics, initially posited that neutrinos are massless. However, numerous experiments have revealed that neutrinos do in fact have mass. These discoveries led to groundbreaking insights into the nature of neutrinos and their impact on the universe.
Neutrinos come in three types, or flavors: electron neutrinos, muon neutrinos, and tau neutrinos. One of the key experiments, the observation of neutrino oscillations, showed that neutrinos change from one type to another as they travel. This phenomenon is only possible if neutrinos have mass.
The significant question is why the Standard Model cannot account for neutrino mass. This limitation hints at the presence of new physics beyond the Standard Model. Several theories, such as the seesaw mechanism, have been proposed to explain neutrino mass, but none have been confirmed experimentally. Despite this gap, the Standard Model remains crucial for explaining many other observed phenomena in particle physics.

Another significant limitation of the Standard Model is its inability to explain the electron-positron asymmetry that existed in the early universe. According to our understanding, the Big Bang should have produced equal amounts of matter and antimatter. This symmetry implies that electrons and positrons should also have been created in equal numbers.
However, observations show a clear dominance of electrons over positrons. This matter-antimatter asymmetry is essential for the existence of the universe as we know it. If equal numbers of electrons and positrons had been created, they would annihilate each other upon contact, leaving behind only radiation and no matter.
The current Standard Model does not provide a mechanism to explain this asymmetry. Theories such as baryogenesis and leptogenesis suggest processes that might have created an imbalance between matter and antimatter, but these ideas are not fully incorporated into the Standard Model. This deficit points to the need for additional theories or extensions to our current understanding.

Particle physics is the field of science that studies the fundamental particles and forces that constitute the universe. The Standard Model of particle physics is a highly successful theory that describes three of the four known fundamental forces: electromagnetic, weak, and strong interactions. It also classifies all known elementary particles.
Despite its success in explaining a wide range of phenomena, the Standard Model has notable limitations. It does not incorporate gravity, the fourth fundamental force described by General Relativity. It also fails to explain certain observed phenomena, such as neutrino mass and matter-antimatter asymmetry, as discussed earlier.
Scientists continue to conduct experiments to test the predictions of the Standard Model and search for new particles and interactions that might reveal physics beyond the Standard Model. Large experiments, like those conducted at the Large Hadron Collider (LHC), have already led to significant discoveries, such as the Higgs boson.
Overall, while the Standard Model is an indispensable tool in particle physics, it is clear that our understanding of the universe is still incomplete. Future research aims to build upon this foundational theory and unravel the remaining mysteries of the cosmos.