The Standard Model of particle physics has been remarkably successful in describing and predicting the behavior of elementary particles and their interactions. It has been rigorously tested through numerous experiments conducted at particle accelerators worldwide, including the Large Hadron Collider (LHC) at CERN.
However, despite its successes, the Standard Model is known to have limitations and is not considered a complete theory of fundamental particles and their interactions. There are several reasons why particle physicists continue to explore extensions and modifications to the Standard Model:
Unresolved questions: The Standard Model leaves several important questions unanswered, such as the nature of dark matter, the origin of neutrino masses, the hierarchy problem (the large discrepancy between the weak and gravitational forces), and the absence of a theory of quantum gravity. Exploring beyond the Standard Model is driven by the quest to address these unresolved issues.
Experimental evidence: While the Standard Model has been highly successful, there are experimental observations that hint at physics beyond its scope. For example, the discovery of neutrino oscillations demonstrated that neutrinos have non-zero masses, which is not accommodated within the original formulation of the Standard Model. This discovery implies the need for an extension to the theory.
Theoretical shortcomings: Theoretical considerations also motivate the exploration of physics beyond the Standard Model. For instance, the Standard Model does not incorporate gravity, and incorporating it in a consistent quantum framework is an ongoing challenge. Moreover, the Standard Model requires fine-tuning to explain the observed values of certain fundamental parameters, which some physicists find unsatisfying and seek to address with more elegant and natural explanations.
Regarding the viewpoint of Sabine Hossenfelder, a theoretical physicist known for her critical stance on certain aspects of fundamental physics, it is worth noting that she has expressed skepticism about the efficacy and direction of certain theoretical developments in particle physics. While her perspective has sparked important discussions within the scientific community, it is essential to recognize that there are diverse opinions among physicists, and ongoing research and experiments will ultimately determine the validity and direction of future developments.
In summary, while the Standard Model has been highly successful, there are several motivations, including unresolved questions and experimental and theoretical shortcomings, for particle physicists to explore extensions and modifications to the existing framework. The pursuit of new theories and experimental evidence is crucial to advancing our understanding of the fundamental constituents of the universe.