Quantum mechanics is a well-established and highly successful scientific theory that has been extensively tested and confirmed by numerous experiments. It provides a mathematical framework for describing the behavior of particles at the atomic and subatomic levels and has been remarkably successful in explaining a wide range of phenomena.
The predictions of quantum mechanics have been confirmed through countless experiments, including the famous double-slit experiment and the Bell's theorem experiments. These experiments consistently show that the predictions of quantum mechanics are in excellent agreement with experimental observations.
While quantum mechanics is considered to be a proven and validated theory, there are still areas of active research and ongoing efforts to deepen our understanding. For example, the reconciliation of quantum mechanics with general relativity (the theory of gravity) is a major open question in modern physics and an area of ongoing research.
It's worth noting that science doesn't provide absolute certainty but rather a continually refined and updated understanding of the natural world. Quantum mechanics has stood up to rigorous testing and scrutiny and is widely accepted by the scientific community as a reliable and accurate description of the microscopic world.