If dark matter were found not to exist and Einstein's theory of general relativity were proven to be incorrect, it would have significant implications for our understanding of the universe. It would require a reevaluation and revision of our current models and theories.
In such a scenario, it is unlikely that scientists would revert to using Newton's theories as the sole explanation for gravitational phenomena. Newtonian physics provides an excellent approximation for most everyday situations, but it has its limitations. It does not account for certain phenomena, such as the precession of Mercury's orbit, the bending of light around massive objects, or the behavior of gravitational fields in extreme conditions.
Instead, if general relativity were proven inadequate, scientists would need to develop new theories or modifications to existing theories to explain gravitational phenomena at all scales. Various alternative theories of gravity, such as modified Newtonian dynamics (MOND) or gravitational theories beyond general relativity, have been proposed and studied. These alternative theories aim to provide explanations for observed phenomena without the need for dark matter.
Additionally, it is important to note that even if general relativity were disproven or found to be incomplete, it would not negate all the other scientific knowledge and advancements that have been built upon its framework. The principles and understanding derived from general relativity have been crucial in various fields, such as cosmology, astrophysics, and gravitational wave astronomy. Therefore, any new theories or modifications would need to be compatible with existing scientific knowledge and observations.
In summary, if dark matter were found not to exist and general relativity were proven wrong, scientists would explore alternative theories and modifications rather than reverting solely to Newtonian physics. The scientific process would continue to advance and refine our understanding of the universe.