ABSTRACT
The vast majority of our universe is populated by two exotic entities, called dark matter (DM) and dark energy (DE). DE and DM have been postulated to explain two anomalous phenomena, the accelerating expansion of the universe and galaxies flat rotation curves. The underdetermination argument proceeds from the premise of empirical equivalence between two theories to the conclusion that the rationality of theory choice is underdetermined by evidence. Rivals to DE appeal to inhomogeneous Lemaitre-Tolman-Bondi (LTB) models, or to modified general relativity (GR). The first implies a violation of the Copernican principle, the second involves appeal to string theory, and no unique and well-motivated alternative to GR is currently available. The main rival to DM is modified Newtonian dynamics (MOND). Despite the simplicity and mathematical elegance of MOND, it has not won general consensus, because it involves a violation of Newtonian dynamics that many find unattractive.
