Reconciling the Andromeda Paradox with the Simultaneous FLRW Metric

This paper re‑examines the Andromeda Paradox—originally introduced by Roger Penrose and later popularized by modern science communicators—and demonstrates that the paradox only arises when the universe is modeled using flat Minkowski spacetime. When the scenario is placed within the Friedmann–Lemaître–Robertson–Walker (FLRW) metric, which incorporates cosmic expansion and the preferred rest frame of the cosmic microwave background (CMB), the paradox dissolves. The paper shows that FLRW spacetime provides a physically meaningful global simultaneity structure defined by cosmic time, eliminating the “tilting hyperplane” effect entirely. This leads to a cosmological argument for presentism: only the present cosmic time slice exists physically, while the past and future do not. The work also connects directly to the author’s earlier publication, Expansion as the Fundamental Invariant, by demonstrating how cosmic expansion provides the invariant temporal structure needed to resolve the paradox. Email: ellis.ammons1@gmail.com Keywords Andromeda Paradox relativity of simultaneity Minkowski spacetime FLRW metric cosmic time cosmic microwave background preferred cosmological frame comoving observers cosmic expansion presentism philosophy of time spacetime foliation general relativity large‑scale structure of the universe temporal ontology