1 A Quantum Multiverse Interpretation of the Fermi Paradox: Entanglement, Observer Effects, and the Inaccessibility of Alien Civilizations VAIBHAV August 4, 2025 Abstract The Fermi paradox asks why we observe no evidence of extraterrestrial intelligence despite the apparent high probability of its existence in a vast cosmos. In this paper, we propose a novel interpretation of the Fermi paradox grounded in quantum mechanics and the multiverse. We hypothesize that the branching structure of a quantum multiverse, combined with the observer-dependent nature of wavefunction collapse (or decoherence), can render alien civilizations effectively inaccessible to us. In particular, any potential quantum correlations or entangled signals between spatially-separated observers become decohered into orthogonal branches, preventing classical communication. We develop this hypothesis by reviewing key concepts of the many- worlds interpretation, quantum entanglement, and decoherence, and by formulating simple models of observer-signal systems. We discuss how entanglement and the no- communication theorem imply that even entangled qubits exchanged by distant civilizations cannot convey usable information in isolation. The result is that alien civilizations may exist in other branches of the multiverse or be effectively hidden by quantum effects, explaining the cosmic silence. We conclude with implications for SETI, the philosophical limits of observation, and directions for further theoretical work. Keywords: Fermi paradox; many-worlds interpretation; quantum entanglement; decoherence; quantum cosmology; SETI. 1 Introduction The Fermi paradox highlights the contradiction between the high likelihood of extraterrestrial intelligent life and the lack of observed evidence for it. In principle, the vast number of stars and planets in our galaxy should have produced many civilizations capable of interstellar communication, yet the skies remain silent [7,8]. Traditional resolutions of the paradox include rare life, self-destruction of civilizations, or deliberate isolation. In this work, we propose an alternative explanation rooted in quantum theory and the notion of a multiverse. Specifically, we suggest that quantum observer effects and the branching structure of a quantum multiverse can render alien signals inherently inaccessible.