The Fermi Paradox or a Universe of Isolated Observers?

The Fermi Paradox is commonly framed as a contradiction between the apparent likelihood of extraterrestrial civilizations and the absence of observational evidence for their existence. This framing usually assumes that interstellar travel or interaction is achievable for sufficiently advanced civilizations. This paper examines a different possibility: that fundamental physical, environmental, navigational, and biological constraints may render interstellar travel impractical under known physical laws. Order-of-magnitude calculations are used to evaluate several independent constraints, including the energy required to reach relativistic velocities, the interaction between spacecraft and the interstellar medium, the precision required for interstellar navigation, and the limitations of proposed non-classical transport concepts such as tunneling, jump mechanisms, and wormholes. Biological constraints, including gravity dependence, radiation exposure, ecological requirements, and psychological factors, are also considered. The common objection that self-replicating mechanical probes escape these constraints is also examined and found to apply only to the biological subset of the barriers identified. On Earth, life appears wherever we look—within the oceans, across the land, and even deep below the surface—suggesting that life itself may not be rare. If life is widespread but constrained by the same physical limits, then the absence of observable extraterrestrial civilizations may not be paradoxical, but expected. Under this interpretation, the Fermi Paradox is reframed as a consequence of universal physical limitations rather than a lack of extraterrestrial life.