A new perspective on Hubble's law through a four-dimensional spatial model

Recent observations from the James Webb Space Telescope (JWST) are reshaping our view of the early universe, revealing galaxies at redshifts exceeding 14 whose apparent maturity challenges the standard ΛCDM framework. These findings raise a fundamental question: to what extent do current interpretations of cosmic distances—rooted in the FLRW metric—shape, or possibly constrain, our understanding of cosmic evolution? While the Big Bang paradigm remains robust, many of its empirical validations implicitly rely on the FLRW metric, potentially introducing a subtle circularity in model verification. This motivates a deeper examination of the conceptual foundations underlying cosmological distance, expansion, and redshift. In this work, an alternative interpretation of galactic redshift is proposed, based on a non‑FLRW metric in which the Universe is modeled as the three‑dimensional surface of a hypersphere expanding at a constant rate, with radius and the Big Bang located at its center. In this scenario, matter does not participate in the cosmological principle but instead appears as a discontinuity within an otherwise homogeneous geometric structure governed by the CMB. This framework preserves Hubble’s law while offering a finite yet unbounded Universe—one that would appear infinite and static in the absence of relativistic effects. It does not invoke dark matter or dark energy. Such a model provides a pathway for revisiting ΛCDM without discarding its empirical successes, suggesting that some of the current tensions may arise not from the data themselves but from the metric assumptions used to interpret them. While other models propose a hypersphere expanding with r = ct, an analysis of their main features reveals fundamental differences. The novelty of the model presented here — hereafter referred to as the 4-Sphere cosmology — lies in its definition of the Hubble constant: its four-dimensional geometry suggests a linear relationship between galactic recession and the arc angle (rather than the arc length). This perspective does not contest the validity of Hubble’s law, but introduces different predictions about the past and the future, which cannot be determined solely from current observations. The use of the angle instead of the arc length produces significant implications, opening the possibility of applying Special Relativity to galactic recession. The redshift, which asymptotically approaches a time horizon of roughly 5 billion years after the Big Bang, implicitly explains why, at the boundaries of the observable Universe with JWST, we should not expect to see only "baby galaxies". Based on supernova distance measurements, I suggest that the dismissal of a Doppler-type redshift interpretation for Galactic Recession might warrant further and careful reconsideration. This version also introduces a General Methodology—applicable in both SR and FLRW—that enables the validation or falsification of the model through additional supernova observations, including those obtained with JWST filters and converted into rest‑frame Johnson B and V via transmission‑curve analysis. As a broader implication, the 4‑Sphere mode of operation naturally enforces global energy conservation and establishes a direct link between entropy, reversibility, and the geometric structure of spacetime. As a pivotal outcome, we will ultimately illustrate how the 4-Sphere mode of operation implies that the spacetime structure must accommodate a universal speed limit, independent of direction or frame of reference. From this condition, the principles of Special Relativity follow directly: the constancy of the speed of light, the equivalence of inertial frames, and the Lorentz invariance of physical laws. This inductive methodology, synthesizing abstract thought and mathematical formulation, does not intrinsically furnish scientific proof; however, it undeniably strengthens the explanatory power of the model.