Modern mainstream cosmology is rooted in the Big Bang and continuous cosmic expansion, attributing extragalactic spectral redshift exclusively to galactic recession. However, this framework is plagued by unresolved contradictions: the early supermassive black hole paradox, mature high-redshift galaxy paradox, Hubble tension, and oversize large-scale structures. Mainstream theory relies on unobservable patches such as dark energy and cosmic inflation, violating simplicity and causality. Breaking the mainstream paradigm, this paper establishes a multi-center gravitational contraction model of primordial nebulae based on mass conservation, gravitational boundary laws, morphological correction, and long-term observations of nearby galaxies. With morphological correction coefficients to avoid idealized errors, we quantitatively estimate the evolutionary scale of the Milky Way nebula. Combined with the stable 2.5 million light-year distance between the Milky Way and the Andromeda Galaxy, we prove that galaxy evolution is the continuous contraction and aggregation of large-scale diffuse nebulae. We redefine the physical nature of redshift: redshift is an observational optical effect caused by galactic gravitational contraction, not evidence of cosmic expansion or galactic recession. All derivations are based on classical physics and observed astronomical data without ad hoc assumptions. This study systematically falsifies the Big Bang and cosmic expansion theories from both logical and quantitative perspectives.
Jiaqing Yan (Tue,) studied this question.