Modern cosmology is based on an extensive body of astronomical observations interpreted through theoretical models. The expansion of the Universe, Cosmic Microwave Background Radiation (MBR), primordial abundances of light elements, and large-scale structure are commonly regarded as principal observational pillars of the Big Bang Model (BBM) and its modern ΛCDM formulation. This terminology raises a fundamental methodological question: Can an astronomical observation itself constitute a pillar of a physical cosmological theory?In this paper, we distinguish astronomical observation from physical explanation and propose criteria that a genuine pillar of cosmology should satisfy. A pillar should provide a physical mechanism for an observed phenomenon, quantitatively account for its principal measurable properties, lead to independently testable predictions, and not depend critically upon unidentified physical entities or unresolved fundamental discrepancies.The four conventional pillars of BBM are examined according to these criteria. Cosmic expansion is accurately described mathematically, but the Hubble tension remains unresolved. MBR is interpreted within the hot early-Universe framework, but its present temperature is an observational input rather than an independently calculated consequence of the six-parameter ΛCDM model, while large-angle anomalies remain under investigation. Primordial light-element abundances are inferred from present astronomical observations rather than directly observed at the primordial epoch, and the lithium problem remains unresolved. Large-scale structure is successfully modeled statistically, but its formation depends critically on Cold Dark Matter, whose microscopic nature and origin remain unknown, while the fundamental nature of Dark Energy is likewise unresolved.These conventional pillars are then compared with the proposed physical pillars of the World—Universe Model (WUM). Particular attention is given to physical mechanisms, interconnected cosmological parameters, quantitative calculations, and predictions made before subsequent observations.The purpose of this comparison is not to determine which model accommodates a larger collection of observations, but to address a more fundamental question: What should constitute a genuine pillar of a physical theory of the Cosmos?