Curved Spacetime, Straight Assumptions: A Recurrent Inference Failure in Modern Astrophysics

High-energy plasma experiments, particularly quark–gluon plasma (QGP) studies in heavy-ion collider environments, are frequently described as experimental analogues of early-universe or post–Big Bang conditions. This paper argues that such interpretations arise from a recurrent inference error analogous to straight-line back-projection failure in curved spacetime: a regime mismatch in which downstream physical indicators are mistaken for origin-defining conditions. Specifically, extreme heat is often treated as a generative feature of cosmological origins, rather than as a derivative consequence of constrained energy routing within an already-established temporal and causal framework. We show that heat consistently appears as an accounting residue of denied degrees of freedom following structural constraint, not as a driver of structure formation. From this perspective, plasma represents a transitional regime characterized by partial loss of admissible degrees of freedom, not a primordial state of maximal freedom. Because laboratory plasma experiments are conducted within fixed spacetime geometry, conservation laws, and temporal ordering, they cannot reproduce or probe cosmological origin boundary conditions, regardless of energetic similarity. Clarifying the causal role of heat resolves the apparent connection between plasma experiments and cosmological origins without diminishing the experimental value of plasma physics. Instead, it restores consistency between thermodynamic interpretation and the geometric constraints that govern physical inference across domains.