Inverse Nuclear-Structure Evolution in a Stiffness Field Cosmology: A Data-Constrained Alternative to Standard Big Bang Nucleosynthesis

Standard Big Bang Nucleosynthesis (BBN) explains several light-element abundances within a hot plasma expansion history, yet faces persistent tensions such as the lithium anomaly and the unexpectedly early appearance of dust/metal enrichment in high-redshift galaxies. We present a non-metric alternative within Stiffness Field Cosmology (SFC), where the vacuum is a physical elastic medium characterized by a scalar stiffness field K(t,x). In the post-transition stiffening epoch, the global stiffness increases with cosmic time, and nuclear stability becomes an environment-dependent threshold problem governed by critical stiffness functions Kc(A). We propose an inverse structural evolution scenario: instead of bottom-up thermal synthesis, nuclear composition is shaped by top-down erosion of high-A aggregates into lighter attractors. A key requirement for observational consistency is a selective stiffness window Kc( 7Li) < K < Kc( 2H),Kc( 4He), allowing efficient destruction of 7Li while preserving deuterium and stabilizing 4He. We further introduce a two-environment processing mechanism: fragments ejected from local soft domains into globally stiff regions are rapidly driven toward ( 4He, 1H), producing a quasi-invariant helium fraction in diffuse gas and alleviating the need for a finely tuned thermal BBN epoch. We formulate minimal parameterizations, explicit inequality constraints, falsifiability criteria, and testable predictions linking early dust enrichment to outflow signatures and weak environmental helium gradients.