The baryon-to-photon ratio (eta, the number density of baryons relative to photons in the early universe) appears to be a fundamental constant in Lambda-CDM that must be set by initial conditions with no physical explanation for its value. The ratio is not predicted by the theory but must be input as a boundary condition, and its particular value (approximately 6 × 10^-10) seems to emerge without clear physical justification. The tension reflects the fine-tuning problem: why should this ratio have precisely the value needed to produce the structure and element abundances we observe (Weinberg 2007; Peebles & Ratra 2003).