The Second Law of Information: _"Information Cannot Be Destroyed; Only Transformed, or Hidden"_

We propose and formalize the **Second Law of Information**: “Information cannot be destroyed; only transformed, or hidden.” This law asserts that no physical process can annihilate information outright; apparent loss invariably corresponds to transformation (redistribution or correlation) or hiding (dispersal into practically inaccessible degrees of freedom). Unlike speculative postulates, the Second Law is a descriptive generalization of extensive experimental evidence from reversible computation, the thermodynamics of information, quantum decoherence, and observational constraints on black-hole evaporation. We detail this empirical grounding, situate the law within contemporary physics and philosophy of science, and clarify its scope. The Second Law complements existing principles of information physics and imposes a strict conservation constraint analogous to, yet distinct from, energy conservation.