Water's anomalous behavior upon freezing — ice is less dense than liquid water — has long been attributed to tetrahedral hydrogen bonding geometry. While this describes the crystal structure, it does not explain why low configurational entropy produces larger volume, nor why H₂O alone among hydrogen-bonded molecules exhibits this anomaly. Here we show that both questions are answered by Energy-Skeletal (E-S) field theory. In the E-S framework, a Skeletal-field (S-field) encodes configurational information structure and is governed by the conservation law E + S = constant. The S-field density couples to molecular configurational entropy Iconfig: highly ordered ice (Iconfig ≈ 0. 12) compresses the S-field, and volume must expand to conserve E+S. Liquid water's greater disorder (Iconfig ≈ 0. 45) relaxes this compression, enabling denser packing. This yields the volume relation V ∝ χ = 1 + αI (1 − Iconfig), with αI = 0. 18, predicting ρᵢce = 0. 949 g/cm³ (observed: 0. 917, error 3. 5%) and Tₘax = 4. 7°C (observed: 4. 0°C). Crucially, the E-S framework explains why H₂O is unique.
Lyle Semple (Mon,) studied this question.