Key physics: Hydrophobic solutes don't "repel" water — water is repelled by losing H-bond partners. The solvation shell water is more ordered (lower entropy).
Thermodynamics: ΔG = ΔH − TΔS. At room T, TΔS dominates: clustering reduces total ordered water, increasing entropy → spontaneous aggregation.
Scale: γ ≈ 25 cal/mol/Ų for small solutes. Oils have ~20 Ų per CH₂ → ΔG ≈ 0.7 kcal/mol per group.
Blue dots = ordered "iceberg" water; white = bulk water