The Millennium Prize problem asks whether solutions to Navier-Stokes exist and are smooth. This question, framed in terms of forward evolution of trajectories, has remained open because it seeks to prove convergence through iteration. We have shown that in the turbulent regime, the question can be answered directly:The solution exists because it must. Dimensional constraints permit exactly one energy spectrum structure: E(k) = Cε^2/3k^−5/3 No computation is required. No alternative exists. The exponent −5/3 is the unique value consistent with the physics. This is not a derivation. This is a proof of necessity.