Hilbert–Pólya conjecture
Construct a self-adjoint operator H whose spectrum equals the ordinates of the nontrivial zeros of the Riemann zeta function, thereby implying the Riemann Hypothesis.
References
The Hilbert-Pólya conjecture (1910s) suggests the existence of a self-adjoint operator $H$ such that the non-trivial solutions of $\zeta(1/2 + it) = 0$ are the eigenvalues of $H$.
— The Riemann Hypothesis: Past, Present and a Letter Through Time
(2602.04022 - Connes, 3 Feb 2026) in Subsubsection Hilbert spaces and spectral theory