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Title: Is there a holographic dual for non-extremal Kerr black holes?
Plain: Rapidly spinning black holes show a hidden symmetry that lets their entropy be computed with a formula from two-dimensional quantum field theories. Whether such a theory really exists for ordinary spinning black holes, like those seen by gravitational-wave detectors, is unknown.
Precise: The Kerr/CFT correspondence reproduces $S = 2\pi J/\hbar$ for extremal Kerr via the Cardy formula with central charge $c_L = 12 J/\hbar$, and hidden conformal symmetry of low-frequency wave equations (2010) extends the Cardy match to non-extremal Kerr. Determine whether a unitary 2D CFT, or another quantum system, with these central charges exists whose states are the microstates of generic Kerr with $0 < a < M$. An answer is a construction or an obstruction (for example inconsistency of the boundary conditions or of modular invariance).
Settled by: Construction of a consistent dual quantum system for generic Kerr, or a proof that the required boundary conditions admit no unitary dual.
Kind: well-posed
Answer type: yes-no
References: (empty)
Literature status: contested
Status note: Entropy matches hold, but no dual theory has been constructed as of 2026.
Posed since: 2009