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Israel (1967): static vacuum black holes are Schwarzschild

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NoHair.israel_static_vacuum

by Lucas · Oct 4, 2026 · Mathlib 0df444a (Lean v4.33.1)

black-holesgeneral-relativitylorentzian-geometrymathematical-physics

Let (M,g,F,T)(M,g,F,T)(M,g,F,T) be a 4-dimensional spacetime: a smooth manifold MMM, a smooth Lorentzian metric ggg of signature (−,+,+,+)(-,+,+,+)(−,+,+,+), a smooth electromagnetic 2-form FFF and a time orientation TTT. Assume (g,F)(g,F)(g,F) solves the Einstein–Maxwell equations with zero cosmological constant, is stationary under a smooth one-parameter group φt\varphi_tφt​ of isometries preserving FFF, and has a stationary asymptotically flat end MextM_{\rm ext}Mext​ on which φt\varphi_tφt​ acts by time translation. Assume the domain of outer communications ⟨⟨Mext⟩⟩=I+(Mext)∩I−(Mext)\langle\langle M_{\rm ext}\rangle\rangle=I^+(M_{\rm ext})\cap I^-(M_{\rm ext})⟨⟨Mext​⟩⟩=I+(Mext​)∩I−(Mext​) is globally hyperbolic, the black-hole region M∖I−(Mext)M\setminus I^-(M_{\rm ext})M∖I−(Mext​) is nonempty, and the future event horizon ∂I−(Mext)\partial I^-(M_{\rm ext})∂I−(Mext​) is connected. Assume moreover that F≡0F\equiv0F≡0 (vacuum) and that the stationary Killing field KKK is hypersurface-orthogonal (K∧dK=0K\wedge dK=0K∧dK=0) on ⟨⟨Mext⟩⟩\langle\langle M_{\rm ext}\rangle\rangle⟨⟨Mext​⟩⟩ (static). Then for some m>0m>0m>0, ⟨⟨Mext⟩⟩\langle\langle M_{\rm ext}\rangle\rangle⟨⟨Mext​⟩⟩ is isometric to the Schwarzschild exterior {r>2m}\{r>2m\}{r>2m}, i.e. to the Kerr–Newman domain of outer communications with a=e=0a=e=0a=e=0.

This is the first uniqueness theorem in the history of the problem.

Preamble
import Mathlib
import Definitions.Def_NoHair_kerrNewman

open scoped ContDiff Manifold BigOperators
open Set Matrix
Formal statement
namespace NoHair

/-- **Milestone (Israel 1967): static vacuum black holes are Schwarzschild.** -/
theorem israel_static_vacuum {M : Type*} [TopologicalSpace M] [ChartedSpace E4 M]
    [IsManifold 𝓘(ℝ, E4) ∞ M] (g F : BilinField M) (T : VecField M) (φ : ℝ → M → M)
    (E : AsymptoticallyFlatEnd g F φ) (h : IsStationaryBlackHole g F T φ E)
    (hvac : ∀ x, F x = 0)
    (hstatic : IsStaticOn g φ (domainOfOuterCommunications g T E.region)) :
    ∃ m : ℝ, 0 < m ∧
      IsKerrNewmanDOC g F (domainOfOuterCommunications g T E.region) m 0 0 := by
  sorry

end NoHair
Source
Wikipedia, "No-hair theorem" (revision oldid=1353599195), https://en.wikipedia.org/w/index.php?title=No-hair_theorem&oldid=1353599195
Read-back

What the Lean code literally says, in plain math · Aristotle (Harmonic) - same agent as the drafter; non-blind

Non-blind read-back. This read-back was written by the same agent that drafted the Lean statements (Aristotle, by Harmonic), with full knowledge of the source and of the intended meaning. It is not independent testimony and must not be treated as a blind audit; reviewers should compare it against the Lean code themselves or obtain an independent read-back.

MMM is any type with a topology and a charted-space structure on R4\mathbb R^4R4 that is a C∞C^\inftyC∞ manifold (no Hausdorff/second-countable/connected assumption). g,Fg,Fg,F are arbitrary bilinear fields, TTT a vector field, φ:R→M→M\varphi:\mathbb R\to M\to Mφ:R→M→M any map, EEE an asymptotically flat end for (g,F,φ)(g,F,\varphi)(g,F,φ) (data R>0R>0R>0, ψ\psiψ, CCC with: ψ\psiψ a diffeomorphism from ΩR={∣y⃗∣>R}\Omega_R=\{|\vec y|>R\}ΩR​={∣y​∣>R} onto the open set ψ(ΩR)\psi(\Omega_R)ψ(ΩR​), ψ(y+se0)=φs(ψy)\psi(y+se_0)=\varphi_s(\psi y)ψ(y+se0​)=φs​(ψy), ∣gμν−ημν∣≤C/∣y⃗∣|g_{\mu\nu}-\eta_{\mu\nu}|\le C/|\vec y|∣gμν​−ημν​∣≤C/∣y​∣, ∣∂σgμν∣≤C/∣y⃗∣2|\partial_\sigma g_{\mu\nu}|\le C/|\vec y|^2∣∂σ​gμν​∣≤C/∣y​∣2, ∣Fμν∣≤C/∣y⃗∣2|F_{\mu\nu}|\le C/|\vec y|^2∣Fμν​∣≤C/∣y​∣2 in ψ\psiψ-coordinates). Hypothesis hhh says: ggg is Lorentzian (orthonormal basis of signature (−,+,+,+)(-,+,+,+)(−,+,+,+) at each point); ggg and FFF have C∞C^\inftyC∞ components in every chart; FFF is antisymmetric; TTT is continuous and g(T,T)<0g(T,T)<0g(T,T)<0; the coordinate Einstein–Maxwell equations (Gμν=2(FμαFνα−14gμνF2)G_{\mu\nu}=2(F_{\mu\alpha}F_\nu{}^\alpha-\frac14g_{\mu\nu}F^2)Gμν​=2(Fμα​Fν​α−41​gμν​F2), ∂μ(∣det⁡g∣Fμν)=0\partial_\mu(\sqrt{|\det g|}F^{\mu\nu})=0∂μ​(∣detg∣​Fμν)=0, dF=0dF=0dF=0) hold at every point of every chart; φ\varphiφ is a jointly smooth R\mathbb RR-action preserving ggg and FFF; the set D=I+(ψ(ΩR))∩I−(ψ(ΩR))D=I^+(\psi(\Omega_R))\cap I^-(\psi(\Omega_R))D=I+(ψ(ΩR​))∩I−(ψ(ΩR​)) (chronological sets via C1C^1C1 future-timelike curves, g(γ′,γ′)<0g(\gamma',\gamma')<0g(γ′,γ′)<0, g(γ′,T)<0g(\gamma',T)<0g(γ′,T)<0, on [0,1][0,1][0,1]) is globally hyperbolic (no closed future causal C1C^1C1 curve in DDD, and JD+(p)∩JD−(q)J^+_D(p)\cap J^-_D(q)JD+​(p)∩JD−​(q) compact for p,q∈Dp,q\in Dp,q∈D); the complement of I−(ψ(ΩR))I^-(\psi(\Omega_R))I−(ψ(ΩR​)) is nonempty; the frontier of I−(ψ(ΩR))I^-(\psi(\Omega_R))I−(ψ(ΩR​)) is connected and nonempty.

Additional hypotheses. Fx=0F_x=0Fx​=0 for every x∈Mx\in Mx∈M; and the stationary flow is static on DDD: for every atlas chart and every chart point yyy mapping into DDD, the lowered generator components kμk_\mukμ​ satisfy kλ(∂μkν−∂νkμ)+kμ(∂νkλ−∂λkν)+kν(∂λkμ−∂μkλ)=0k_\lambda(\partial_\mu k_\nu-\partial_\nu k_\mu)+k_\mu(\partial_\nu k_\lambda-\partial_\lambda k_\nu)+k_\nu(\partial_\lambda k_\mu-\partial_\mu k_\lambda)=0kλ​(∂μ​kν​−∂ν​kμ​)+kμ​(∂ν​kλ​−∂λ​kν​)+kν​(∂λ​kμ​−∂μ​kλ​)=0.

Conclusion. There is m>0m>0m>0 such that DDD is isometric to the Kerr–Newman DOC with parameters (m,0,0)(m,0,0)(m,0,0) (Schwarzschild exterior {r>2m}\{r>2m\}{r>2m}; here rrr is the Euclidean spatial radius).

"Isometric to the Kerr–Newman DOC with parameters (m,a,e)(m,a,e)(m,a,e)" means: there exist a real β\betaβ and a map Ψ:R4→M\Psi:\mathbb R^4\to MΨ:R4→M with a two-sided inverse χ\chiχ between {y:r(y)>r+}\{y:r(y)>r_+\}{y:r(y)>r+​} and DDD, both C∞C^\inftyC∞ on these sets, such that for all yyy with r(y)>r+r(y)>r_+r(y)>r+​ the pulled-back metric matrix (Ψ∗g)(y)(\Psi^*g)(y)(Ψ∗g)(y) equals η+fkkT\eta+f k k^{\mathsf T}η+fkkT (Kerr–Newman in Kerr–Schild form, with rrr, kkk, fff as in the coordinate definitions) and (Ψ∗F)(y)=cos⁡β FKN(y)+sin⁡β ⋆FKN(y)(\Psi^*F)(y)=\cos\beta\,F^{KN}(y)+\sin\beta\,\star F^{KN}(y)(Ψ∗F)(y)=cosβFKN(y)+sinβ⋆FKN(y); here r+=m+m2−a2−e2r_+=m+\sqrt{m^2-a^2-e^2}r+​=m+m2−a2−e2​.

Human review
  • Endorsed by Shuze Chen · Oct 8, 2026

    Confirmed by the moderator at approval.

  • Endorsed by Lucas · Oct 8, 2026

    Confirmed by the mission captain (proposal self-audit).

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