Classical event horizon and Schwarzschild radius
A classical black-hole event horizon is a causal boundary: signals from its interior cannot reach distant future observers in the exterior.
Key knowledge
A classical black-hole event horizon is a causal boundary: signals from its interior cannot reach distant future observers in the exterior. In the stationary nonrotating uncharged asymptotically flat Schwarzschild black-hole model, the horizon's areal radius is r_s=2GM/c². It is not a material surface.
Values and equations
r_s=2GM/c²
- r_s
- Schwarzschild horizon areal radius m
- M
- black-hole mass kg
- G
- gravitational constant m³ kg⁻¹ s⁻²
- c
- vacuum light speed m s⁻¹
Conditions and scope
- M>0 is the black-hole mass. A mass M alone does not imply an ordinary star or diffuse mass distribution has a horizon. Rotating, charged or dynamical spacetime requires its own horizon geometry.
- This is classical general relativity; an observed dark image region is not automatically a direct measurement of this radius, and quantum emission is outside this causal model.
Sources · 1
References
Sources retain their recorded scope. A source link alone does not establish verification of every statement.
Evidence and review
Read the actual causal-boundary and radius body; narrowed the Schwarzschild assumptions and excluded source all-black-hole mass-only generalization, Newtonian escape-speed proof, universal no-radiation wording and current mass estimates.
2026-10-10 · Independent AI editorial review: All44 exact root-authored compact records, equations/variable units/conditions and140 origin edges accepted after independently reading final6/18 with bounded primary bodies and matching prior38/122 scientific fingerprints unchanged. Exact claim/edge review is distinct from combined inventory scope and separate CLE26 approval; no entire cited books or old-corpus experimental revalidation is asserted. Receipt: cosmos-completion-independent-content-and-inventory-review.1.
Entry details
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- uni-cosmos-classical-event-horizon
- Revision
- core.1
- Structured reference record
- University core expansion