Black Holes
Regions where gravity is so intense that not even light escapes.
Overview
Black holes are regions where gravity is so extreme that nothing — not even light — can escape past the event horizon. They range from stellar (~5 M☉) to supermassive (billions M☉).
Why It Matters
Black holes test general relativity, power the brightest objects in the universe, and shape galaxy evolution through feedback.
Scientific Explanation
When mass compresses within its Schwarzschild radius, escape velocity exceeds c. Stellar black holes form from core-collapse supernovae. Supermassive black holes lurk in galactic centers, fed by accretion disks that outshine entire galaxies (quasars). Hawking predicted quantum evaporation — unconfirmed.
Historical Background
Michell (1783) and Laplace imagined 'dark stars.' Einstein's GR (1915) predicted black holes. Chandrasekhar's limit (1930) implied stellar collapse. First image: M87* (2019), then Sgr A* (2022).
Visual Explanation
Accretion disk heats to millions of K, bending light around the photon sphere. The shadow is not the event horizon but the lensed image of the disk behind.
Key Discoveries
- ✦ Cygnus X-1 first strong BH candidate (1971)
- ✦ LIGO detects gravitational waves from BH mergers (2015)
- ✦ Event Horizon Telescope images M87* and Sgr A*
- ✦ GW150914 opened gravitational-wave astronomy
Important Astronomers
Interactive Simulation
See how black holes bend light around their event horizons.
Black Hole Gravitational Lensing — Visual Lab
Open in Visual Lab →Related Equations
Rₛ = 2GM/c²
E=mc²
Reflection Prompt
Black holes destroy information — or do they? What does the information paradox say about reality?
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