How Hawking Radiation Works
The quantum vacuum is not empty — it constantly produces virtual particle-antiparticle pairs that annihilate almost immediately. Near a black hole's event horizon, one of a pair may fall in while the other escapes. To a distant observer, the escaping particle appears as thermal radiation emitted by the black hole. The energy comes from the black hole's mass — so the black hole loses mass and eventually evaporates.
The Temperature of a Black Hole
Hawking showed that a black hole emits radiation as a perfect blackbody at temperature T = ħc³/(8πGMk_B), where M is the black hole's mass. Stellar-mass black holes have temperatures far below the cosmic microwave background and evaporate over timescales vastly longer than the age of the universe. Only primordial micro black holes could evaporate on observable timescales.
The Information Paradox
Hawking radiation created the black hole information paradox: if a black hole forms from a structured quantum state and evaporates into thermal radiation, where did the information go? Quantum mechanics forbids information destruction. This paradox occupied theoretical physicists for 40 years. Most current theorists believe information is preserved, encoded in subtle correlations in the Hawking radiation — but the proof remains incomplete.
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What is Hawking radiation?
Hawking radiation is thermal radiation predicted to be emitted by black holes due to quantum effects near the event horizon. It arises from virtual particle-antiparticle pairs splitting near the horizon, with one particle escaping as radiation. It causes black holes to lose mass and eventually evaporate.
Has Hawking radiation been detected?
No. The temperature of Hawking radiation from any known astrophysical black hole is vastly smaller than the cosmic microwave background temperature, making it undetectable with current technology. Its detection would require either primordial micro black holes or laboratory analogs.
What is the black hole information paradox?
If a black hole forms from a specific quantum state and evaporates into featureless thermal radiation, the original information appears destroyed — violating quantum mechanical unitarity. Most theorists now believe information is preserved in subtle correlations in the Hawking radiation, but a complete proof (the 'Page curve') remains an active research area.