Editing Particle Creation by Black Holes by Stephen Hawking (section)

==Particle Creation by Black Holes==

===What's this about?===

This paper by physicist Stephen Hawking discusses how black holes can create and emit particles, acting like hot bodies with a temperature.

===Black Holes Should Only Absorb===

Classically, black holes can only absorb particles, not emit them. But quantum effects could cause emission.

===Black Hole Temperature===

Hawking showed that black holes emit particles like a body with temperature T proportional to the surface gravity K of the black hole. For a solar mass black hole, T is tiny.

===Quantum Particles Near Horizon===

Virtual particle pairs exist near the event horizon. A negative energy particle can tunnel inside, becoming real. The positive energy particle escapes as radiation.

===Emission Causes Black Holes to Shrink===

This emission causes black holes to slowly shrink over billions of years. Tiny primordial black holes would have evaporated by now.

===As Mass Decreases, Emission Speeds Up===

As black holes shrink, they get hotter and emit faster. This can cause explosions releasing huge energy.

===Area Decreasing Violates Classical Laws===

Classically, a black hole's area can't decrease. But the emission violates this, implying negative energy flow across horizon.

===Quantum Fluctuations Cause Uncertainty===

The area decrease is due to quantum uncertainty in the horizon position, not observable negative energy.

===Emission Matches Thermal Temperature===

Hawking showed the emission matches a thermal spectrum at temperature T, supporting thermodynamic links between T, entropy, and surface gravity.

===Angular Momentum and Charge===

Rotation and charge affect T. Emission carries away angular momentum and charge. Superradiance causes enhanced emission for some modes.

===Back Reaction On the Metric===

The emission causes the black hole to evolve, not remain stationary. But the approximation works until the black hole becomes very small.

===Conclusion===

Quantum particle emission causes black holes to eventually evaporate away due to an underlying thermodynamic relationship between temperature, entropy, and surface gravity.

===Key References===

    Hawking, Nature 248, 30 (1974)
    Hawking, Communications in Mathematical Physics 43, 199 (1975)
    Bekenstein, Physical Review D 7, 2333 (1973)

See original paper for full details and references.