Hawking Radiation

Black holes are not quite black

An interactive lesson with 6 steps, about 5 minutes: you predict, drag and solve, with instant feedback on every answer. It runs in your browser and needs JavaScript.

What you’ll learn

• Hawking temperature: $T \approx 6 \times 10^{-8}\,\text{K} \times M_\odot / M$.
• Small black holes are hot and evaporate; stellar ones are colder than the CMB and grow.
• Evaporation time grows like $M^3$.

Steps

1. A glowing horizon
2. Hotter than the sky
3. A stellar black hole
4. Twice the mass
5. The information paradox
6. Primordial black holes