## The Quantum Black Hole

#### John Baez

Here's a picture of how we imagine a black hole in loop quantum
gravity:

The surface shown here is the event horizon.
The geometry of space outside the event horizon is described by
a `spin network'. The spin network punctures the event horizon
at various points. The area of the event horizon is quantized,
and roughly proportional to the number of punctures.

Each puncture
contributes an area of approximately 10^{-70} square meters,
so the black hole shown here is extremely small. For such a small
black hole, we expect quantum effects to be extremely important.

You can read more about this in This Week's
Finds. If you want the technical details, try
the transparencies of a talk I gave on quantum geometry and black hole entropy.

This picture was made by Kirill Krasnov and turned into gif
format by Greg Egan. I also thank Ted Bunn, Wim van Dam and
Vesselin Gueorguiev for helping me out.

baez@math.ucr.edu
© 1999 John Baez