## Problem Statement for the Big Bang

Big bang cosmology has two big problems:
- The horizon problem.

All
separate, independent spacetime volumes of the early Universe must travel

at
the same velocity to create the uniform black body radiation spectrum seen in
the cosmic background radiation.
- The flatness problem.

The initial conditions must be tuned to one part in
so the mathematically

unstable solution lasts
years.

Slide 13 ran home.