If you squeeze things together, the temperature goes up. That kind of makes sense to us. The thing that doesn't make sense to us as much is that the universe, at early times, near the Big Bang, was also very, very smooth.
Si las cosas se comprimen, se eleva la temperatura. Eso tiene sentido. Lo que no parece tener tanto sentido es que el Universo, en su inicio, cerca al Big Bang, era también muy, muy homogéneo.