Whispers from the early universe

Our understanding of the universe in the era between the end of inflation and Big Bang Nucleosynthesis is rather incomplete. If detected, gravitational waves could provide a unique observational window into this intriguing era. I will discuss some sources of gravitational waves from our infant universe. In particular, I will talk about the production of gravitational waves from an era of explosive particle production after inflation, and what we can expect to learn from these waves.