First predicted a century ago, we have recently observed gravitational waves generated by the cosmic dance of two black holes. Although the smashing of two black holes is among the most energetic processes in the universe, trying to detect their gravitational wave signal is as challenging as trying to understand whispers in a large crowd of people.
I will start my lecture by explaining how the LIGO collaboration has succeeded in picking up these elusive whispers and what we can learn from them. This ground-breaking discovery has bestowed us with a new set of ``ears'' to unravel the mysteries of our universe. In the second part of my lecture I will tell you about the gravitational wave universe, and which secrets we hope to uncover in the future with existing and planned observatories.