Gravitational wave science is about much more than just verifying the existence of the waves themselves. Long before LIGO made its first detection in 2015, the consensus amongst most physicists was that gravitational waves were real. The real power of gravitational waves is as a new tool for understanding our Universe. The early results from LIGO have already demonstrated this potential by uncovering what appears to be a new population of heavy black holes as well as determining the origin of heavy elements in the Universe through observations of a neutron star merger that was also observed by a large number of electromagnetic telescopes. Since LISA observes in an entirely separate band from LIGO, it can help answer different questions such as: “How did the massive black holes at the centers of galaxies form and grow?, “How have stars in our Milky Way evolved and died?”, and “Is general relativity the correct description of gravity and black holes?”