Independent evidence in multi-messenger astrophysics

In this paper I discuss the first “multi-messenger” observations of a binary neutron star merger and kilonova. These observations, touted as “revolutionary,” included both gravitational-wave and electromagnetic observations of a single source. I draw on analogies between astrophysics and historical sciences (e.g., paleontology) to explain the significance of this for (gravitational-wave) astrophysics. In particular, I argue that having independent lines of evidence about a target system enables the use of argumentative strategies—the “Sherlock Holmes” method and consilience—that help overcome the key challenges astrophysics faces as an observational and historical science.