Music has long filled a uniquely important role in bridging human culture and biology, stretching back over millennia, and of course today provides respite and remedy in an increasingly stressful world. We do not sing alone. On land, four kinds of animals produce songs or calls: birds, frogs, mammals, and insects. Some of these animals (and fish) also do so underwater. The principal sounds such animal species make are signaling behaviors directly related to mating success and social cohesion and their ranges are molded by their forms and by their particular forest, savannah or seaside habitat.Human music also has origins, motivations and mechanisms in common with other animals. Traces of a long and ongoing history comes from archaeology, anthropology and brain studies. Evidence of a measurable impact on human biology comes from neurobiology, social psychology, and public health.
Gravitational waves (GWs) are probes of the cosmological model since, as electromagnetic waves, they travel across the largest distances in our Universe. These signals can also track generic modifications of General Relativity on large scales, especially when combined with other cosmological probes. There are several methods for using such fascinating signals to learn more about cosmology. For instance, GWs are distance indicators, and similarly to supernovae, they allow reconstructions of a distance-redshift relation when the latter can be inferred from electromagnetic counterparts emitted by the same source or known indirectly via binary population studies or galaxy catalogs. In this colloquium I will discuss some of the current methods for doing cosmological parameter estimation and tests of gravity with GWs, focusing on studies of future multi-messenger observations and on combinations of GW data with large-scale structure surveys.
