Nuclear and Particle Physics Colloquium (NPPC)

Jaco de Swart

How Dark Matter Came to Matter

Abstract:
In 1974, two independent research groups in the U.S. and Estonia concluded the existence of missing mass: a yet-unseen type of matter distributed throughout the universe. Their conclusion formed the foundation of today's dark matter research. This talk is about how this conclusion was established: the history of the dark matter problem. I address how in the 1960s the radial constancy of galaxies' rotational velocity was observed. As early as the 1930s it was known that the masses of galaxies did not add up to make sense of the dynamics of galaxy clusters. I show that, although both observations are in hindsight considered evidence for the existence of dark matter, only in 1974 were these results put together as a single consistent problem. It was then that dark matter came to matter.