The nature of dark matter is unknown — we do not know the mass or spin of the dark matter particles. However, spin and mass can leave their signatures in the sky. In particular, when (integer spin) bosonic dark matter is sufficiently light, certain "wave-dynamical" effects of dark matter can manifest on astrophysical and even cosmological scales. I will review recent progress in exploring such phenomena including, enhancements and suppressions of structure on different scales in the cosmos, soliton formation, and in some cases, generation of macroscopic spin angular momentum density. I will then discuss observational avenues to detect or constrain these effects, and how they can shed light on the the fundamentail properties of these dark fields (especially a lower bound on their mass) and their cosmological production mechanisms.

This lecture was made possible by the William C. Ferguson Fund.