  The cosmic dawn and epoch of reionization mark the time period in the
universe when stars, galaxies, and blackhole seeds first formed and the
intergalactic medium changed from neutral to an ionized one. Despite
substantial progress with multi-wavelength observations, astrophysical process
during this time period remain some of the least understood with large
uncertainties on our existing models of galaxy, blackhole, and structure
formation. This white paper outlines the current state of knowledge and
anticipated scientific outcomes with ground and space-based astronomical
facilities in the 2020s. We then propose a number of scientific goals and
objectives for new facilities in late 2020s to mid 2030s that will lead to
definitive measurements of key astrophysical processes in the epoch of
reionization and cosmic dawn.
