  The history of the Universe and the forces that shaped it are encoded in maps
of the cosmos. From understanding these maps, we gain insights into nature that
are inaccessible by other means. Unfortunately, the connection between
fundamental physics and cosmic observables is often left to experts (and/or
computers), making the general lessons from data obscure to many particle
theorists. Fortunately, the same basic principles that govern the interactions
of particles, like locality and causality, also control the evolution of the
Universe as a whole and the manifestation of new physics in data. By focusing
on these principles, we can understand more intuitively how the next generation
of cosmic surveys will inform our understanding of fundamental physics. In
these lectures, we will explore this relationship between theory and data
through three examples: light relics ($N_{\rm eff}$) and the cosmic microwave
background (CMB), neutrino mass and gravitational lensing of the CMB, and
primordial non-Gaussianity and the distribution of galaxies. We will discuss
both the theoretical underpinnings of these signals and the real-world
obstacles to making the measurements.
