Introduction to Early Universe Cosmology
  Observational cosmology is in its "golden age" with a vast amount of recent
data on the distribution of matter and light in the universe. This data can be
used to probe theories of the very early universe. It is small amplitude
cosmological fluctuations which encode the information about the very early
universe and relate it to current data. Hence, a central topic in these
lectures is the "theory of cosmological perturbations", the theory which
describes the generation of inhomogeneities in the very early universe and
their evolution until the current time. I will apply this theory to three
classes of models of the very early universe. The first is "Inflationary
Cosmology", the current paradigm for understanding the early evolution of the
universe. I will review the successes of inflationary cosmology, but will also
focus on some conceptual challenges which inflationary cosmology is facing,
challenges which motivate the search for possible alternatives. I will
introduce two alternative scenarios, the "Matter Bounce" model and "String Gas
Cosmology", and I will discuss how cosmological fluctuations which can explain
the current data are generated in those models.
