Haverford College Colloquium

ADDED - Cosmological observations indicate that Universe started its life devoid of any matter or radiation: in the beginning, there was only a mysterious energy source that made the Universe expand exponentially. This cosmic growth spurt is called inflation, and it created the density variations that grew into galaxies and voids. Inflation leaves the Universe cold and empty, but the observed abundance of primordial helium requires that extremely hot radiation filled the Universe one second after inflation ended. We do not know where this radiation came from nor how the Universe evolved prior to the onset of helium production. I will summarize our (lack of) knowledge of the Universe's first second and discuss how dark matter can provide the clues we need to fill this gap in the cosmological record.