The Universe at Its Infancy: One Second After the Big Bang

 
Matter and radiation form the essence of what we observe with the naked eye when we peer into the heavens at night. The better we understand the dynamical history of the universe, the more we believe that the dominance of matter and radiation is a fleeting moment in the universe’s history. What conditions led to the creation of matter and radiation, and can we search for present-day relics of this time?

In this lecture, Chris Tully will discuss the earliest moments of the cosmos. The universe has expanded by a factor of over 1 billion between the present-day and the early thermal epoch known as the neutrino decoupling. We observe this dynamic in many forms: the recession of galaxies (Hubble expansion), the dim afterglow of the hot plasma epoch (cosmic microwave background) and the abundances of light elements (Big Bang nucleosynthesis). The epoch of neutrino decoupling produced the fourth pillar of confirmation: the cosmic neutrino background (CNB). These early universe relics cooled under the expansion of the universe and are sensed indirectly through the action of their diminishing thermal velocities on large-scale structure formation. Experimental advances have opened up new opportunities to directly detect the CNB, an achievement which would profoundly confront and extend the sensitivity of precision cosmology data. PTOLEMY is a novel method of 2-D target surfaces, fabricated from graphene, which forms a basis for a future large-scale relic neutrino detector. The discussion of PTOLEMY focusses on experimental challenges, recent developments and the path forward to discovery sensitivity.