Associate Research Professor, CASPER, Baylor University
Quantum gravitational effects in the early Universe
The inflationary theory is consistent with all the observations carried out so far, and has provided us deep insight to the evolution of the early Universe. However, the scenario still remains as a phenomenological paradigm and suffers several conceptual issues, which are all closely related to physics in the regime where the energy scale is about the Planck energy. Solving these issues highly requires our understanding of quantum gravity. The continuing advance in high precision observations will eventually provide an opportunity to observe the quantum gravitational effects in cosmological data, whereby we are allowed to test different theories of quantum gravity. In this talk, I shall first give a basic overview over conceptual issues of the inflationary scenario, and state clearly the need of the theory of quantum gravity. Then, I shall argue that it becomes possible to test different theories of quantum gravity by directly measuring the quantum gravitational effects in the early universe from current or forthcoming cosmological data. In order to compare with observations, we need first to obtain theoretical predictions of such effects with the accuracy comparable with observations. In the past four years, we have systematically developed such a method with the upper bounds of errors no larger than 0.15%, which are accurate enough for the forthcoming generations (2015 - 2025) of observations, and is the most accurate method existing in the literature.
Dr. Tao Zhu received his Ph.D. degree from Lanzhou University in China in the field of theoretical physics in 2010. Right after that he joined the Zhejiang University of Technology in Hangzhou, China, first as an assistant professor and then an associated professor (2012 - ). In January, 2013, he joined CASPER, Baylor University as an assistant research professor. His main fields of interest include quantum theories of gravity, their effects in the early Universe, and possible detections from current and forthcoming cosmological observations.