Taylor Ordines, WFU graduate student — Ph. D. Defense — “Semiclassical Prediction of the Preinflationary Era, and Limits on f(R,T) Gravity” — Mentor: E. Carlson — Public talk: 10-11 AM in Olin 107.


An active subset of theoretical cosmology and astrophysics is that of research into new and interesting theories describing astrophysical and cosmological observations that are unable to be fully explained by currently accepted theories of our Universe. In this talk, I will discuss my research into two topics in this space: limits on linear fR,T gravity theories, and predictions from semiclassical gravity in the preinflationary era.

The f(R,T) gravity theories are a class of theories modifying traditional general relativity (GR) by including generic dependencies on the scalar curvature R of spacetime and on the trace of the stress-energy tensor T of matter. This modification would have a potentially measurable impact on observables, in which case comparing to observational data would allow for studying the relevance of such theories. I will present an analysis of changes to Earth’s atmosphere under a simple f(R,T) theory with linear dependence on T. Based on the accuracy of available atmospheric data, we found limits on the coefficient parametrizing the modification of |χ|≲1.8×10-13, well below theoretical values used to develop interesting deviations from GR.

Semiclassical gravity studies quantum fields on a classical curved spacetime background. I will present two studies of semiclassical gravity in the preinflationary era of our Universe. First, we analyzed whether the observed anomalous large-scale suppression in the cosmic microwave background (CMB) temperature-anisotropy power spectrum can be explained by a complete numerical solution of the inflaton field. We found, in all cases, the CMB power spectrum would indeed have suppressed large-scale moments, with important state-dependent features. Second, we investigated the common assumption that the energy density in the preinflationary era was radiation dominated. We found under the semiclassical approximation that non-negligible quantum fields do indeed have a radiation-like contribution to the energy density under certain conditions of the scale factor.


Tuesday, November 29 at 10:00am to 11:00am

Olin Physical Laboratory, 107
1834 Wake Forest Road, Winston-Salem, NC 27106

Event Type

Special Events


Academics, Physics

Target Audience

Faculty, General Public, Parents/Guests



Contact name

Candace Ring

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