“Nature of gravitational phase transitions”
Abstract
Phase transitions are central to understanding the behavior of matter both in our daily lives and in extreme environments like nuclear matter in neutron stars. In this talk, we will have a look at an even more abstract example, where gravity itself, rather than matter, goes through phase transitions. Namely, we will investigate how scalar fields in scalar-tensor theories, arguably the most prominent extension of Einstein’s general relativity, can change their phase in analogy to magnetization of ordinary matter. This, in turn, provides novel observational signals from neutron stars and possibly black holes, which can be used to test our fundamental theories. We will see how relatively simple tools of the Landau theory can explain our findings in a remarkable way,and also determine the characteristics of the phases such as the existence of metastable states. In other words, don’t assume this talk will be too technical just because it deals with gravity.
Reference: Nature of Phase Transitions and Metastability in Scalar-Tensor Theories, K.Ünlütürk et al. Phys.Rev.Lett. 135 (2025) 6, 061401. 10.1103/14xz-d7xf
Fethi Mübin Ramazanoğlu completed his BS degree at Massachusetts Institute of Technology and PhD at Princeton University. After postdoctoral positions at Princeton and the University of Cambridge, he joined Koç University Physics Department in 2016 where he is currently an Associate Professor. He mainly works on gravitational physics with a special interest in numerical relativity and alternative theories of gravity.
Date: 24 September 2025, Wednesday
Time: 15:30
Place: SA-240
All interested are cordially invited.