About the Project
A fully funded PhD opportunity to participate in the world-leading research undertaken by the EPSRC Doctoral Landscape Award at the University of Sheffield.
Supervised by Dr Steffen Gielen and Prof Elizabeth Winstanley.
The University of Sheffield is one of the leading Russell Group universities in the UK. We carry out cutting-edge research with strong links to industry. When you enrol to do a PhD with us, you will be working with world-leading academics and have access to top of the range facilities. As a PhD student you will have the opportunity to gain skills not only to conduct research, but also to take your career to the next level, whether you want to stay in academia, go into industry or the public sector, or set up your own company. You will have access to a range of training and support services to help you excel in your studies and beyond.
Project Description
General relativity is a very successful and mathematically appealing framework describing gravity as a feature of spacetime geometry. However, classical general relativity predicts the formation of singularities, where its description fails; the theory is incomplete. It is widely expected that a quantum theory of gravity is required to obtain a non-singular description.
An important question in quantum gravity is the choice of “clock” used to define time, given that in relativity time becomes observer-dependent. This project will investigate the relation between the choice of clock and the resolution of gravitational singularities (at the Big Bang or inside a black hole) through quantum effects. We will focus on the proposal that the total spacetime volume defines a good standard of time (known as unimodular time), which allows studying time evolution even in the absence of matter, or for arbitrary matter fields. In this setting, we will study different models of cosmology as well as black hole spacetimes, where the question of singularity resolution is relevant for our physical understanding of the Universe. We will also compare the results of quantum theories based on unimodular time with other clocks such as scalar fields or perfect fluids, expecting inequivalence between different choices.
The project will mostly be based on analytical calculations but it is expected that at least some numerical work will be needed as well. Good prior knowledge of general relativity and quantum field theory at MSc level is essential; some knowledge of cosmological solutions and/or black holes in general relativity would be desirable.
How to apply
Interested candidates are strongly encouraged to contact the project supervisors to discuss your interest in and suitability for the project prior to submitting your application.
Please refer to the EPSRC DLA webpage for detailed information about the EPSRC DLA and how to apply.
Applicants must ensure that they use the correct application form linked to the EPSRC DLA webpage and must submit an application for October 2027 entry. The form is unique to the EPSRC DLA. It contains the list of advertised projects from which to select, and three questions specific to the DLA.
The application deadline is 17:00 GMT 13 January 2027.
The majority of our DLA studentships will be allocated to candidates who qualify for Home fee status, in accordance with EPSRC funding regulations which place strict limits on international recruitment.
Funding Notes
The award will fund the full tuition fee and a maintenance stipend at the UKRI rate (currently £21,805 per annum) for 3.5 years, as well as a research grant to support costs associated with the project.