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Details of Grant 

EPSRC Reference: EP/W005441/1
Title: The Cosmological Bootstrap: Cosmological Observables from Symmetries, Locality and Unitarity
Principal Investigator: Stefanyszyn, Dr D
Other Investigators:
Researcher Co-Investigators:
Project Partners:
Department: Sch of Physics & Astronomy
Organisation: University of Nottingham
Scheme: EPSRC Fellowship
Starts: 01 October 2021 Ends: 30 September 2025 Value (£): 417,677
EPSRC Research Topic Classifications:
Cosmology Extra-Galactic Astron.&Cosmol.
EPSRC Industrial Sector Classifications:
Related Grants:
Panel History:
Panel DatePanel NameOutcome
27 Jul 2021 Stephen Hawking Fellowship - R2 Interviews Announced
26 Jul 2021 Stephen Hawking Fellowship - R2 Interviews- Panel 1 Announced
Summary on Grant Application Form
What happened during the first moments of the universe? Our current best explanation is that the universe underwent a period of "inflation" where it expanded faster than the speed of light. The primary motivation for postulating this early universe expansion is two-fold. First of all, astronomers have taught us that the universe is very flat rather than curved like a football or a saddle. Einstein's famous theory of gravity, however, causes the bending of space and so its flatness comes as a surprise. A period of early universe inflation washes out this "spatial curvature" thereby yielding a universe that looks like the one we observe. Secondly, the universe looks very similar in every direction we look in the sky. In particular, the temperature of the universe is the same in all directions with the exceptions of very tiny variations. In a theory without inflation this is very hard to explain since the universe is not old enough for these different patches of the sky to have ever been in contact. Inflation makes this very smooth temperature distribution natural as it allows these different patches in the sky to have been in contact in the far past and then pushed away to extreme distances by the very rapid expansion of inflation.

One of the primary aims of a theoretical cosmologist is to construct models of inflation that can be tested by cosmological surveys. To do this we incorporate quantum field theory which is a theoretical physicist's toolbox for computing observables. The objects that are measured by cosmological surveys are called "cosmological correlators" and they correspond to statistical correlations between matter which are imprinted on the cosmic microwave background and the distribution of galaxies. However, the computation of these observables is very cumbersome and is particularly hard when we include the effects of Einstein's theory of gravity. The primary aim of the research to be conducted during this fellowship is to derive new mathematical techniques, based on very cherished physical principles, that will allow us to compute these correlations in a very efficient manner. Our new methods will enable us to search for new generic features in cosmological observables thereby offering detailed guidance to observers at a time when there are many upcoming cosmological surveys whose primary aims are to understand the early universe.

Furthermore, early universe cosmology is the new frontier of high-energy physics. The energies that were at play during the universe's first moments are far higher than those that can be probed with traditional particle colliders. We are now entering a new era of cosmology which allows us to extract information about particle physics: the Large Hadron Collider and its jets are replaced by inflation and galaxies in what we now call "cosmological collider physics". Another aim of this research project is to improve our understanding of the structure of cosmological correlators such that they can be used as a tool to search for new particles within the cosmological collider physics programme. Many models of high-energy physics, that extend the current standard model of particle physics, predict the existence of new particles and their signals can be enhanced by inflation thereby making them detectable with future cosmology surveys. One of the most popular extensions of the standard model involves a new symmetry called "supersymmetry" that doubles the number of particles by introducing a partner for each particle of the standard model. The techniques developed during this fellowship will enable us to enhance our understanding of supersymmetry in cosmological settings and to deduce if this symmetry leaves imprints on cosmological observables.

Overall, the research to be conducted during this fellowship lies at the interface of cosmology, gravity and particle physics, and the results will be of interest to theorists and observers alike.
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Organisation Website: http://www.nottingham.ac.uk