Strings, Gravity and Strongly Coupled Matter

This award funds the research activities of Professors Sera Cremonini and Timm Wrase at Lehigh University.

One of the key challenges behind understanding the beginning of the universe and the behavior of gravity at the smallest scales is that the gravitational force appears to be inherently different from the remaining interactions in nature. While the other interactions have descriptions that are consistent with quantum mechanics at the smallest scales, the gravitational interaction does not have such a description.

String theory is currently the leading framework for the unification of gravity with quantum mechanics. As part of their research, Professors Cremonini and Wrase aim to further our understanding of string theory and address longstanding fundamental questions about the basic interactions in nature and the cosmological history of our universe. In recent years it has become increasingly clear that string theory and generically any theory of gravity that is consistent with quantum mechanics will necessarily leave imprints on physics at much larger distances and lower energies.

An important part of this research is to carefully understand such imprints and how they might affect both the early and current evolution of the universe, including the nature of dark energy, and basic properties of black holes. Moreover, string theory has led to powerful techniques that can be applied to study a wide spectrum of poorly understood quantum phases of matter.

These range from the primordial soup of quarks and gluons a few millionths of a second after the Big Bang to materials with unusual electronic properties such as high-temperature superconductors. Indeed, the development of such materials will lead to new technologies which can have a significant impact on society, and is therefore in the national interest.

A key aspect of this research will exploit these novel techniques to better understand the basic mechanisms underlying such unconventional phases of matter, which is crucial to really realize their technological potential. This project also has significant broader impacts. Professors Cremonini and Wrase plan to incorporate their research developments into their teaching and education efforts on a regular basis.

They will also involve graduate students and postdocs in their research, thus providing training for junior scientists at a critical stage in their careers. Finally, they plan to engage broad and diverse audiences through frequent public lectures as well as activities aimed at K-12 students.

On a more technical level, the research projects that Professors Cremonini and Wrase will investigate will involve a number of complementary approaches to examine fundamental questions about the nature of gravity as well as various phenomenological aspects of string theory and of strongly interacting quantum systems. In particular, they will explore constraints on low-energy effective field theories and black holes by refining and extending various so-called "swampland" conjectures.

This will lead to deeper insights into string theory in general, as well as to an improved theoretical understanding of less-understood features of our own universe, like dark energy or neutrino masses. Professor Wrase will also investigate basic aspects of string phenomenology, as well as the properties of non-supersymmetric string theories and early-universe cosmology.

Professor Wrase's work on models of inflation based on alpha-attractors provides some of the most promising targets for on-going and future experiments that measure the polarization of the CMB and search for signals of large-field inflationary models. By contrast, through the use of holographic techniques, Professor Cremonini's research will shed new light on the dynamics of the strongly correlated phases of matter relevant to a wide array of materials in nature which are notoriously challenging to understand with conventional methods.

Throughout, the focus will be on identifying generic signatures of symmetry breaking in these unconventional systems. Finally, as part of a new collaborative effort, Professor Cremonini will also test some of the results and predictions of holography for non-Fermi liquids using ultracold atoms as quantum simulators.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.