Line of research overview

Quantum Gravity Phenomenology: Probing the Fundamental Nature of Spacetime

Principal Investigator: Stefano Liberati

Abstract:

Quantum gravity remains one of the most profound and elusive challenges in modern physics. It seeks to reconcile the principles of general relativity, which govern the classical behavior of gravity, with the principles of quantum mechanics that describe the behavior of subatomic particles. While theoretical efforts in this field have been extensive, empirical validation of quantum gravity remains a formidable challenge. Quantum gravity phenomenology offers a novel approach to bridge the gap between theory and experimental observations. The primary aim of this research line is to develop and implement experiments and observations that can provide empirical insights into the fundamental nature of spacetime at quantum scales.

Status of project and perspectives:

In recent years the group on QG phenomenology at IFPU has made significant progress in cataloguing, via a QG gravity model-agnostic approach, possible singularity-free black holes and cosmologies. In the first case we have studied the instabilities associated to some of these solutions and investigated the dynamical behaviour they might imply. In the second case we have catalogued possible resolution of the big bang singularity. Also, we have explored the possible phenomenology associated to Lorentz breaking in the UV both in the gravitational and matter sector.

Our proposed future objectives include:

• Testing Quantum Gravity Theories: Evaluate various quantum gravity theories (e.g., string theory, loop quantum gravity, causal set theory) by designing experiments that could detect deviations from classical predictions of gravity at both terrestrial and astrophysical scales. Quantum Gravity modified Black Holes: Investigate the quantum structure of black holes by analyzing their thermodynamics, entropy, and information paradoxes in the context of modified gravity frameworks possibly induced by quantum gravity. In particular, we intend to further explore the thermodynamical properties of black holes in the context of Lorentz breaking gravity.
• Gravitational Waves as Quantum Probes: Utilize advanced gravitational wave detectors to explore the quantum nature of spacetime by seeking deviations from classical gravitational wave predictions based on standard general relativity. Develop data analysis methods to identify the suggested quantum gravity effects in gravitational wave signals.
• Cosmological Signatures: Explore cosmological phenomena, such as primordial gravitational waves, as potential probes of the considered quantum gravity scenariios. Investigate the cosmic microwave background radiation and large-scale structure of the universe for quantum gravity imprints.

For achieving the above goals, our research line will employ a multifaceted approach, combining theoretical frameworks, analytical methods, and experimental designs. We will collaborate with physicists, astronomers, and engineers to create state-of-the-art experiments and observatories. Data analysis and simulations will be essential to interpret results and assess the implications for quantum gravity theories. The proposed research line hence represents a significant opportunity to bridge the gap between theoretical predictions and experimental validation in one of the most profound questions of modern physics.