The Search for Quantum Gravity

Physics faces a profound crisis as it struggles to unify two foundational theories: general relativity and quantum mechanics. While general relativity explains gravity and large-scale phenomena, quantum mechanics governs the microscopic world of particles. Despite their individual successes, these theories conflict, prompting the need for a unified framework known as quantum gravity.

One promising approach is string theory, which posits that particles are actually vibrating strings in up to 11 dimensions. However, its lack of testable predictions has spurred alternative ideas, such as loop quantum gravity. This theory envisions space and time as a network of minuscule loops, challenging the notion of time as a fundamental construct. Remarkably, loop quantum gravity suggests time might not exist at all.

When their quantum properties are precisely controlled, some ultracold atoms can resist the laws of physics that suggest everything tends towards disorder.

By Karmela Padavic-Callaghan

Researchers from the University of British Columbia, the University of Washington, and Johns Hopkins University have identified a new class of quantum states in a custom-engineered graphene structure.

Published in Nature, the study reports the discovery of topological electronic crystals in twisted bilayer–trilayer graphene, a system created by introducing a precise rotational twist between stacked two-dimensional materials.

“The starting point for this work is two flakes of graphene, which are made up of carbon atoms arranged in a honeycomb structure. The way electrons hop between the carbon atoms determines the electrical properties of the graphene, which ends up being superficially similar to more common conductors like copper,” said Prof. Joshua Folk, a member of UBC’s Physics and Astronomy Department and the Blusson Quantum Matter Institute (UBC Blusson QMI).