Uploaded April 2023 | Updated September 2026, 2 weeks ago
As part of the IAS-DIAS organised conference, The Amplituhedron at 10: Hidden Mathematical Structures of the Amplituhedron, Prof. Nima Arkani-Hamed (IAS, Princeton) will give a public lecture at the Royal Irish Academy on the evening of Monday 24 April.
One of the leading particle physics phenomenologists of his generation, Nima Arkani-Hamed is concerned with the relation between theory and experiment. His research has shown how the extreme weakness of gravity, relative to other forces of nature, might be explained by the existence of extra dimensions of space, and how the structure of comparatively low-energy physics is constrained within the context of string theory.
Abstract: Perhaps the most obvious fact about our universe is that it is enormously big, populated with huge objects -- stars, planets and people -- that are also all much bigger than the minuscule size of molecules, atoms and elementary particles that make up all matter. Why is this? In this talk, we will see that in trying to answer this simplest of questions -- "why is the universe big?", we are forced to confront some of the deepest mysteries confronting fundamental physics today, challenging the foundations of our understanding of spacetime, quantum mechanics and the vacuum.
As part of the IAS-DIAS organised conference, The Amplituhedron at 10: Hidden Mathematical Structures of the Amplituhedron, Prof. Nima Arkani-Hamed (IAS, Princeton) will give a public lecture at the Royal Irish Academy on the evening of Monday 24 April.
One of the leading particle physics phenomenologists of his generation, Nima Arkani-Hamed is concerned with the relation between theory and experiment. His research has shown how the extreme weakness of gravity, relative to other forces of nature, might be explained by the existence of extra dimensions of space, and how the structure of comparatively low-energy physics is constrained within the context of string theory.
Abstract: Perhaps the most obvious fact about our universe is that it is enormously big, populated with huge objects -- stars, planets and people -- that are also all much bigger than the minuscule size of molecules, atoms and elementary particles that make up all matter. Why is this? In this talk, we will see that in trying to answer this simplest of questions -- "why is the universe big?", we are forced to confront some of the deepest mysteries confronting fundamental physics today, challenging the foundations of our understanding of spacetime, quantum mechanics and the vacuum.



![DIAS 85 - STP Workshop - Matrix Membranes and Emergent Spacetime - Day 2
[2025-06-17]
(00:00:00) Simon Catterall - Sneaking up on lattice chiral fermions
(00:56:04) Masanori Hanada - From Banks-Fischler-Shenker-Susskind to Kogut-Susskind: Exponentially Accelerating Quantum Simulations
(01:56:43) David Berenstein - Staggered bosons and supersymmetry
(missing) Antal Jevicki - Finite N and BH Microstates
(02:55:44) Veselin Filev - Holographic probe branes and artificial neural networks DIAS 85 - STP Workshop - Matrix Membranes and Emergent Spacetime - Day 2](https://i.ytimg.com/vi/dTkX9P3BKt0/mqdefault.jpg)




![Multigap Topological Insulators: Non-Abelian Bands, Riemannian Geometry, Quantised Optical Responses
Speaker: Wojciech Jankowski (University of Cambridge)
Abstract: Multigap topological insulators, which fall beyond the conventional classifications of K-theory [1], are of vivid theoretical and experimental interest in condensed matter physics [2,3]. In this seminar, I will first introduce the homotopy classification of multigap topological phases with bulk topological invariants defined under PT (spacetime inversion) symmetry [3]. I will then cohomologically characterise non-Abelian bands of such phases, focusing on recently identified non-Abelian Hopf insulators with invariants underpinned by quaternion algebras [4]. Furthermore, I will discuss the momentum-space Riemannian geometry of quantum states realised by the multigap Bloch bundles, which I will connect to their physical manifestations in optical responses [5]. Finally, as quantised responses constitute a hallmark of topological phases of matter, I will show that three-dimensional multigap topological insulators can host quantised integrated non-linear shift photoconductivities [6]. I will demonstrate how the quantisation emerges from the momentum-space torsion tensors, connecting these to real Chern-Simons forms, and to virtual multiband optical transition amplitudes. Multigap Topological Insulators: Non-Abelian Bands, Riemannian Geometry, Quantised Optical Responses](https://i.ytimg.com/vi/h6-GiN_beZs/mqdefault.jpg)

