Colloquia Archive 2023

Cosmological simulations of galaxy and structure formation have undergone rapid development over the last decade and this progress is currently accelerating. The methodology evolved from purely gravitational computations of large scale structure to full hydrodynamical simulations which include a plethora of complex baryonic physical processes. Recent successes of these simulations ...

In trying to formulate quantum theories of gravity, we need to agree on which principles of quantum mechanics and general relativity are expected as fundamental in the new theory. One of the most important properties of standard quantum mechanics is unitarity of time evolution. Quantum gravity is often expected or ...

Discussing the benefits and challenges around the development of fusion energy. The Colloquium is followed by MSc Project Presentations via the Higgs-UKAEA Plasma Physics Workshop Zoom. 14:20 MSc Project Talk - Samuli Saarelma (UKAEA) (0h25′) 14:45 MSc Project Talk - Colin Roach (UKAEA) (0h25′) 15:10 MSc Project Talk - Michael ...

I will give an overview of our current picture of two ubiquitous and compelling phenomena in high-energy physics - jets and strings. By their nature, these are not immediately evident from the Lagrangian densities or Feynman Rules of the Standard Model of Particle Physics. I will review the current state of ...

The theory of quantum computation has brought us rapid technological developments, together with remarkable improvements in how we understand quantum theory. In this talk, I shall describe the foundations of a theoretical programme to extend the quantum theory of computation beyond quantum theory itself, based on the recently proposed constructor ...

Continuum-level thermodynamic and transport properties relevant to long time and length scales can now be computed from molecular-scale interactions using multi-scale molecular dynamics (MD) simulations and Brownian dynamics (BD) simulations, along with biasing methods, such as umbrella sampling, and forward flux sampling. We demonstrate the power of these methods by ...

The holographic correspondence relates a non-gravitational theory to a gravitational theory in a higher number of space-time dimensions. In many instances of holography, the additional space dimensions are emergent: internal degrees of freedom in large matrix valued fields metamorphose into space, and their dynamics becomes re-interpreted as gravitational dynamics. This ...

The Universe we observe exhibits order on a wide range of scales, and the study of this large-scale structure provides one of our premier laboratories for fundamental physics, cosmology and astrophysics. I will describe a program to combine analytic models and numerical simulations of this large scale structure applicable to ...

The fundamental laws of physics are time-symmetric, but our macroscopic experience contradicts this. The time reversibility paradox is partly a consequence of the unpredictability of Newton’s equations of motion. We measure the dependence of the fraction of irreversible, gravitational N-body systems on numerical precision and find that it scales ...

Next Generation Quantum Theory of Atoms in Molecules (NG-QTAIM) is constructed from the eigenvectors of the Hessian of the total (real-space) charge density distribution ρ(r) field and can also use the eigenvectors of the stress tensor σ(r) and the Ehrenfest Force F(r) = -∙σ(r). NG-QTAIM can, for ...

In this talk we will introduce two research programs that aim to understand the physics of the primordial universe, leading up to the Big Bang universe. We will do so by studying the properties of primordial density perturbations that seeded the structure of the universe. In the cosmological collider physics ...

Dry and wet layers on a wall are the surface manifestation of equilibrium liquid-vapour phase transitions. Active liquids are disordered nonequilibrium systems that dissipate energy locally, able to produce phase separation in the absence of attractive interactions. We connect the emergent motility-induced separation of model active liquids with effective many-body ...

'Dark matter' (DM) is a dynamical hypothesis born from our inability to comprehend kinematic observations at the galaxy scale and larger using baryonic matter only. Astronomers have struggled with the implications of DM for galaxy formation and evolution for decades. Conversely, we've exploited observations and cosmological simulations to constrain ...

I will review recent progress on the connections between scattering amplitudes in quantum field theory and the geometry of Amplituhedron, a recently discovered mathematical object which captures particle dynamics of strong interactions. In this picture, the physics problem of predicting the outcomes of particle scattering is reformulated as the mathematical ...

The black hole information paradox — whether information escapes an evaporating black hole or not — remains one of the most longstanding mysteries of theoretical physics. The apparent conflict between validity of semiclassical gravity at low energies and unitarity of quantum mechanics has long been expected to find its resolution in a ...

Stars are often found in close binary systems, and gaseous giant planets in the solar system are surrounded by moons. Tides are raised in the bodies in these systems, and their dissipation plays a major role in shaping the orbits. The dissipation rate is very well constrained by observations. For ...

Numerical relativity simulations have allowed us to isolate and characterise the gravitational wave signals from merging black holes and neutron stars, giving us information about their parameters and astrophysical origins. The same simulations provide an opportunity to probe new effects beyond the standard model + GR paradigm, including new particles and ...

The extended mesosphere and lower thermosphere (MLT-X) region, i.e., between 60 and 200 km altitude, is the region where the Earth's atmosphere meets Space. This region is too low/high for in situ measurements with satellites/balloons. In the last few decades, MLT-X altitudes have been explored with ...