Colloquia Archive 2021

I will describe recent work with Latham Boyle which provides a framework for a new, minimal and predictive cosmology requiring no new particles beyond those already present in the standard model (including right handed neutrinos). We start from the observation that a realistic cosmological background, dominated by radiation at early ...

The simplest approach to cosmological observables makes use of a background solution (the homogeneous and isotropic standard cosmological model) plus small, linear perturbations superposed on it. While the need to go beyond linear theory is universally recognized when dealing with cosmic structure formation, there are several other consequences of "going ...

Black holes and galaxies appear to grow in symbiosis. Non-axisymmetric features like bars, and even several embedded density waves in galaxies are necessary to exchange angular momentum and drive the gas to feed the nucleus, Feedback regulates star formation, and can be of radiative or kinetic modes in origin. Gas ...

The last decade has witnessed dramatic progress in observational black hole astronomy. At the same time, exciting new insights - but not a solution - have emerged concerning the infamous quantum black hole information paradox. The recent theoretical and experimental progress hinge on the universal critical behavior and emergent symmetries exhibited by ...

Light from stars is one of the main tools that aids in the exploration of the Universe through cosmic time. To do so a good understanding of the properties of stars in particular their masses and luminosities is required. Detailed measurements of individual stars close to us suggest that the ...

Answering questions such as "What is dark matter?" or "What happened directly after the Big Bang?" requires finding new physics, like not yet known particles or forces. Via quantum effects such new physics will contribute tiny amounts to properties of known particles and could be discovered by observing small deviations ...

Artificial Intelligence (AI) and Machine Learning (ML) were developed by humans in an attempt to aid in their innate limitations to see deep into complex data. In recent years we have seen a momentous expansion of the field, fuelled by exponential growth in computing power. While it was easy to ...

Observations over the last few years of protoplanetary discs – the birth environments of planets – have presented a startling revelation: ring and gap structures are common. The most intriguing and revolutionary of all observations is that such ring and gap features are present in extremely young discs(▯<0.5 million years ...

Microgels are soft particles individually made by cross-linked polymer networks which are nowadays widely used as a colloidal model system because of their swelling properties and their responsivity to external control parameters such temperature or pH. While extensively used as model systems in experimental, their numerical investigation lagged behind due ...

Polymer physics principles are increasingly acknowledged and applied to understand the behaviour of genome organisation and biopolymers in vivo. In spite of this they heavily rely on the assumption that polymers do not change topology (or architecture) in time, i.e. if they start as a linear chain of segments ...

Cosmology has the potential to test fundamental physics through the discovery of new particles (e.g. dark matter) and new fields that governed the Universe's expansion at early times (inflation). One of the most powerful tools available for such studies is the Baryon Acoustic Oscillation (BAO) signal. Many future ...

Modern sky surveys using large ground-based and space-borne telescopes have discovered distant stars, galaxies, and supernovae. All the rich structure in the Universe developed through gravitational amplification of primeval density fluctuations left over from the Big Bang. The standard theoretical model established by an array of recent observations accurately predicts ...

Observations suggest that the initial conditions of the history of the Universe were set by a period of superluminal expansion of space, called Cosmic Inflation. Furthermore, they also confirm that the Universe has recently entered a new inflationary era. General relativity suggests that this behaviour of space requires the dominant ...

The blooming era of ‘precision astrometry’ for Galactic studies opened by Gaia and the revolutionary beginnings of ‘gravitational wave astronomy’ enabled by LIGO truly bring the rich internal dynamics of collisional stellar systems to the centre stage. But the current interpretative picture of the role of ‘small scales’ in the ...

Cosmic inflation is widely accepted as the standard paradigm of the early universe since it not only solves the usual cosmological puzzles but also explains observed large scale inhomogeneities as originating from quantum vacuum fluctuations. However, much of its quantum properties remain obscure, and indeed, there have been recent arguments ...

The family of 2D compounds has grown almost exponentially since the discovery of graphene and so too the rapid exploration of their vast range of electronic properties. Some family members include superconductors, Mott insulators with charge-density waves, semimetals with topological properties, and transition metal dichalcogenides with spin-valley coupling. Among several ...