Name: Copernicus Webinar and Colloquium Series
Start: 2020-07-09T10:00:00+02:00
End: 2025-01-31T16:00:00+01:00
Location: No location set

Monday, July 6, 2020
Tuesday, July 7, 2020
Wednesday, July 8, 2020
Thursday, July 9, 2020
3:00 PM Relieving the Hubble tension with primordial magnetic fields - Levon Pogosian (Simon Fraser U.)
Relieving the Hubble tension with primordial magnetic fields
- Levon Pogosian (Simon Fraser U.)
3:00 PM - 4:00 PM
The standard cosmological model determined from the accurate cosmic microwave background measurements made by the Planck satellite implies a value of the Hubble constant H0 that is 4.2 standard deviations lower than the one determined from Type Ia supernovae. The Planck best fit model also predicts lower values of the matter density fraction Om and clustering amplitude S8 compared to those obtained from the Dark Energy Survey Year 1 data. We show that accounting for the additional inhomogeneities in the baryon density induced by primordial magnetic fields present in the plasma prior to recombination can help to solve both the H0 and the S8-Om tensions. The required field strength is just what is needed to explain the existence of galactic, cluster, and extragalactic magnetic fields without relying on dynamo amplification. Our results show clear evidence for this effect and motivate further detailed studies of primordial magnetic fields, setting several well-defined targets for future observations.
4:00 PM informal discussion/coffee time
informal discussion/coffee time
4:00 PM - 5:00 PM
Friday, July 10, 2020
Saturday, July 11, 2020
Sunday, July 12, 2020

Monday, August 3, 2020
Tuesday, August 4, 2020
Wednesday, August 5, 2020
Thursday, August 6, 2020
3:00 PM Origin of matter and gravitational wave - Hitoshi Murayama
Origin of matter and gravitational wave
- Hitoshi Murayama
3:00 PM - 4:00 PM
We exist today thanks to the asymmetry between matter and anti-matter. Its origin, however, has been one of the major mysteries in cosmology and particle physics. Arguably the leading theory called leptogenesis is that the asymmetry is generated by the decay of heavy neutrinos at the temperature above 10^9 GeV. I review this theory and point out that the gravitational wave will be an important test. If time permits, I will also discuss a different origin of the asymmetry which is also tied to the origin of dark matter, again with a gravitational wave signature.
4:00 PM informal discussion/Coffee time
informal discussion/Coffee time
4:00 PM - 5:00 PM
Friday, August 7, 2020
Saturday, August 8, 2020
Sunday, August 9, 2020

Monday, August 17, 2020
Tuesday, August 18, 2020
Wednesday, August 19, 2020
Thursday, August 20, 2020
3:00 PM alpha'-Cosmological tale: String Cosmology backgrounds from Classical String Geometry - Guilherme Franzmann
alpha'-Cosmological tale: String Cosmology backgrounds from Classical String Geometry
- Guilherme Franzmann
3:00 PM - 4:00 PM
In this talk, I intend to give a pedagogical, nonetheless biased, introduction to String Cosmology. After briefly reviewing the Lambda-CDM model and motivating inflation, we will remind ourselves that early universe cosmology remains singular and waiting for alternatives. That will be our cue to consider string theory to define our gravity sector and string thermodynamics to define our matter sector. We will learn how that doesn't work, unless we consider more string corrections (in fact, infinity of them!). Once we are stringy enough, we will be able to build a full cosmological model that is non-singular and already poses itself as an alternative to inflation at the background level.
4:00 PM informal discussion/coffee time
informal discussion/coffee time
4:00 PM - 5:00 PM
Friday, August 21, 2020
Saturday, August 22, 2020
Sunday, August 23, 2020

Monday, September 14, 2020
Tuesday, September 15, 2020
Wednesday, September 16, 2020
6:00 PM Signals of a Quantum Universe - Daniel Green
Signals of a Quantum Universe
- Daniel Green
6:00 PM - 7:00 PM
The idea that structure in the universe was created from quantum mechanical vacuum fluctuations during inflation is very compelling, but unproven. Testing this proposal is challenging because the universe we observe is effectively classical. I will explain the origin of this challenge and how it can be circumvented if we observe equilateral primordial non-Gaussianity. In particular, we will see that the absence of an accompanying folded non-Gaussian signal is only possible (assuming locality) with quantum vacuum fluctuations.
7:00 PM informal discussion/coffee time
informal discussion/coffee time
7:00 PM - 8:00 PM
Thursday, September 17, 2020
Friday, September 18, 2020
Saturday, September 19, 2020
Sunday, September 20, 2020

Monday, October 5, 2020
Tuesday, October 6, 2020
Wednesday, October 7, 2020
Thursday, October 8, 2020
10:00 AM Probing extremely small-scale primordial perturbations by gravitational waves - Suyama Teruaki
Probing extremely small-scale primordial perturbations by gravitational waves
- Suyama Teruaki
10:00 AM - 11:00 AM
According to the theory of inflation, the primordial perturbations existed over a wide range of length scales from meter size at the smallest scale up to at least the Hubble horizon on the largest scale. Stochastic gravitational waves have been attracting a lot of interest recently as a new powerful probe of the primordial perturbations on very small scales. In this talk, I will give a brief overview in this field and present a recent search for such gravitational waves by using LIGO O2 data and its implications.
Friday, October 9, 2020
Saturday, October 10, 2020
Sunday, October 11, 2020

Monday, October 12, 2020
Tuesday, October 13, 2020
Wednesday, October 14, 2020
Thursday, October 15, 2020
8:00 PM Detecting the thermal effect of acceleration in an Analog system. - Bill Unruh
Detecting the thermal effect of acceleration in an Analog system.
- Bill Unruh
8:00 PM - 9:00 PM
Given the intimate connection of gravity and its dependence on the changing flow of time from place to place, it is surprizing that General Relativistic effects can be modeled in other systems. In 1981 I showed that even the Hawking effect has analogies in other systems, which has spawned an active experimental effort in the past few decades. A harder case has turned out to to model the thermal effect that an accelerated detector in the vacuum. Following Bell and Leinaas in 1983, we showed that a circularly accelerated detector can also show a themal effect. This talks will present a way of implimenting a broad band detector of the quantum fluctuations in a BEC which may also be just realisable with an interferometric detector by borrowing techniques from LIGO, with the interferometer in frequency space rather than in real space.
Friday, October 16, 2020
Saturday, October 17, 2020
Sunday, October 18, 2020

Monday, October 19, 2020
Tuesday, October 20, 2020
Wednesday, October 21, 2020
Thursday, October 22, 2020
7:00 PM Pulsar Timing Arrays: The Next Window to Open on the Gravitational-Wave Universe - Chiara Mingarelli
Pulsar Timing Arrays: The Next Window to Open on the Gravitational-Wave Universe
- Chiara Mingarelli
7:00 PM - 8:00 PM
Galaxy mergers are a standard aspect of galaxy formation and evolution, and most (likely all) large galaxies contain supermassive black holes. As part of the merging process, the supermassive black holes should in-spiral together and eventually merge, generating a background of gravitational radiation in the nanohertz to microhertz regime. An array of precisely timed pulsars spread across the sky can form a galactic-scale gravitational wave detector in the nanohertz band. I describe the current efforts to develop and extend the pulsar timing array concept, together with recent limits which have emerged from international efforts to constrain astrophysical phenomena at the heart of supermassive black hole mergers.
Friday, October 23, 2020
Saturday, October 24, 2020
Sunday, October 25, 2020

Monday, October 26, 2020
Tuesday, October 27, 2020
Wednesday, October 28, 2020
3:00 PM The status of cosmological tensions after Planck - Silvia Galli (IAP)
The status of cosmological tensions after Planck
- Silvia Galli (IAP)
3:00 PM - 4:00 PM
The results of the ESA Planck satellite have enabled extrordinary progress in our understanding of the universe in the past few years. Furthermore, its (sub)-percent measurement of cosmological parameters allowed us to discover a few inconsistencies with other astrophysical probes, which might point towards a crisis of the current standard model of cosmology. In this talk, I will review some of these inconsistencies and highlight the prospects for the future.
4:00 PM informal discussion
informal discussion
4:00 PM - 5:00 PM
Thursday, October 29, 2020
Friday, October 30, 2020
Saturday, October 31, 2020
Sunday, November 1, 2020

Monday, November 9, 2020
Tuesday, November 10, 2020
Wednesday, November 11, 2020
Thursday, November 12, 2020
Friday, November 13, 2020
Saturday, November 14, 2020
Sunday, November 15, 2020

Monday, November 16, 2020
Tuesday, November 17, 2020
3:00 PM Exploring the early universe with the stochastic background of induced gravitational waves - Guillem Domenech (Padova)
Exploring the early universe with the stochastic background of induced gravitational waves
- Guillem Domenech (Padova)
3:00 PM - 4:00 PM
I will discuss the current status of the secondary gravitational waves induced by the curvature perturbation and why they might be an important source of the cosmological stochastic gravitational wave background. As a practical example, I will use the latest NANOGrav results on the stochastic background of nanohertz gravitational waves to constrain the equation of state parameter of the early universe and the mass of the associated primordial black holes.
Wednesday, November 18, 2020
Thursday, November 19, 2020
Friday, November 20, 2020
Saturday, November 21, 2020
Sunday, November 22, 2020

Monday, November 23, 2020
4:00 PM New Physics and the Black Hole Mass Gap - Djuna Croon (TRIUMF)
New Physics and the Black Hole Mass Gap
- Djuna Croon (TRIUMF)
4:00 PM - 5:00 PM
In this talk I will demonstrate the potential of the black hole mass gap to probe new physics. The mass gap, in which no black holes can be formed, is a standard prediction of stellar structure theory. I will show that new physics that couples to the Standard Model can act as an additional source of energy loss in the cores of heavy stars, dramatically altering their evolution, resulting in large shifts of the gap. I will also discuss how new contributions may modify the stellar equation of state. The gravitational wave observations by the LIGO/Virgo collaboration will bring the edges of the black hole mass gap in sight in the coming years, making this a promising novel probe of new physics.
Tuesday, November 24, 2020
Wednesday, November 25, 2020
Thursday, November 26, 2020
Friday, November 27, 2020
Saturday, November 28, 2020
Sunday, November 29, 2020

Monday, December 7, 2020
Tuesday, December 8, 2020
Wednesday, December 9, 2020
Thursday, December 10, 2020
Friday, December 11, 2020
10:00 AM A look at axion inflation in string theory - Alexander Westphal (DESY)
A look at axion inflation in string theory
- Alexander Westphal (DESY)
10:00 AM - 11:00 AM
We will take a look at axion inflation in string theory, taking a somewhat eclectic approach guided by some mechanism classes and (semi-)explicit examples. Looking at models with either 1 or 2 axions, we will argue that (up to manifestly tuning for small-field models) inflation can arise from 2 different mechanisms - either monodromy, or hybrid inflation. Cautiously incorporating both known limits of top-down theory knowledge as well as bottom-up ‘effective quantum gravity’ conjectural constraints, should lead to a ‘theory error blob’ of CMB observable predictions describing the ‘mechanism equivalence class’. We outline this using harmonic hybrid inflation as a representative of 2-axion hybrid inflation, and then describe a systematic method of propagating the ‘theory error’ to observable predictions using machine learning and information geometry
Saturday, December 12, 2020
Sunday, December 13, 2020

Monday, December 14, 2020
3:00 PM Black Holes Are Finally in Vogue - Abraham (Avi) Loeb (Harvard University)
Black Holes Are Finally in Vogue
- Abraham (Avi) Loeb (Harvard University)
3:00 PM - 4:00 PM
With black holes, what you see is not what you get. They are extreme structures of spacetime that represent the ultimate prison, from where even light cannot escape. After decades of being a subject of mathematical interest, recently black holes became a topic of direct observational studies, for which two Nobel prizes were awarded over the past three years. I will describe some of the most exciting frontiers in current multi-messenger studies of astrophysical black holes.
Tuesday, December 15, 2020
Wednesday, December 16, 2020
Thursday, December 17, 2020
Friday, December 18, 2020
Saturday, December 19, 2020
Sunday, December 20, 2020

Monday, December 21, 2020
Tuesday, December 22, 2020
Wednesday, December 23, 2020
Thursday, December 24, 2020
Friday, December 25, 2020
Saturday, December 26, 2020
Sunday, December 27, 2020

Monday, December 28, 2020
Tuesday, December 29, 2020
Wednesday, December 30, 2020
Thursday, December 31, 2020
Friday, January 1, 2021
Saturday, January 2, 2021
Sunday, January 3, 2021

Monday, January 4, 2021
Tuesday, January 5, 2021
Wednesday, January 6, 2021
Thursday, January 7, 2021
Friday, January 8, 2021
Saturday, January 9, 2021
Sunday, January 10, 2021

Monday, January 11, 2021
Tuesday, January 12, 2021
1:00 PM Quantum fluctuations and new instantons - Viatcheslav Mukhanov (LMU)
Quantum fluctuations and new instantons
- Viatcheslav Mukhanov (LMU)
1:00 PM - 2:00 PM
I will discuss how quantum fluctuations modify the Coleman theory of the decay of false vacuum
Wednesday, January 13, 2021
Thursday, January 14, 2021
Friday, January 15, 2021
Saturday, January 16, 2021
Sunday, January 17, 2021

Monday, January 18, 2021
Tuesday, January 19, 2021
Wednesday, January 20, 2021
Thursday, January 21, 2021
Friday, January 22, 2021
Saturday, January 23, 2021
Sunday, January 24, 2021

Monday, February 8, 2021
Tuesday, February 9, 2021
3:00 PM Quantum gravity predictions for cosmology: from the beginning to dynamical dark energy. - Christof Wetterich (Universitat Heidelberg)
Quantum gravity predictions for cosmology: from the beginning to dynamical dark energy.
- Christof Wetterich (Universitat Heidelberg)
3:00 PM - 4:00 PM
Wednesday, February 10, 2021
Thursday, February 11, 2021
Friday, February 12, 2021
Saturday, February 13, 2021
Sunday, February 14, 2021

Monday, February 15, 2021
Tuesday, February 16, 2021
Wednesday, February 17, 2021
Thursday, February 18, 2021
10:00 AM Axions, Dark Matter, and the Primordial Density Perturbation - Takeshi Kobayashi (Nagoya University)
Axions, Dark Matter, and the Primordial Density Perturbation
- Takeshi Kobayashi (Nagoya University)
10:00 AM - 11:00 AM
I will present new ideas about how the QCD axion or axion-like particles can make up the dark matter of our universe, and/or explain the origin of the primordial density perturbation. For axion dark matter, I will introduce a novel production mechanism that invokes a kinetic mixing between the axion and the inflaton. I will show that this mechanism opens up new windows in the axion parameter space, where conventional scenarios such as vacuum misalignment cannot work. The impact of primordial electromagnetic fields on the axion window will also be discussed. For the density perturbation, I will demonstrate that an axion-like particle coupled to a new confining gauge group is a perfect candidate of a curvaton, and that the resulting density perturbation has distinct signatures that are testable in upcoming experiments.
Friday, February 19, 2021
Saturday, February 20, 2021
Sunday, February 21, 2021

Monday, February 22, 2021
Tuesday, February 23, 2021
2:00 PM Gravitational waves from first-order phase transition during inflation - Haipeng An (Tsinghua University)
Gravitational waves from first-order phase transition during inflation
- Haipeng An (Tsinghua University)
2:00 PM - 3:00 PM
I will talk about the properties of the gravitational wave (GW) signals produced by first-order phase transitions during the inflation era. I will show that the power spectrum of the GW oscillates with its wave number. This oscillatory feature corresponds to the instantaneous nature of the first-order phase transition. I will also show that we can get information about how the universe evolves during and after inflation from the slopes of different parts of the spectrum. I will also present simple models that first-order phase transition can happen and finish during inflation. I will also show that this signal can be observed directly by future terrestrial and spatial GW detectors and through the B-mode spectrum in CMB.
Wednesday, February 24, 2021
Thursday, February 25, 2021
Friday, February 26, 2021
Saturday, February 27, 2021
Sunday, February 28, 2021

Monday, March 22, 2021
Tuesday, March 23, 2021
Wednesday, March 24, 2021
Thursday, March 25, 2021
2:00 PM Decoding and bootstrapping cosmological fluctuations - Guilherme L. Pimentel (Leiden U.)
Decoding and bootstrapping cosmological fluctuations
- Guilherme L. Pimentel (Leiden U.)
2:00 PM - 3:00 PM
I will review our current understanding of the initial conditions of the universe, and describe what information is available from current and future measurements of cosmological correlation functions. Then I will describe a new method to compute and constrain the possible shapes of those correlation functions, assuming they were generated during inflation. This ``cosmological bootstrap” draws inspiration from the modern scattering amplitudes program in flat space, as well as the conformal bootstrap of phase transitions. After discussing primordial scalar fluctuations, I will also explain how the consistent propagation of gravitational waves imposes further constraints on the structure of spinning primordial correlators.
Friday, March 26, 2021
Saturday, March 27, 2021
Sunday, March 28, 2021

Monday, April 12, 2021
Tuesday, April 13, 2021
3:00 PM What the Hubble tension really is and how (not) to solve it - Sunny Vagnozzi (Cambridge University)
What the Hubble tension really is and how (not) to solve it
- Sunny Vagnozzi (Cambridge University)
3:00 PM - 4:00 PM
Despite being arguably one of the hottest topics in the recent literature, there are several widely spread misconceptions concerning what the Hubble tension really is. Moreover, leaving these misconceptions aside, no compelling model to solve the Hubble tension has been found so far, despite a huge number of attempts (and false alarms). I will begin by explaining what the Hubble tension really is, presenting three different interpretations in order of increasing "correctness". I will then discuss why so many proposed models have failed so far, and what in my opinion is the way forward towards constructing a realistic solution to the tension. I will close by presenting the "10 commandments" which I believe every "Hubble hunter" should abide by.
Wednesday, April 14, 2021
Thursday, April 15, 2021
Friday, April 16, 2021
Saturday, April 17, 2021
Sunday, April 18, 2021

Monday, April 19, 2021
Tuesday, April 20, 2021
3:00 PM New Probes of Large-Scale Structure - Scott Dodelson (Carnegie Mellon U.)
New Probes of Large-Scale Structure
- Scott Dodelson (Carnegie Mellon U.)
3:00 PM - 4:00 PM
Progress in cosmology over the past few decades has been quantified by the extent to which we can accurately measure “two-point functions” such as the power spectrum of galaxies; the shear-shear- correlation function; galaxy-galaxy lensing; and most famously the C_l’s of the anisotropies in the cosmic microwave background. New statistics are emerging though that offer potential to infer even more information about the universe. I will open by asking your opinions about what information is most important that is not listed above. Then, I will give my opinion and share some proposals for extending this relatively new class of statistics to learn about the large-scale structure of the universe.
Wednesday, April 21, 2021
Thursday, April 22, 2021
Friday, April 23, 2021
Saturday, April 24, 2021
Sunday, April 25, 2021

Monday, April 26, 2021
Tuesday, April 27, 2021
Wednesday, April 28, 2021
Thursday, April 29, 2021
3:00 PM Fundamental Physics from Gravitational Waves - John Ellis (King's College London)
Fundamental Physics from Gravitational Waves
- John Ellis (King's College London)
3:00 PM - 4:00 PM
Following the direct discovery of gravitational waves (GWs) by LIGO and Virgo, there are many opportunities to probe fundamental physics using GWs. These include using GWs from astrophysical sources to constrain the graviton mass and search for Lorentz violation, as well as searching for GWs from dark matter in merging neutron stars, from first-order phase transitions in the early Universe, and from loops of cosmic strings, as may be hinted by recent data from the NANOGrav pulsar timing array. The roles that could be played by atom interferometers measuring GWs in the mid-frequency band between LIGO/Virgo and LISA will be highlighted.
Friday, April 30, 2021
Saturday, May 1, 2021
Sunday, May 2, 2021

Monday, May 3, 2021
Tuesday, May 4, 2021
3:00 PM Black Holes, Unscripted - Niayesh Afshordi (Perimeter Institute)
Black Holes, Unscripted
- Niayesh Afshordi (Perimeter Institute)
3:00 PM - 4:00 PM
Black Holes occupy a special place in the fascination of astronomers and physicists. From the most speculative mathematical physicist to the most sensible radio astronomer, everyone has their own narrative of what lies within a black hole, based on their own preconceptions. This is in contrast to the more empirical and agnostic approach that we take in studying (almost) everything else in physics. As an alternative, I will outline what I consider to be a physical roadmap to unravelling what lies within black holes.
Wednesday, May 5, 2021
Thursday, May 6, 2021
Friday, May 7, 2021
Saturday, May 8, 2021
Sunday, May 9, 2021

Monday, May 17, 2021
Tuesday, May 18, 2021
3:00 PM Quantum collapse models and cosmic inflation - Jerome Martin (IAP)
Quantum collapse models and cosmic inflation
- Jerome Martin (IAP)
3:00 PM - 4:00 PM
Attempts to apply quantum collapse theories to Cosmology and cosmic inflation are reviewed. These attempts are motivated by the fact that the theory of cosmological perturbations of quantum-mechanical origin suffers from the single outcome problem, which is a modern incarnation of the quantum measurement problem, and that collapse models can provide a solution to these issues. Since inflationary predictions can be very accurately tested by cosmological data, this also leads to constraints on collapse models. These constraints are derived in the case of Continuous Spontaneous Localization (CSL) and are shown to be of unprecedented efficiency.
Wednesday, May 19, 2021
Thursday, May 20, 2021
Friday, May 21, 2021
Saturday, May 22, 2021
Sunday, May 23, 2021

Monday, May 24, 2021
Tuesday, May 25, 2021
2:00 PM Minimalism in modified gravity - Shinji Mukohyama (YITP)
Minimalism in modified gravity
- Shinji Mukohyama (YITP)
2:00 PM - 3:00 PM
It is generally believed that modification of general relativity inevitably introduces extra physical degree(s) of freedom. In this talk I argue that this is not the case by constructing modified gravity theories with two local physical degrees of freedom. After classifying such theories into two types, I show explicit examples and discuss their cosmology and phenomenology, such as possible amelioration of the H0 tension and stable massive gravity/bigravity cosmology.
Wednesday, May 26, 2021
Thursday, May 27, 2021
Friday, May 28, 2021
Saturday, May 29, 2021
Sunday, May 30, 2021

Monday, May 31, 2021
Tuesday, June 1, 2021
3:00 PM Probing high-scale new physics with modulated reheating - Zhong-Zhi Xianyu (Tsinghua University)
Probing high-scale new physics with modulated reheating
- Zhong-Zhi Xianyu (Tsinghua University)
3:00 PM - 4:00 PM
Scalar fields with spatially varying background could modulate the reheating process, thereby leaving their imprints in the density perturbations. In this talk we discuss two scenarios using this mechanism to probe physics at very high scales. First, we introduce a “cosmological Higgs collider” where the SM-Higgs-modulated reheating allows us to discover heavy particles and to measure their Higgs couplings in the squeezed primordial bispectrum. Second, we explain that the modulated reheating can act as a “cosmic microscope” that enlarges the small-scale preheating dynamics to CMB scales, providing us a chance to learn non-perturbative dynamics of the preheating.
Wednesday, June 2, 2021
Thursday, June 3, 2021
Friday, June 4, 2021
Saturday, June 5, 2021
Sunday, June 6, 2021

Monday, June 7, 2021
Tuesday, June 8, 2021
3:00 PM Indirect detection of gravitons through quantum entanglement - Sugumi Kanno (Kyushu University)
Indirect detection of gravitons through quantum entanglement
- Sugumi Kanno (Kyushu University)
3:00 PM - 4:00 PM
We propose an experiment that the entanglement between two macroscopic mirrors suspended at the end of an equal-arm interferometer is destroyed by the noise of gravitons through bremsstrahlung. By calculating the correlation function of the noise, we obtain the decoherence time from the decoherence functional. We estimate that the decoherence time induced by the noise of gravitons in squeezed states stemming from inflation is approximately 20 seconds for 40 km long arms and 40 kg mirrors. Our analysis shows that observation of the decoherence time of quantum entanglement has the potential to detect gravitons indirectly. This indirect detection of gravitons would give strong evidence of quantum gravity.
Wednesday, June 9, 2021
Thursday, June 10, 2021
Friday, June 11, 2021
Saturday, June 12, 2021
Sunday, June 13, 2021

Monday, June 14, 2021
Tuesday, June 15, 2021
3:00 PM A stringy perspective on the coincidence problem - Antonio Padilla (Nottingham University)
A stringy perspective on the coincidence problem
- Antonio Padilla (Nottingham University)
3:00 PM - 4:00 PM
The cosmological coincidence problem is the question of why now? Why do we live at the dawn of dark energy domination, when the energy density of dark matter and dark energy are roughly comparable? In this talk, I will describe how the problem is significantly alleviated, if not entirely solved, in generic string theory models of dark energy.
Wednesday, June 16, 2021
Thursday, June 17, 2021
3:00 PM [Colloquium] Black Hole Thermodynamics, Then and Now - Edward Witten (IAS)
[Colloquium] Black Hole Thermodynamics, Then and Now
- Edward Witten (IAS)
3:00 PM - 4:00 PM
Friday, June 18, 2021
Saturday, June 19, 2021
Sunday, June 20, 2021

Monday, June 21, 2021
Tuesday, June 22, 2021
3:00 PM Self-Organised Localisation - Tevong You (CERN)
Self-Organised Localisation
- Tevong You (CERN)
3:00 PM - 4:00 PM
We describe a new phenomenon in quantum cosmology: self-organised localisation. When the fundamental parameters of a theory are functions of a scalar field subject to large fluctuations during inflation, quantum phase transitions can act as dynamical attractors. As a result, the theory parameters are probabilistically localised around the critical value and the Universe finds itself at the edge of a phase transition. We illustrate how self-organised localisation could account for the observed near-criticality of the Higgs self-coupling, the naturalness of the Higgs mass, or the smallness of the cosmological constant.
Wednesday, June 23, 2021
Thursday, June 24, 2021
Friday, June 25, 2021
Saturday, June 26, 2021
Sunday, June 27, 2021

Monday, July 5, 2021
Tuesday, July 6, 2021
3:00 PM A higher dimensional view on quantum cosmology - Thomas Van Riet
A higher dimensional view on quantum cosmology
- Thomas Van Riet
3:00 PM - 4:00 PM
Fundamental questions in cosmology, such as understanding the Big Bang, the cosmic hierarchy problem and boundary conditions for the wave function of the universe, should be possible to address explicitly in (toy?) models that are UV complete. Inspired from string theory I will discuss the role of extra dimensions in all these issues and show that indeed with some varying degree of precision the physics of extra dimensions provides answers. For instance; in a very natural suggestion by Banerjee et al to realise a de Sitter cosmology from string theory, I will explain how Vilenkin's tunneling wave function is selected as the unique boundary condition for the wave function of the universe.
Wednesday, July 7, 2021
Thursday, July 8, 2021
Friday, July 9, 2021
Saturday, July 10, 2021
Sunday, July 11, 2021

Monday, August 16, 2021
Tuesday, August 17, 2021
Wednesday, August 18, 2021
Thursday, August 19, 2021
Friday, August 20, 2021
Saturday, August 21, 2021
Sunday, August 22, 2021

Monday, August 23, 2021
Tuesday, August 24, 2021
Wednesday, August 25, 2021
Thursday, August 26, 2021
Friday, August 27, 2021
Saturday, August 28, 2021
Sunday, August 29, 2021

Monday, September 27, 2021
Tuesday, September 28, 2021
Wednesday, September 29, 2021
Thursday, September 30, 2021
Friday, October 1, 2021
3:00 PM Emergent Cosmology from the BFSS Matrix Model - Suddhasattwa Brahma (U. Edinburgh)
Emergent Cosmology from the BFSS Matrix Model
- Suddhasattwa Brahma (U. Edinburgh)
3:00 PM - 4:20 PM
The BFSS matrix model is a proposed non-perturbative definition of M-theory in which space is emergent. In this talk, I shall present a new paradigm of early-universe cosmology in the context of the BFSS theory. Specifically, I will show that matrix theory leads to an emergent non-singular cosmology which, at late times, can be described by an expanding phase of Standard Big Bang cosmology. Crucially, the thermal fluctuations in the emergent phase source an approximately scale-invariant spectrum of scalar perturbations and a scale-invariant spectrum of gravitational waves. Hence, this model leads to a successful scenario for the origin of perturbations responsible for the currently observed structure in the universe while providing a consistent UV-complete description.
Saturday, October 2, 2021
Sunday, October 3, 2021

Monday, October 4, 2021
Tuesday, October 5, 2021
Wednesday, October 6, 2021
Thursday, October 7, 2021
Friday, October 8, 2021
3:00 PM Gauge invariant formulation of the induced gravitational waves - Atsuhisa Ota (Hong Kong University of Science and Technology)
Gauge invariant formulation of the induced gravitational waves
- Atsuhisa Ota (Hong Kong University of Science and Technology)
3:00 PM - 4:40 PM
The gauge dependence of the second order induced gravitational waves are widely recognized issue since GWs should be physical observable. While there have been several studies about the gauge dependence, I will talk about a new idea to solve the issue. I revisited the definition of nonlinear tensor modes and their gauge transformation from a covariant perspective and find a way to properly define the gauge invariant energy density of the induced GWs.
Saturday, October 9, 2021
Sunday, October 10, 2021

Monday, October 11, 2021
Tuesday, October 12, 2021
3:00 PM Unlocking Dark Matter Physics out of Astrophysical Data Sets - Cora Dvorkin (Harvard University)
Unlocking Dark Matter Physics out of Astrophysical Data Sets
- Cora Dvorkin (Harvard University)
3:00 PM - 4:20 PM
Cosmological observations and galaxy dynamics seem to imply that 84% of all matter in the universe is composed of dark matter, which is not accounted for by the Standard Model of particles. The particle nature of dark matter is one of the most intriguing puzzles of our time. The wealth of knowledge which is and will soon be available from astrophysical surveys will reveal new information about our universe. I will discuss how we can use new and complementary data sets to improve our understanding of the particle nature of dark matter both at large and small scales.
Wednesday, October 13, 2021
Thursday, October 14, 2021
Friday, October 15, 2021
Saturday, October 16, 2021
Sunday, October 17, 2021

Monday, December 6, 2021
Tuesday, December 7, 2021
3:00 PM Testing the equivalence principle on cosmological scales - Camille Bonvin (Geneva U.)
Testing the equivalence principle on cosmological scales
- Camille Bonvin (Geneva U.)
3:00 PM - 4:20 PM
The weak equivalence principle is one of the cornerstones of general relativity. Its validity has been tested with impressive precision in the Solar System, with experiments involving baryonic matter and light. However, on cosmological scales and when dark matter is concerned, the validity of this principle is still unknown. In this talk I will show how relativistic effects in the large-scale structure can be used to test whether dark matter obeys the weak equivalence principle. I will present forecasts for this new test of gravity for future surveys like the SKA.
Wednesday, December 8, 2021
Thursday, December 9, 2021
Friday, December 10, 2021
Saturday, December 11, 2021
Sunday, December 12, 2021

Monday, December 13, 2021
Tuesday, December 14, 2021
Wednesday, December 15, 2021
Thursday, December 16, 2021
3:15 PM Testing inflation with small-scale anisotropies - Ema Dimastrogiovanni (Groningen U. and New South Wales U.)
Testing inflation with small-scale anisotropies
- Ema Dimastrogiovanni (Groningen U. and New South Wales U.)
3:15 PM - 4:35 PM
Inflation predicts a stochastic background of gravitational waves. In this talk I will discuss how anisotropies in the gravitational wave energy density can be a powerful tool in characterizing the inflationary gravitational wave background and potentially distinguishing it from backgrounds due to other sources.
Friday, December 17, 2021
Saturday, December 18, 2021
Sunday, December 19, 2021

Monday, December 20, 2021
Tuesday, December 21, 2021
Wednesday, December 22, 2021
Thursday, December 23, 2021
Friday, December 24, 2021
Saturday, December 25, 2021
Sunday, December 26, 2021

Monday, December 27, 2021
Tuesday, December 28, 2021
Wednesday, December 29, 2021
Thursday, December 30, 2021
Friday, December 31, 2021
Saturday, January 1, 2022
Sunday, January 2, 2022

Monday, January 3, 2022
Tuesday, January 4, 2022
Wednesday, January 5, 2022
Thursday, January 6, 2022
Friday, January 7, 2022
Saturday, January 8, 2022
Sunday, January 9, 2022

Monday, January 17, 2022
Tuesday, January 18, 2022
3:00 PM Testing the cosmological principle - Roya Mohayaee (Paris, Inst. Astrophys.)
Testing the cosmological principle
- Roya Mohayaee (Paris, Inst. Astrophys.)
3:00 PM - 4:20 PM
Our local Universe is anisotropic. On the contrary the CMB indicates that the early Universe was isotropic. A convergence between the two is expected in the standard model of cosmology. In this talk, I explore various observational probes to search for the cross-over between these two domains.
Wednesday, January 19, 2022
Thursday, January 20, 2022
Friday, January 21, 2022
Saturday, January 22, 2022
Sunday, January 23, 2022

Monday, January 31, 2022
Tuesday, February 1, 2022
Wednesday, February 2, 2022
3:00 PM Aspects of Light Scalar Dark Matter - Mark Hertzberg (Tufts University)
Aspects of Light Scalar Dark Matter
- Mark Hertzberg (Tufts University)
3:00 PM - 4:20 PM
I discuss various aspects of very light scalar dark matter, including axions. I begin by reviewing the properties of light scalar dark matter in superfluid condensates, and the relation to classical field theory. I review how such condensates are spatially localized clumps, which may be present in the galaxy. I then discuss the interesting possibility of parametric resonance of scalar axion clumps into electromagnetic waves, after mergers, which may leave an astrophysical signature. I also critically examine whether ultra-light scalars can resolve the core-cusp problem at the center of galaxies. I discuss the rate of decoherence of dark matter scalars that are in non-trivial quantum states. Finally, I examine the theoretical consistency of scalar dark matter models with non-standard interactions that address novel galactic features.
Thursday, February 3, 2022
Friday, February 4, 2022
Saturday, February 5, 2022
Sunday, February 6, 2022

Monday, February 14, 2022
Tuesday, February 15, 2022
3:00 PM Covariant formulation of non-equilibrium thermodynamics in General Relativity: Cosmic Acceleration from First Principles - Juan Garcia-Bellido
Covariant formulation of non-equilibrium thermodynamics in General Relativity: Cosmic Acceleration from First Principles
- Juan Garcia-Bellido
3:00 PM - 4:20 PM
Wednesday, February 16, 2022
Thursday, February 17, 2022
Friday, February 18, 2022
Saturday, February 19, 2022
Sunday, February 20, 2022

Monday, February 28, 2022
Tuesday, March 1, 2022
3:00 PM The Hubble tension and new physics at the eV scale: The path to New Early Dark Energy - Martin Sloth (CP3, University of Southern Denmark)
The Hubble tension and new physics at the eV scale: The path to New Early Dark Energy
- Martin Sloth (CP3, University of Southern Denmark)
3:00 PM - 4:20 PM
I will discuss the possibility that the Hubble tension is the signature of a fast triggered phase transition in the dark sector. Such a phase transition is called New Early Dark Energy (NEDE) and must have taken place just before recombination at the eV scale to resolve the tension fully. After discussing the cosmological NEDE phase transition, I will discuss the details of possible particle physics realizations.
Wednesday, March 2, 2022
Thursday, March 3, 2022
Friday, March 4, 2022
Saturday, March 5, 2022
Sunday, March 6, 2022

Monday, March 7, 2022
Tuesday, March 8, 2022
3:00 PM Probing the Early Universe with Gravitational Waves - Matteo Fasiello (Madrid, IFT & ICG, Portsmouth)
Probing the Early Universe with Gravitational Waves
- Matteo Fasiello (Madrid, IFT & ICG, Portsmouth)
3:00 PM - 4:20 PM
Wednesday, March 9, 2022
Thursday, March 10, 2022
Friday, March 11, 2022
Saturday, March 12, 2022
Sunday, March 13, 2022

Monday, April 11, 2022
Tuesday, April 12, 2022
3:00 PM Beyond the WIMP paradigm - Wei Xue (Florida U.)
Beyond the WIMP paradigm
- Wei Xue (Florida U.)
3:00 PM - 4:20 PM
Weakly-interacting massive particle (WIMP) has been the leading paradigm of dark matter for decades. Still, experimental searches for non-gravitational signatures of WIMPs have not found any positive evidence yet. It motivates us to think about new search strategies and novel dark matter models. My talk consists of the two directions looking beyond WIMP. First, I will introduce an effective field theory of superfluid helium. Developing the effective field theory is the first step of a project to build a dark matter direct detection detector using superfluid helium to search for sub-GeV mass dark matter. Then, in the other part of my talk, I will outline a new paradigm, where dark matter is made up of a novel form of matter, called “gapped continuum”, rather than an ordinary particle.
Wednesday, April 13, 2022
Thursday, April 14, 2022
Friday, April 15, 2022
Saturday, April 16, 2022
Sunday, April 17, 2022

Monday, April 25, 2022
Tuesday, April 26, 2022
3:00 PM Binary systems as gravitational wave detectors - Diego Blas (UAB-IFAE)
Binary systems as gravitational wave detectors
- Diego Blas (UAB-IFAE)
3:00 PM - 4:20 PM
The passage of gravitational waves (GWs) through a binary perturbs the trajectories of the two bodies, potentially causing observable changes to their orbital parameters. In the presence of a stochastic GW background (SGWB) these changes accumulate over time, causing the binary orbit to execute a random walk through parameter space. In this talk I will present a new formalism for calculating the full statistical evolution of a generic binary system in the presence of a SGWB, capturing all six of the binary's orbital parameters. I will show how this formalism can be applied to timing of binary pulsars and lunar laser ranging, thereby setting novel upper limits on the SGWB spectrum in a frequency band that is currently inaccessible to all other GW experiments.
Wednesday, April 27, 2022
Thursday, April 28, 2022
Friday, April 29, 2022
Saturday, April 30, 2022
Sunday, May 1, 2022

Monday, May 2, 2022
Tuesday, May 3, 2022
3:00 PM Cosmological tensions - Lavinia Heisenberg (Zurich, ETH and U. Heidelberg, ITP)
Cosmological tensions
- Lavinia Heisenberg (Zurich, ETH and U. Heidelberg, ITP)
3:00 PM - 4:20 PM
After introducing the standard model of cosmology and its parameters, I will discuss two important tensions between early and late-time measurements, namely the H0 tension and the sigma8 tension. Considering a small late-time deviation of the standard model, I will drive fully analytical conditions that any late-time dark energy model has to satisfy in order to solve both tensions simultaneously (see arxiv:2201.11623).
Wednesday, May 4, 2022
Thursday, May 5, 2022
Friday, May 6, 2022
Saturday, May 7, 2022
Sunday, May 8, 2022

Monday, May 30, 2022
Tuesday, May 31, 2022

4:00 PM