Colloquium
48 events
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ColloquiumEmergence of Extreme Universe from Quantum Information
April 17 (Mon) at 16:00 - 17:30, 2023
Prof. Tadashi Takayanagi (Professor, Yukawa Institute for Theoretical Physics, Kyoto University)
Recently, a new interpretation of gravitational spacetime in terms of quantum entanglement has been obtained. The idea of holography in string theory provides a simple geometric computation of entanglement entropy. This generalizes the well-known Bekenstein-Hawking formula of black hole entropy and strongly suggests that a gravitational spacetime consists of many qubits with quantum entanglement. Also a new progress on black hole information problem has been made recently by applying this idea. I will explain these developments in this colloquium.
Venue: via Zoom
Event Official Language: English
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Colloquium
Scaling Optimal Transport for High dimensional Learning
January 24 (Tue) at 17:00 - 18:30, 2023
Dr. Gabriel Peyré (Research Director, CNRS/École Normale Supérieure, France)
iTHEMS-AIP Joint Colloquium Optimal transport (OT) has recently gained a lot of interest in machine learning. It is a natural tool to compare in a geometrically faithful way probability distributions. It finds applications in both supervised learning (using geometric loss functions) and unsupervised learning (to perform generative model fitting). OT is however plagued by the curse of dimensionality, since it might require a number of samples which grows exponentially with the dimension. In this talk, I will explain how to leverage entropic regularization methods to define computationally efficient loss functions, approximating OT with a better sample complexity. More information and references can be found on the website of our book "Computational Optimal Transport" (see related link below).
Venue: via Zoom
Event Official Language: English
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Colloquium
The Epidemiology and Economics of Physical Distancing during Infectious Disease Outbreaks
December 14 (Wed) at 11:00 - 12:30, 2022
Prof. Troy Day (Professor, Head of Department, Department of Mathematics and Statistics, Queen's University, Canada)
People's incentives during an infectious disease outbreak influence their behaviour, and this behaviour can impact how the outbreak unfolds. Early on during an outbreak, people are at little personal risk of infection and hence may be unwilling to change their lifestyle to slow the spread of disease. As the number of cases grows, however, people may then voluntarily take extreme measures to limit their exposure. Political leaders also respond to the welfare and changing desires of their constituents, through public health policies that themselves shape the course of the epidemic and its ultimate health and economic repercussions. In this talk I will use ideas from the study of differential games to model how individuals’ and politicians’ incentives change during an outbreak, and the epidemiological and economic consequences that ensue when these incentives are acted upon. Motivated by the COVID-19 pandemic, I focus on physical distancing behaviour and the imposition of stay-at-home orders by politicians. I show that there is a fundamental difference in the political, economic, and health consequences of an infectious disease outbreak depending on the degree of asymptomatic transmission. If transmission occurs primarily by asymptomatic carriers, then politicians will be incentivized to impose stay-at-home orders earlier and for longer than individuals would like. Despite such orders being unpopular, however, they ultimately benefit all individuals. On the other hand, if the disease is transmitted primarily by symptomatic infections, then individuals are incentivized to stay at home earlier and for longer than politicians would like. In this case, politicians will be incentivized to impose back-to-work orders that, despite being unpopular, will again ultimately be to the benefit of all individuals. This is joint work with David McAdams, Fuqua School of Business and Economics Department, Duke University.
Venue: via Zoom
Event Official Language: English
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Colloquium
From the Black Hole Conundrum to the Structure of Quantum Gravity
July 26 (Tue) at 15:30 - 17:00, 2022
Prof. Yasunori Nomura (Director, Berkeley Center for Theoretical Physics, University of California, Berkeley, USA)
Having a complete quantum theory of gravity has long been a major goal of theoretical physics. This is because a naive merger of quantum mechanics and general relativity — though it works in certain limited regimes — suffers from major theoretical problems. A particularly acute one arises when one considers the quantum mechanics of black holes: two fundamental principles of modern physics — the conservation of probability in quantum mechanics and the equivalence principle of general relativity — seem to be incompatible with each other. I will explain how recent theoretical progress begins to address this problem and portray the emerging picture of how spacetime and gravity behave at the level of full quantum gravity.
Venue: 2F Large Meeting Room, RIBF Building, RIKEN Wako Campus / via Zoom
Event Official Language: English
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Colloquium
The 20th MACS Colloquium
July 8 (Fri) at 15:00 - 18:00, 2022
Dr. Akira Mori (Associate Professor, Division of Biological Sciences, Graduate School of Science, Kyoto University)
Dr. Namiko Mitarai (Associate Professor, Niels Bohr Institute, University of Copenhagen, Denmark)15:00-16:00 Talk by Dr. Akira Mori "Defense with prey toxins: A snake that has both venomous and poisonous glands" 16:15-17:15 Talk by Dr. Namiko Mitarai "Who "sleeps" and when? Bacterial growth and dormancy" 17:15-18:00 Discussion
Venue: via Zoom
Event Official Language: Japanese
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Colloquium
How is turbulence born: Statistical mechanics and ecological collapse in transitional fluids
April 22 (Fri) at 15:00 - 16:30, 2022
Dr. Hong-Yan Shih (Assistant Research Fellow, Institute of Physics, Academia Sinica, Taiwan)
The onset of turbulence is ubiquitous in daily life and is important in various industrial applications, yet how fluids become turbulent has remained unsolved for more than a century. Recent experiments in pipe flow finally quantified this transition, showing that non-trivial statistics and spatiotemporal complexity develop as the flow velocity is increased. Combining numerical simulations of the hydrodynamics equations and an effective theory from statistical mechanics, we discovered the surprising fact that fluid behavior at the transition is governed by the emergent predator-prey dynamics, leading to the mathematical prediction that the laminar-turbulent transition is analogous to an ecosystem on the edge of extinction. This prediction demonstrates that the laminar-turbulent transition is a non-equilibrium phase transition in the directed percolation universality class, and provides a unified picture of transition to turbulence in various systems. I will also show our recent progresses on transitional turbulence, including how an extended ecological model with energy balance successfully recapitulates the spatiotemporal patterns beyond the critical point, and the determination of the critical behavior and an emergent novel phase under interactions in the experimental collaboration.
Venue: via Zoom
Event Official Language: English
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Colloquium
The 19th MACS Colloquium
April 18 (Mon) at 15:00 - 17:40, 2022
Dr. Yasuhiro Inoue (Professor, Department of Micro Engineering, Graduate School of Engineering, Kyoto University)
15:00- The 19th MACS Colloquium: Talk by Prof. Yasuhiro Inoue "Multicellular Dynamics Simulation of Morphogenesis" 16:05- MACS SG information session 17:10- Individual explanation by each study group (Zoom breakout room)
Venue: via Zoom
Event Official Language: Japanese
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Colloquium
The 18th MACS Colloquium
February 14 (Mon) at 15:00 - 17:30, 2022
Prof. Tetsuya Nagata (Professor, Division of Physics and Astronomy, Graduate School of Science, Kyoto University)
15:00- Talk by Prof. Tetsuya Nagata 16:05- 2021 MACS Result Briefing 16:30- Discussion
Venue: via Zoom
Event Official Language: Japanese
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Colloquium
The 17th MACS Colloquium
November 19 (Fri) at 15:00 - 18:00, 2021
Prof. Momoko Hayamizu (Assistant Professor, Faculty of Science and Engineering, School of Fundamental Science and Engineering, Waseda University / PRESTO Researcher, Japan Science and Technology Agency (JST))
Dr. Shigeru Kuratani (Chief Scientist, Evolutionary Morphology Laboratory, RIKEN Cluster for Pioneering Research (CPR) / Team Leader, Laboratory for Evolutionary Morphology, RIKEN Center for Biosystems Dynamics Research (BDR))15:00- Talk by Prof. Momoko Hayamizu 16:15- Talk by Dr. Shigeru Kuratani 17:15- Discussion
Venue: via Zoom
Event Official Language: Japanese
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Colloquium
High-Energy Neutrino Astrophysics in the Multimessenger Era
October 28 (Thu) at 15:00 - 16:30, 2021
Prof. Kohta Murase (Associate Professor, Pennsylvania State University, USA)
The discovery of high-energy cosmic neutrinos opened a new window of astroparticle physics. Their origin is a new mystery in the field, which is tightly connected to the long-standing puzzle about the origin of cosmic rays. I will give an overview of the latest results on high-energy neutrino and cosmic-ray observations, and demonstrate the power of "multimessenger" approaches. In particular, I will show that the observed fluxes of neutrinos, gamma rays, and extragalactic cosmic rays can be understood in a unified manner. I will also highlight the recent developments about astrophysical neutrino emission from supermassive black holes and violent transient phenomena. Possibilities of utilizing high-energy neutrinos as a probe of heavy dark matter may be discussed.
Venue: via Zoom
Event Official Language: English
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Colloquium
Finding Gravitational Waves from the Early Universe
September 27 (Mon) at 16:00 - 17:30, 2021
Prof. Eiichiro Komatsu (Director, Max Planck Institute for Astrophysics, Germany)
The Cosmic Microwave Background (CMB) gives a photographic image of the Universe when it was still an “infant”. We have been using it to test our ideas about the origin of the Universe. The CMB research told us a remarkable story: the structure we see in our Universe such as galaxies, stars, planets, and eventually ourselves originated from tiny quantum fluctuations in the period of the early Universe called cosmic inflation. While we have accumulated strong evidence for this picture, the extraordinary claim requires extraordinary evidence. The last prediction of inflation that is yet to be confirmed is the existence of primordial gravitational waves whose wavelength can be as big as billions of light years. To this end we have proposed to JAXA a new satellite mission called LiteBIRD, whose primary scientific goal is to find signatures of gravitational waves in the polarisation of the CMB. In this presentation we describe physics of gravitational waves from inflation, and the LiteBIRD proposal.
Venue: via Zoom
Event Official Language: English
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Colloquium
Quantitative Population Dynamics in Interdisciplinary Biology
July 8 (Thu) at 10:30 - 12:00, 2021
Prof. Shingo Iwami (Professor, Graduate School of Science, Nagoya University)
Through the course of life, from the moment of birth till death, an organism will achieve various states of equilibrium or ‘homeostasis’ which will inevitably encounter perturbations. The processes of cell growth, differentiation, infection, mutation, evolution and adaptation work together as a coordinated ‘system’, described by mathematical models for population dynamics, to maintain a healthy state. Any disruptions to this system leads to disease including infection, allergy, cancer, and aging. We are conducting interdisciplinary research to elucidate “Quantitative Population Dynamics” through the course of life with original mathematical theory and computational simulation, which are both our CORE approach. Our mathematical model-based approach has quantitatively improved a current gold-standard approach essentially relying on the statistical analysis of “snapshot data” during dynamic interaction processes in life sciences research. In this talk, I will explain how our interdisciplinary approach extends our understanding for complicated clinical data and apply real world problem with an example of the Novel Coronavirus Disease, COVID-19.
Venue: via Zoom
Event Official Language: English
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Colloquium
The 16th MACS Colloquium
July 5 (Mon) at 15:00 - 18:00, 2021
Prof. Yoshitaka Tanimura (Professor, Department of Chemistry, Graduate School of Science, Kyoto University)
Prof. Hidetoshi Nishimori (Senior Visiting Scientist, iTHEMS / Specially Appointed Professor, Tokyo Institute of Technology)15:00- Talk by Prof. Yoshitaka Tanimura 16:15- Talk by Prof. Hidetoshi Nishimori 17:15- Discussion
Venue: via Zoom
Event Official Language: Japanese
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Colloquium
The 15th MACS Colloquium
April 23 (Fri) at 15:00 - 17:30, 2021
Prof. Hiroshi Ishikawa (Professor, Faculty of Science and Engineering, Waseda University)
15:00- Talk by Prof. Hiroshi Ishikawa 16:05- MACS Student Conference FY2021
Venue: via Zoom
Event Official Language: Japanese
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Colloquium
Mirror symmetry and KAM theory
April 16 (Fri) at 13:30 - 15:00, 2021
Prof. Kenji Fukaya (Permanent Member, Simons Center for Geometry and Physics, Stony Brook University, New York, USA)
13:30pm-15:00pm (JST) Mirror symmetry is a phenomenon discovered in String theory and is much discussed recently in mathematics especially in the field of complex (algebraic) geometry and symplectic geometry. Strominger-Yau-Zaslow found that this phenomenon is closed related to a Lagrangian torus fibration. In an integrable system in Hamiltonian dynamics, the phase space is foliated by Lagrangian tori. I would like to explain a program that the Lagrangian torus fibration found by Strominger-Yau-Zaslow could be regarded as one appearing certain integrable system and KAM theory (which describes a amiltonian dynamics that is a perturbation of an integrable system) could appear in the situation of Mirror symmetry.
Venue: via Zoom
Event Official Language: English
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Colloquium
The 14th MACS Colloquium
February 17 (Wed) at 15:00 - 17:30, 2021
Prof. Yoshihiro Kaneko (Associate Professor, Division of Earth and Planetary Sciences, Graduate School of Science, Kyoto University)
15:00- Talk by Prof. Yoshihiro Kaneko 16:05- MACS Report Meeting FY2019 16:30- Discussion of each study group
Venue: via Zoom
Event Official Language: Japanese
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Colloquium
Geometry (形); Inconspicuous regulator that determines the fate of cells
December 14 (Mon) at 10:00 - 11:30, 2020
Prof. Sungrim Seirin-Lee (Professor, Hiroshima University)
December 14 at 10:00-11:30, 2020 (JST) December 13 at 20:00-21:30, 2020 (EST) In the history of mathematical study in pattern formation, the effect of domain has been considered as an important factor that can regulate spatial patterning. However, it is still unknown in biology how the geometry of the domain such as nuclear or cellular shapes can directly regulate the cell fate. In this talk, I will introduce two studies of spatial reorganization in chromatin and cellular dynamics and show that the domain is likely to play a critical role in determining the cell function.
Venue: via Zoom
Event Official Language: English
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Colloquium
The Unreasonable Effectiveness of Quantum Theory in Mathematics
November 26 (Thu) at 10:00 - 11:30, 2020
Prof. Robbert Dijkgraaf (Director, Institute for Advanced Study in Princeton, USA)
November 26 at 10:00-11:30, 2020 (JST) November 25 at 20:00-21:30, 2020 (EST) The physical concepts of quantum theory, in particular of quantum gravity and string theory, have proven to be extremely powerful in addressing deep problems in pure mathematics, from knot invariants to algebraic geometry. Is there such a thing as “quantum mathematics”? Should we add Feynman diagrams, strings, branes and black holes to the language of mathematics?
Venue: via Zoom
Event Official Language: English
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Colloquium
The 13th MACS Colloquium
November 13 (Fri) at 15:00 - 18:00, 2020
Prof. Shin-ya Kawaguchi (Professor, Division of Biological Sciences, Graduate School of Science, Kyoto University)
Dr. Yuji Sugita (Senior Research Scientist, iTHEMS / Chief Scientist, Theoretical Molecular Science Laboratory, RIKEN Cluster for Pioneering Research (CPR))15:00- Talk by Prof. Shin-ya Kawaguchi 16:15- Talk by Dr. Yuji Sugita 17:15- Discussion
Venue: via Zoom
Event Official Language: Japanese
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Colloquium
The 12th MACS Colloquium
July 17 (Fri) at 15:00 - 18:30, 2020
Prof. Yasuaki Hiraoka (Professor, Kyoto University Institute for Advanced Study (KUIAS) / Team Leader, Topological Data Analysis Team, RIKEN Center for Advanced Intelligence Project (AIP))
Prof. Motomu Tanaka15:00- Talk by Prof. Yasuaki Hiraoka 16:15- MACS Student Conference FY2020 17:30- Talk by Prof. Motomu Tanaka
Venue: via Zoom
Event Official Language: Japanese
48 events