# コーヒーミーティング過去ログ

2024-05-17

## Weather forecast and deep learning

大塚 成徳 (数理創造プログラム 研究員 / 理化学研究所 計算科学研究センター (R-CCS) データ同化研究チーム 研究員)

In this talk, I will introduce application of deep learning to weather forecasting. Recent years, tech companies, such as NVIDIA, Huawei, and Google, reported their deep learning-based global weather prediction models. These models were trained on so-called atmospheric reanalyses to emulate computationally demanding numerical weather prediction models. Although we still need physically-based models for various purposes, deep learning may change the future of weather predictions.

2024-05-10

## Forming black holes from stars

ルーシー・マクニール (数理創造プログラム 特別研究員)

Black holes which are the remnants of stars are being detected at a rate of a few per month using various optical telescopes and gravitational wave interferometers. They provide fruitful opportunity to test and challenge stellar evolution theory, which depends sensitively on our understanding of general relativity, quantum mechanics, particle physics and nuclear physics. In this coffee talk, I will present the physical concepts and mathematical scalings behind the formation of a black hole, after a star’s iron core collapses. I will quantify the key length, time and energy scales involved, and the (possibly surprising) importance of neutrino transport.

2024-04-26

## Exotica in Mathematics

佐野 岳人 (数理創造プログラム 基礎科学特別研究員)

Since the discovery of an exotic 7-dimensional sphere by J. Milnor in 1956, the study of exotic phenomena has become one of the central topics in topology. Here, an exotic sphere is a smooth manifold that is homeomorphic, but not diffeomorphic, to the standard sphere. In this talk, I will briefly explain the history of the discoveries of exotic phenomena and discuss some of the recent achievements related to knot theory.

2024-04-19

## A gentle introduction to fluid turbulence

カミリア・デミデム (数理創造プログラム 研究員)

Turbulence is everywhere around us, manifesting itself in seemingly trivial aspects of daily life, such as the act of pouring milk into coffee, while also shaping critical processes in fusion reactors, atmospheric dynamics and astrophysical phenomena. In this talk, I will try to review some fundamental aspects of turbulence and explain why it is so challenging to model it.

2024-04-12

## Singularity Theorems

長瀧 重博 (数理創造プログラム 副プログラムディレクター / 理化学研究所 開拓研究本部 (CPR) 長瀧天体ビッグバン研究室 主任研究員)

I am happy to introduce the Singularity Theorem, which was proved by Roger Penrose in 1965. He won the Nobel Prize in Physics in 2020 by the proof. I hope you will feel the outline of the proof and understand that the Singularity corresponds to a point outside of spacetime. If there is 1 minute left in my presentation, I would like to mention that Roger Penrose and Stephen Hawking proved the existence of (a) singularity(ies) in natural conditions at the beginning of our universe. Einstein's equation for general relativity is a kind of God's equation, but singularity theorems strongly suggest the limitation of general relativity. I want to thank Prof. Fujikawa, who requested that I give a presentation on the Singularity Theorems. His request motivated me to prepare for my presentation (originally, I was planning to give a short talk on stellar physics using a part of my notebook that I used in my lecture course at OIST).

2024-03-29

## Quantum channel characterization

松浦 俊司 (数理創造プログラム 客員研究員 / Senior Researcher, Hardware Inovation Lab, 1QBit, Canada)

The greatest challenge in building a quantum computer is noise. Suppressing noise in quantum systems is extremely difficult, which has led to a long-standing skepticism about the feasibility of quantum computers. So, what exactly is noise in the context of quantum computers? How is it characterized, and how is it measured? In this talk, we will discuss the nature of noise and, as specific examples of methods for characterizing it, we will talk about randomized benchmarking and tomography.

2024-03-22

## ORCID to auto-report your research contributions & manage your online visibility

カトゥリン・ボシゥメン (数理創造プログラム 副プログラムディレクター / Professor, Department of Physics, Toronto Metropolitan University, Canada)

We all have to report our papers (and grants) activities at least once per year to the institutions we work for. Different employers have different systems (e.g. RIKEN has RARS) and it is tiresome to fill these forms again and again. We also want to share or make this information visible to the wider scientific community, as part of looking for a new jobs or for new collaborators. Again a lot of different tools and databases exist (Scopus, Web of Science, Dimensions, Google Scholar, ResearchGate, Pubmed, etc.). In this talk I want to tell you about ORCID: what it is and what it can do for you. Especially, how it can help you solve the problems of reporting and widely disseminating your research accomplishments to the community across the different platforms, while managing it in just one place: your ORCID record. I'll demonstrate some of nice applications.

2024-03-15

## What is a Mathematical Model to Replicate Filtration Phenomena?

古川 賢 (数理創造プログラム 特別研究員 / 理化学研究所 開拓研究本部 (CPR) 三好予測科学研究室 特別研究員)

I will discuss a mathematical model concerning filtration of water and air. I will demonstrate how filtration phenomena can be mathematically replicated using special (less known) boundary conditions. I will also explain why these boundary conditions are necessary and discuss future possibilities.

2024-03-08

## Kin selection and social evolution

トーマス・ヒッチコック (数理創造プログラム 基礎科学特別研究員)

All of life is social, yet the evolution of social traits posed a problem to classical Darwinian thinking for over a century. I will introduce the concepts of kin selection, relatedness, and inclusive fitness and talk about how these resolved the puzzle of altruistic behaviours and revolutionised behavioural ecology in the process. I will then discuss how the scope of social evolution has expanded over the years to tackle a wider set of questions, including the origins of individuality itself.

2024-03-01

## Molecular evolution and the neutral theory

ジェフリ・フォーセット (数理創造プログラム 上級研究員)

Understanding how biological diversity is created is one of the most fundamental goals in biology. While the work of Charles Darwin formed the basic framework of Evolution, especially by highlighting the role of natural selection, it was the work of Motoo Kimura, who proposed the Neutral Theory and highlighted the role of stochastic processes, that formed the theoretical framework of molecular (i.e., DNA/RNA/protein) evolution. Here, I will explain the basic ideas of the Neutral Theory and the processes involved in creating the diversity at the molecular level.

2024-02-16

## Welcome to the new world, "Particle Zoo 2.0"

土井 琢身 (数理創造プログラム 専任研究員)

In 1960s, many new "fundamental" particles were found and called "Particle Zoo". Their systematic classification lead to the discovery of elementary particles, quarks. Since the beginning of 21c, however, a new kind of mysterious (exotic) particles are unexpectedly being discovered. In this talk, I will introduce this new world of "Particle Zoo 2.0" and its impact.

2024-02-09

## The undervalued and misunderstood importance of taxonomy in century 21th

ホセ サイード・グティエレス オルテガ (数理創造プログラム 基礎科学特別研究員)

Taxonomy, the branch of biology that classifies the living beings and give them scientific names, is not a hypothesis-driven science but a descriptive discipline that suffers of a great undervaluation in century 21th. Taxonomic papers will never be published in high impact journals, they won’t get many citations (if any), and getting funding for pure taxonomic research is basically impossible. Furthermore, taxonomy is often criticized for its apparent arbitrariness on how researchers decide to give name to a species, and attaching a scientific name to a group of organisms often seems trivial in a moment when in biology the definition of “species" is heavily discussed. Certainly, this is not a good moment for a biologist to specialize in taxonomy. (Un)fortunately, my research line somehow directed me to become a “part-time taxonomist”, which compels me to try to understand and overcome the challenges of this discipline. I will tell a few of my experiences as a taxonomist and will tell you about, in my opinion, the hottest topic in the modern history of taxonomy: should taxonomy be reinvented by updating its conventional rules?

2024-02-02

## Do Mathematicians Dream of Quantum Field Theory?

森脇 湧登 (数理創造プログラム 基礎科学特別研究員)

Leibniz discovered differentiation independently of "classical mechanics" and Riemann discovered Riemannian geometry independently of "theory of gravity". Let's ask: "Will Quantum field theory (a fundamental theory of physics) be reconstructed from pure mathematics?". Here I will talk about what I feel quantum field theory looks like as future mathematics based on my current understanding and expectations. One mathematician said that "quantum field theory is the mathematics of the 22nd century." So this is an extremely incomplete and informal talk, so please listen with an easy mind and a cup of coffee :)

2024-01-26

## What is a path integral?

クリスティ・コウジ・ケリー (数理創造プログラム 基礎科学特別研究員)

Path integrals are an important technical tool in physics for describing quantum systems. We will try to provide an intuitive account of why they appear in quantum theory and show why they are mathematically difficult to understand.

2024-01-19

## How were elements synthesized？

内藤 智也 (数理創造プログラム 基礎科学特別研究員)

I will explain how elements were synthesized in the Universe, which is a important topic in nuclear physics.

2024-01-05

## Brane Tiling: a bridge between geometry and gauge theory

金 東昱 (数理創造プログラム 特別研究員)

I will quickly overview the story of brane tiling, also known as dimer model, involving its relation with supersymmetric gauge theory and toric Calabi-Yau geometries.

2023-12-15

## Resurgence: making sense out of non-convergent series

本多 正純 (数理創造プログラム 上級研究員)

Interesting problems are often difficult to solve and this is why they are interesting. For such problems, we often aprroximate the answers by considering perturbation around solvable cases. Perturbative series obtained in such a way are often not convergent and their naive summation to all orders are divergent. In this talk, I will introduce techniques to make sense out of non-convergent perturbative series.

2023-12-08

## How can we use a quantum computer to study the ground state of the hydrogen molecule?

シュテッフェン・バッケス (数理創造プログラム 上級研究員 / 理化学研究所 創発物性科学研究センター (CEMS) 計算物質科学研究チーム 上級研究員)

Quantum computers differ fundamentally from classical computers, since their main computing unit, the "Qubit", is a quantum-mechanical object. But how can we actually exploit this "quantumness" to study or simulate a physical system? In this coffee talk I want to discuss the basic principles of Quantum computing and present just the smallest set of tools we need to obtain the ground state wave function and ground state energy of (a simplified model of) the hydrogen molecule.