大样本恒星演化与特殊恒星的形成 | 本周物理学术讲座

1大样本恒星演化与特殊恒星的形成

报告人：韩占文，云南天文台

时间：9月8日（周四）14:00

单位：清华大学物理系

地点：蒙民伟科技大楼南楼S727

“恒星结构和演化理论”是天体物理的两大理论体系之一。从上个世纪末开始，大样本的天体观测成为一种新的观测模式，一些特殊恒星（如Ia型超新星）也成为天体物理发展的基石，大样本恒星演化方法应运而生。本报告将首先介绍大样本恒星演化方法，即研究恒星“群体”演化的方法（同时也介绍恒星演化和双星演化）；然后用热亚矮星、Ia型超新星、双白矮星等特殊恒星作为例子，介绍如何用大样本恒星演化方法建立特殊恒星形成模型，同时介绍大样本恒星演化在引力波探测方面的应用；最后介绍如何将特殊恒星形成模型用于星系中的星族研究。

2Recent stop searches at the LHC

报告人：韩成成，东京大学

时间： 9月6日（周二）16:00

单位：中科院理论物理研究所

地点：新楼6420报告厅

Will briefly review the recent stop searches at the LHC and pay special attention to the 3-sigma excess in a signal region. 

3Wheeler's Inventive Mind 

报告人：黄卓然，Oak Ridge National Laboratory

时间： 9月7日（周三）15:00

单位：中科院理论物理研究所

地点：新楼6420报告厅

John A. Wheeler's inventive mind covered vast areas, from nuclear physics, single-electron universe, wormholes, blackholes, quantum delayed-choice experiment, and many others. We will review the history of Wheeler's notable ideas and trace how they eventually led him from the pictures of "everything is particles" and "everything is fields" to the acceptance of the concepts of blackholes. He then proceeded to tackle the difficult question on the existence of the Universe. We will review how he combined his knowledge of blackholes and quantum mechanics to reach his new picture of the Universe as "It from Bit".

4Evolution of Stubbornness

报告人：Shun Kurokawa，Institute of Zoology

时间： 9月8日（周四）10:30

单位：中科院理论物理研究所

地点：新楼6420报告厅

The existence of cooperation demands explanation since cooperation is costly to the actor while cooperation is beneficial to the receiver. In repeated interactions, when players adopt the strategy "If you cooperate, then I cooperate. If you defect, then I defect.", the evolution of cooperation is possible. And this is a major mechanism which is called direct reciprocity. Direct reciprocity is based on the assumption that players can use the information about the opponent's behavior; however, the information about the opponent's behavior is sometimes imperfect. And it is not obvious what behavior is most likely to evolve in the case wherein information about the opponent is absent.

Here, I consider the game in which there are two strategies; one is conditional cooperators and the other is unconditional defectors in a repeated prisoner's dilemma. And by analyzing evolutionarily stable strategy (ESS) analysis, I have revealed that the strategy with stubbornness which behaves "If I cooperate in the last move, then I cooperate also in the next round. If I defect in the last move, then I defect also in the next round." in the case wherein information about the opponent's behavior is absent, has the loosest ESS condition. This indicates that the evolution of stubbornness is favored by natural selection. I also would like to discuss the relationship between this study and studies on win-stay, lose-shift.

5Effective Description of Black Holes via Hydrodynamics  

报告人：张云龙，APCTP, South Korea

时间：9月8日（周四）14:00

单位：中科院理论物理研究所

地点：新楼6420报告厅

In this talk, I will summarize the progress on effective descriptions of the black hole via hydrodynamics,especially on the approach through membrane paradigm and Rindler fluid dynamics, as well as the near horizon properties of black hole in the viewpoint of a dual fluid.

6Black hole instabilities and the formation of singularities in general relativity

报告人：Pau Figueras，Queen Mary University of London

时间： 9月8日（周四）16:00

单位：北京师范大学物理学系

地点：物理楼106

Black holes play a central role in our understanding of general relativity, the currently accepted classical theory of gravity. The recent discovery of gravitational waves by the Ligo-Virgo collaboration confirmed their existence in Nature. But the importance of four dimensional black holes to describe some of the observed compact dark objects in the Universe hinges on their dynamical stability under small perturbations. In recent years, motivated by more fundamental theories of gravity such as string theory, there has been a lot of interest in the community to study black holes in spacetimes with more than four spacetime dimensions. In this talk I will show that in dimensions higher than four, black holes can be dynamically unstable. Furthermore, I will present results of numerical simulations of these instabilities in full non-linear regime that suggest that unstable horizons develop a fractal structure that leads to a naked singularity in finite time. Moreover, I will argue that the mechanism behind these instabilities is universal. These results provide evidence that the weak cosmic censorship conjecture, which is the greatest unsolved problem in general relativity, is false in spacetimes with more than four dimensions.

7Testing Foundations of Modern Cosmology 

报告人：Pengjie Zhang，Shanghai Jiao Tong University

时间： 9月8日（周四）16:00

单位：清华大学物理系

地点：蒙民伟科技大楼南楼S727

The establishment of the standard cosmology is not only a great success, but also a greater challenge. It has already revealed the existence of elusive dark matter and dark energy. But it may also imply the existence of deeper unknown unknowns. It is time to scrutinize key ingredients of cosmology, some of them are century old, with state of the art observations and analysis. I will report some recent progresses in these retrospective researches.

8The first nonsymmorphic topological insulator: prediction and discovery

报告人：Aris Alexandradinata，Yale University

时间：9月9日（周五）10:30

单位：中科院理论物理研究所

地点：M楼830

Spatial symmetries in crystals are distinguished by whether they preserve the spatial origin. I will show how this basic geometric property gives rise to a new topology in band insulators, which we propose (and subsequently discover) to lie in the large-gap insulators: KHgX (X=As,Sb,Bi). These insulators are described by generalized symmetries that combine space-time transformations with quasimomentum translations in the Brillouin torus. This provides a natural generalization of space groups, such that real and quasimomentum spaces are placed on equal footing. A broader consequence of our theory is a connection between band topology and group cohomology.

更多报告信息：中国物理学会期刊网学术讲座列表

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