vol. 114 | iTHES

Vol. 114, February 15th, 2016


  • Announcement
  • Upcoming Events
  • Paper of the week

Paper of the week


Observation of Gravitational Waves from a Binary Black Hole Merger

From the Office

The office of iTHES assistant, Ms.Chikako Oota is situated at the second floor of the main research building, room # 246. The extension number is 3261. She will be at the office from 10 a.m. to 16 p.m.


Gravitational wave detected finally!

As you may have already heard, the detection of an event of gravitational wave from colliding black holes was announced last week.Borrowing the words of our director Hatsuda, “This is a discovery once in a half millennium. We are extremely lucky to witness it."
Koutarou Kyutoku of ithes-phys team, who specializes in numerical relativity explains the significance of the discovery and physics behind it in this issue's paper of the week.
Also Franco Nori shared with us a personal message from Fabio Marchesoni, who visited us a couple of times in the past, including the visit a year ago.Prof. Marchesoni is one of the founding members of Virgo, which is another gravitational wave detector, and wrote up a plain and concise explanation of the event, which you can read here .

The iTHES Researcher, Masato Taki, received the Best Poster Award at the poster session of the homecoming day (Jan.25, 2016) for the former Special Postdoctoral Researchers (SPDR). He was a SPDR at Hashimoto's mathematical physics lab. and gave a presentation on "Research on duality of field and string theory via topological string theory".
Congratulations, Masato!

Upcoming Events

Date and Time: 10:30-12:00, Feb. 16 (Tuesday), 2016
Place: S406 Bioscience Building, RIKEN Wako Campus
(Bioscience Building is “S01” in the map)

Speaker: Prof. Catherine Beauchemin (Department of Physics, Ryerson University)
Title: An introduction to the field of virophysics

Experimentation in vitro and in vivo has traditionally been the only way to study virus infections; there is no such thing as theoretical virology. When adopting an experiment-only approach, one must rely on common-sense assumptions to derive knowledge (e.g., a higher viral count means a fitter virus). These assumptions often go untested due to difficulties in controlling individual components of infection without affecting others. In this talk, I will show how mathematical and computer models (MCMs) allow us to better understand cell-virus interactions, and to probe the reproducibility of virology results which is an important problem in health research. I will introduce our MCM for influenza infection in vitro and illustrate its use to determine the effect of a specific mutation (genotype) on every aspect of the virus' replication fitness (phenotype). I will demonstrate the MCMs' ability to find flaws in experiments, and determine antiviral efficacy and optimal combination therapy.

This talk is suitable for mathematicians, physicists, and virologists alike.

Date: Feb 19 (Fri)
Time: 14:00-
Place: Large conference room at the 2nd floor in main cafeteria

Speaker: Dr. Chao GAO (Renming University of China)
Title: Universal three-body physics and the link to many-body physics

Abstract: I will introduce to you the exotic universal three-body physics, the Efimov states, that is, three-body bound states with scaling spectrum emerging at two-body resonances. I will then discuss the link between few-body and many-body physics through virial expansion. Specifically I will take the example of unitary Fermi gases, where we shall see the role of the so-called three-body parameter. I will also introduce to you another kind of universal three-body bound states, the super-Efimov states, which is more peculiar and firstly discovered in two-dimensional systems at p-wave channel. I will discuss its origin at fundamental quantum mechanics level.

The 8th iTHES Academic-Industrial Innovation Lecture
Date: March 1st (Tue.)
Place: Nishina Hall, Wako, RIKEN
Company: JSOL

12th International Conference on Low Energy Antiproton Physics (LEAP2016)
Date: March 6-11, 2016
Place: Kanazawa Japan

The intent of LEAP 2016 is to actively stimulate the overlap and dialogue between various research forefronts in the diversified field of antiproton physics and related field involving meson and baryon with strangeness.
iTHES is a cosponsor of this meeting.
Feel free to join !

iTHES Symposium
Baymfest in Tokyo:
"Exploring Extreme Forms of Matter - A symposium in honor of Professor Gordon Baym -"
Date: March 14 (Mon) 2016. 10:00am-
Place: Faculty of Science 4th-bldg 1320, Department of Physics, The University of Tokyo

This is a joint symposium hosted by The University of Tokyo and RIKEN on nuclear physics, condensed matter physics and astrophysics in hornor of Prof. Gordon Baym's 80th birth year. We welcome participation of all scientists who are interested in these fields and related interdisciplinary research. We hope to have fruitful discussions on the current status and future perspectives in these fields at the symposium.

Person of the Week

On Feb 11, the Laser Interferometric Gravitational-Wave Observatory (LIGO) announced the first direct detection of gravitational waves from a binary-black-hole merger. Gravitational waves are the propagation of gravitation with the speed of light (like electromagnetic waves in electromagnetism), which are sometimes referred to as "the spacetime ripples," and are predicted as a part of general relativity by Einstein 100 years ago. Strong gravitational radiation is generated when massive objects move with the large velocity comparable to the speed of light. The leading source candidate is the merger of binary black holes or binary neutron stars. Previous observations of binary pulsars (neutron stars) have already shown that gravitational waves are emitted by the rate consistent with general relativity, but we had never observed gravitational waves directly. Thus, the direct detection of gravitational waves was a key to confirm general relativity. The LIGO consists of two detectors located at Livingston and Hanford in US, and is designed to measure a tiny change of the length (or light-travel time) in two orthogonal directions caused by gravitational waves. On 2015 Sep 14, these two detectors succeeded in detecting the variation of the length by a factor of 10^(-21) - 1 in 1,000,000,000,000,000,000,000 - that amounts to the variation by a hydrogen atom (or Bohr radius) between the sun and earth. The signal, named GW 150914 following the convention of gamma-ray bursts, turned out to be consistent with gravitational waves from the merger of 29 and 36 solar mass black holes predicted in general relativity. This confirms the existence of gravitational waves and black holes directly, and therefore general relativity now seems to work perfectly even in the strong-field regime. The masses of the black holes, ~30 solar mass, are larger by a factor of a few than what astronomers usually expect. The study of the origin of these black holes will promote our understanding of the stellar formation, evolution, and death. In the coming few years, the LIGO will be upgraded, and more stringent test of general relativity will be conducted. Furthermore, Europian Virgo and Japanese KAGRA will start observations and the sky localization of gravitational-wave sources becomes much more accurate. This will open the way to multi-messenger astronomy, where an astronomical event is observed by electromagnetic waves, neutrinos, and gravitational waves.
Koutarou Kyutoku, iTHES-phys team