Report on Agora Keynote Sessions 2015

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  • Keynote Session 5
    <International Year of Light Special Session> The Universe, Time, Our Evolution and Future through “Light”

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Session Information

  • Date: 12:50-16:00 November 15th (Sun), 2015
  • Venue: International Conference Hall (3F), Tokyo International Exchange Center (TIEC)
  • Organizer:Japan Science and Technology Agency(JST)

Presenters

  • Yasuhiko Arakawa, Professor, The University of Tokyo & President, ICO
  • Tomonori Usuda, Professor, National Astronomical Observatory of Japan
  • Hidetoshi Katori, Professor, The University of Tokyo
  • Ryotaro Muramatsu, Artist & President, NAKED Inc
  • Kenichi Iga, Professor Emeritus, Former President, Tokyo Institute of Technology

Report

Evolution and Future through “Light”

2015 is the International Year of Light declared by the United Nations. In Agora Keynote Session 5, scholars who have been doing critical research on light and an artist using light were on stage, and they introduced the audience the world of light from various perspectives.

●Milestone year, reviewing the history of research on light

Miyoko Watanabe, Deputy Executive Director of JST, gave the opening words at the beginning of the session. She mentioned the following: Since the Great East Japan Earthquake, Japan began to realize that it is necessary to think about and create the future of science not solely by scientists but together with the general public. There will be a wide variety of presentations in this session, from scientific research to the role of light in the world of art and music.


  •   presenters
  • Welcome and Opening Remarks

The first presenter Yasuhiko Arakawa is a professor at the University of Tokyo and the ICO president who proposed the concept of quantum dot and its application to semiconductor lasers 33 years ago, contributing to the commercialization of quantum dot lasers. In his presentation titled “The Era of Light ~Towards the International Year of Light~”, he talked about the International Year of Light and the history of research on the light.


  •   presenters
  • Part1
    • Yasuhiko Arakawa, Professor, The University of Tokyo & President, ICO

The “International Year” is a period designated by the United Nations to advocate selected issues to groups and individuals worldwide to prioritize and come up with solutions, and 2015 was declared as the International Year of Light and Light-based Technologies. Prof. Arakawa explained that 2015 was declared the International Year of Light “because 2015 marks an important milestone when important research achievements on light were presented.”


First, Ibn al-Haitham, the Father of Modern Optics, wrote the “Kitab al-Manazir” (Book of Optics or Books of Visions) 1000 years ago which mentioned most of the basic ideas on optics such as the three laws of geometrical optics (direction, reflection, and refraction). Then, Augustin-Jean Fresnel, who invented the Fresnel lens, discovered that light was a transverse wave 200 years ago, followed by Albert Einstein, who proposed the general theory of relativity 100 years ago. In addition, the cosmic microwave background radiation as a sign of the Big Bang was discovered, and optical fibers were invested 50 years ago.


Prof. Arakawa also talked about the history of Nobel Prizes related to light and how laser technology has evolved in the last 57 years.


●Exploring the universe with higher-sensitivity telescope

Tomonori Usuda, a professor at the National Astronomical Observatory of Japan specializing in optics and infrared astronomy, spoke about exploring the universe with technology using “light” in his presentation “Light from the Universe ~ Subaru Telescope and the Extremely Large Telescope TMT”. He explained the importance of a cycle in which technological innovation leads to new discoveries and changes in how we see the universe, which then leads to the further need for technological innovation.


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  • Part2
    • Tomonori Usuda, Professor, National Astronomical Observatory of Japan

In recent years, telescopes have increased in size. The Subaru Telescope made in 1999 utilizes a single 8.2-meter mirror, but the TMT anticipated to be completed in 2024 will be equipped with a 30-meter segmented mirror. It will consist of 492 mirror segments at 1.44-meters each and harness 13-times more light-gathering power and 4-times more resolving power than the Subaru Telescope.


A 900 million-pixel digital camera called the Hyper Supreme-Cam (HSC) developed for the Subaru Telescope can capture not only the entire Andromeda galaxy, but it further enables individual stars to be resolved and examined. Furthermore, advancement in the Adaptive Optics (AO) technology to perform the real-time correction of atmospheric disturbances is anticipated to “allow ground-based telescopes to harness vision that exceeds those of the space telescopes.”


With all of these technologies squeezed into the TMT, it aims to see the initial creation of galaxy and stars in the universe from 12.9 billion years ago, which could not be clearly observed with the Subaru Telescope. Also through high precision spectroscopic technology, he hopes to “find traces of life by searching for planets as much similar to Earth as possible by detecting oxygen, water, organic matter, etc. in the atmosphere of Extrasolar planets.”


●Light that measures time with high precision

On the other hand, Professor Hidetoshi Katori of the University of Tokyo who invented the optical lattice clock spoke on the subject of “Measuring Space-Time with Light - Reading the 18th Place of Time in an Atomic Clock -.” Today, the International Atomic Time is realized by a cesium atomic clock. It becomes 1 second off in 30 million years, so it is a clock that is accurate to approximately 1 x 10^-15 or 15th place. In contrast, the optical lattice clocks gain or lose 1 second in twice the age of the universe which is 13.8 billion years, reading the 18th place. Prof. Katori explained that this clock may be used to redefine one second in the next 10 years.


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  • Part3
    • Hidetoshi Katori, Professor, The University of Tokyo

There are several reasons why we seek high-precision clocks. For example, it leads to the research of whether the physical constant is actually a constant. Currently, the interaction between dark matter and the atomic clock is not known, so there is a possibility that the time of an atomic clock changes when the Solar System passes through dark matter.


Also, Prof. Katori talked that “with a high-precision clock, the clock would become a quantum altimeter and may replace the benchmark in the future. A clock that reads time at the 18th decimal place would recognize that the time is passing by faster even if it were to be lifted up by a mere centimeter.


He explained “until now, the effects of general relativity were only recognized at the level of the universe. However, with the optical lattice clock, we have come to realize the deformation of the space time caused by gravity in our daily life.


●Visual art using the characteristics of light

The presentation “Manipulating Light” by artist Ryotaro Muramatsu, who is also the president of NAKED Inc. handling mainly digital images, began with a video of art using light. A famous example was the projection mapping at Tokyo Station, and he explained that the key in such art is to utilize the mechanism of “how human eyes recognize light.” We recognize light and “see”, but we are not conscious of the light source. An optical illusion is created by focusing on that gap.


For example, the company is working on a new way of expression through picture using a technique that the NTT research institute called “Deformation Lamps”, to show the illusion that still images appear to be moving. Only the brightness is changed, and the color is not touched, but “the image can be seen as if it is moving because people are sensitive to brightness.”


  •   presenters
  • Part4
    • Ryotaro Muramatsu, Artist &President, NAKED Inc

Moreover, the company handles art utilizing the characteristic of light like how it permeates and reflects. They are currently projecting the invention of a clear film that has the technology to permeate light from one angle and reflect it to another. By placing the film on the windows of an observatory, the scenery could be seen as usual during the day, but at night an image is projected and both the night view and the image could be seen.


Mr. Muramatsu said that he was attached to light as an artist. He said, “Without light it is pitch black, and there wouldn’t be the capability of expression to start with. Because there is light, there are colors, and we can feel that things are beautiful. And because there is recognition of colors, there are cultures around the world. Light is probably the most important thing to an artist.”


●Light is also a wave - live contrabass performance

The last presentation was by Kenichi Iga, Professor Emeritus, former president at Tokyo Institute of Technology and the inventor of a surface emitting laser, on the subject of “Light and Sound: the Beautiful World of Waves”. It was a harmonious presentation that included contrabass performance and playing music with a computer.


  •   presenters
  • Part5
    • Kenichi Iga, Professor Emeritus, Former President, Tokyo Institute of Technology

There was a moment where the vibration of a string was demonstrated by using a rubber band. It was visible that the vibration is a manner of transverse mode. He explained the mechanism of instrument: “Normally the string vibrating with transverse mode cannot radiate longitudinal sound wave to its normal direction. But a loud sound could be created by the longitudinal vibration in the board of instruments such as contrabass. That vibration is effectively driven by the string through the bridge. This is the physics of musical instruments.” He recommended the young participants to study the light and sound together as they both involve wave motions although they are currently studied separately.


There was a moment where the vibration of a string was demonstrated by using a rubber band. It was visible that the vibration is a manner of transverse mode. He explained the mechanism of instrument: “Normally the string vibrating with transverse mode cannot radiate longitudinal sound wave to its normal direction. But a loud sound could be created by the longitudinal vibration in the board of instruments such as contrabass. That vibration is effectively driven by the string through the bridge. This is the physics of musical instruments.” He recommended the young participants to study the light and sound together as they both involve wave motions although they are currently studied separately.


He also talked about the field of lasers, which he specializes in. With a semiconductor laser, when the electron and the hole enter the same space, they interfere and create light. In contrast to the LED with the same mechanism that spreads spontaneously emitted light, the laser becomes a beam with a pure spectrum because of the interference of reflecting mirrors.


Research on light became common after 1960. Prof. Iga said that the idea of surface emitting laser emerged while he was sleeping at night in 1977. He emphasized that “dissatisfaction was a mother of invention.” Amongst all the problems regarding lasers at the time, he was especially frustrated by the lack of semiconductor laser which could be made by the processes similar to that of integrated circuits. Later, the surface emitting laser developed by Prof. Iga was applied to things like laser mouse and laser printers.


There was time for questions and answers after every lecturer. The audience, ranging from high school students to specialists was very earnest on questioning the guests. The panelists answered with great passion that there was hardly any time left.


At the end of the session, Sotaro Ito, Deputy Executive Director of JST, gave the closing words and closed by commenting, “We heard many presentations about light by researchers and creators leading the world and representing Japan. I hope this inspired you to think about light.”


  •   presenters
  • Concluding Remarks

【Reporter's Comment】
After hearing all the interesting stories and research on light, three hours had gone by in an instance. There were many stories on light that truly intrigued me from the heart, including “The Hikari Exhibition” of the National Science Museum, not to mention the winning Nobel Prize of Mr. Takaaki Kajita. This session was deeply moving as I was able to actually feel and hear from the foremost figures of this topic. It was impressive to see that people from youth to elderly were studiously listening to the panelists. (Yu Yachi)

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