Kyoto University students climb campus clock tower, clash with staff amid riot police presence



a group of people walking in front of a building: Students are seen on the roof of Kyoto University Clock Tower Centennial Hall on the university's Yoshida campus in Kyoto's Sakyo Ward, on Nov. 27, 2020, in this photo provide by a reader.


© The Mainichi
Students are seen on the roof of Kyoto University Clock Tower Centennial Hall on the university’s Yoshida campus in Kyoto’s Sakyo Ward, on Nov. 27, 2020, in this photo provide by a reader.

KYOTO — Riot police were deployed on a campus of the elite Kyoto University on Nov. 27 after students who had climbed a clock tower at the school clashed with staff.

Around noon that day, students set a ladder up on Clock Tower Centennial Hall on the university’s Yoshida campus in Kyoto’s Sakyo Ward, sparking a scuffle with staff who tried to stop them. Riot police were then summoned to the scene, entering the grounds through the front gate. The area was in an uproar for some time, but ultimately there were no injuries or arrests.

Students from the school’s Kumano-ryo dorm traditionally climb the clock tower during a festival at the residence. However, the university issued a notice on Nov. 25 declaring the custom “dangerous” and “an act of trespassing that infringes the Penal Code.” The university stated that it would “take stringent measures, including reporting infractions to police among other legal action” if the students tried to climb the tower.

During the standoff, the students hung banners from the clock tower and used a loudspeaker to slam the university’s refusal to negotiate. They also distributed flyers in the surrounding area.

Kyoto Prefectural Police told the Mainichi Shimbun, “A report was filed, and we entered the campus to prevent possible danger. We cannot reveal specifics about policing conditions.”

(Japanese original by Reiko Nakajima and Norikazu Chiba, Kyoto Bureau)

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Rotation of a molecule as an ‘internal clock’

Rotation of a molecule as an "internal clock"
Measured proton yield of the two molecular fragmentation processes ADT and EI (shaded blue and red) as a function of the pump-probe delay in comparison with the theoretical model calculation (blue and red line). Credit: MPI for Nuclear Physics

Using a new method, physicists at the Heidelberg Max Planck Institute for Nuclear Physics have investigated the ultrafast fragmentation of hydrogen molecules in intense laser fields in detail. They used the rotation of the molecule triggered by a laser pulse as an ‘internal clock’ to measure the timing of the reaction that takes place in a second laser pulse in two steps. Such a ‘rotational clock’ is a general concept applicable to sequential fragmentation processes in other molecules.


How does a molecule break apart in an intense laser field and what sequential processes take place how quickly? Physicists at the Heidelberg Max Planck Institute for Nuclear Physics have investigated this question in collaboration with a research group from Ottawa in Canada with a new method—studying the example of the hydrogen molecule H2. To do this, they use extremely short laser flashes on the order of femtoseconds (fs, a millionth of a billionth of a second). Such laser pulses also play a key role in controlling molecular reactions, as they directly influence the dynamics of the electrons responsible for chemical bonding.

If a hydrogen molecule (H2) is exposed to a strong infrared laser flash (800 nm wavelength) of a few 1014 W/cm2 intensity, the electric field of the laser first rips off one of the two electrons. More than 10 photons are absorbed at the same time in this ionization process. The remaining molecular ion H2+ with only one electron is no longer in equilibrium and becomes stretched due to the repulsion of the two protons. By absorbing further photons, it can break up into a proton (H+) and a neutral hydrogen atom (H). This reaction is called above threshold dissociation (ATD). If the molecular ion is stretched further to a nuclear distance of a few atomic radii, the remaining electron can absorb energy resonantly by the laser field, as in a small antenna, and is eventually also released. This mechanism is called enhanced ionization (EI). It leads to the ‘Coulomb explosion’ of the two repelling protons.

Processes distinguished via their kinetic energy

The researchers investigate these processes at the laser laboratory of the Max Planck Institute for Nuclear Physics using a reaction microscope, which allows for the detection of all charged fragments (protons, electrons) after the break-up of the molecule. The femtosecond laser pulses are focused onto a thin supersonic beam of hydrogen molecules in order to achieve the desired intensity. Protons from the ATD and EI processes can be distinguished via their kinetic energy.

Obviously, EI takes a little more time than ATD—but how much and can this be measured? Here, a problem arises since the laser pulse has to last long enough (approx. 25 fs) to start these processes,

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Building A Better Clock With Quantum Physics : Short Wave : NPR

Conceptual artwork of quantum entanglement, one of the consequences of quantum theory. Two particles will appear to be linked across space and time, with changes to one of the particles (such as an observation or measurement) affecting the other one.

Mark Garlick/Getty Images/Science Photo Libra


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Mark Garlick/Getty Images/Science Photo Libra

Conceptual artwork of quantum entanglement, one of the consequences of quantum theory. Two particles will appear to be linked across space and time, with changes to one of the particles (such as an observation or measurement) affecting the other one.

Mark Garlick/Getty Images/Science Photo Libra

Imagine building a better clock — with entangled atoms. Sound difficult? Not for Monika Schleier-Smith, associate professor of physics at Stanford University and 2020 MacArthur Fellow.

Schleier-Smith studies quantum mechanics, the theory that explains the nature of really small things: atoms, photons, and individual particles (e.g. electrons). Quantum mechanics is responsible for innovations in computers, telecommunications, and medicine. And those innovations often start in a lab.

Today on Short Wave, Schleier-Smith takes us into her laboratory — of lasers and mirrors — to break down what’s at work. We discuss her 2010 paper in the journal Physical Review Letters, in which she and her colleagues demonstrated the first atomic clock that harnessed the properties of quantum entanglement for greater precision.

Currently, the Schleier-Smith lab is venturing deeper into the quantum realm. They’re engineering systems to control interactions between particles that are long-ranged or non-local, which has implications for enabling new computational paradigms and building table-top simulations of quantum gravity.

To see all of this year’s MacArthur Fellows, click here.

This episode was produced by Brit Hanson, fact-checked by Ariela Zebede, and edited by Viet Le.

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