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A new Ear towards the Universe

published by Karen Esser
Dr. Kenta Kiuchi MPI AEI © Standortmanagement Golm GmbH

Since 2019 Dr. Kenta Kiuchi has been a group leader in the Numerical and Relativistic Astrophysics department at the Max Planck Institute for Gravitational Physics (Albert Einstein Institute) in the Potsdam Science Park. Using complex simulations, he helps other researchers to detect gravitational waves of colliding neutron stars – and thus listen to the universe with ‘new ears’.

When asked what motivated him to research gravitational waves, Dr. Kenta Kiuchi answers with an anecdote from his student days. At the time, he says, he came across a book on the subject: “At that time, the direct observation of gravitational waves, that is, waves in space-time triggered by moving masses, was still a dream” he emphasises: “Einstein had already predicted them in 1916 with his general theory of relativity, but they had not yet been proven. The book compared their proof to the development of a new sensory organ. One could then listen to the universe with ‘new ears’. This image stayed with me to this day.”

Curvatures in spacetime

In 2015, gravitational waves were experimentally detected by researchers at the Laser Interferometer Gravitational-Wave Observatory (LIGO for short). Since then, they have received mainstream attention. Nevertheless, only few people truly grasp what they are. In order to understand gravitational waves, non-physicists often have to use metaphors. Dr. Kiuchi, who works as a group leader in the Department of Numerical and Relativistic Astrophysics at the Max Planck Institute for Gravitational Physics (Albert Einstein Institute) in the Potsdam Science Park, dares an explanation: “According to Einstein, the space-time continuum is elastic. It is deformed by every object in it, humans as well as planets.” This can be thought of as something like a billiard ball placed on a sheet stretched between posts and pressing it in with its mass, says Kenta Kiuchi: “These deformations, or better curvatures, in space-time are what we call gravity.” Thus, when objects move through space, they cause compression and stretching of space. “Gravitational waves, in that sense, are a bit akin to waves in water,” is how he describes it.

And precisely because gravitational waves affect space-time itself, Kiuchi says, they are so difficult to detect: “Gravitational waves can’t be easily measured in space, because they are extremely weak signal.” What does work, however, is sending light through space. If sufficiently strong gravitational waves travelled through its path, this would lengthen or shorten the distance the light has to travel. This difference can be measured, and gravitational waves can be detected. This is precisely what the LIGO team proved successfully in their 3 km long detectors.

From space to earth. From research to application.

Exciting times for Mr. Kiuchi. At the Albert Einstein Institute, he simulates neutron star collisions, an important source of gravitational waves. “The radius of neutron stars is relatively small, only about ten kilometers, but their mass is equivalent to that of a sun”, he explains: “When two such compact objects collide, gravitational waves are inevitable.” Because these collisions happen far from earth, in space, the signals from these waves are relatively weak once they reach us and are “hidden in the noise of the data”, as Dr. Kiuchi puts it. That’s why simulations are needed. To detect gravitational waves, scientists identify their source and filter out information such as mass and distance from the measured data. For this, they need “templates” of the waves, known as gravitational waveforms. Dr. Kiuchi and his team create models of known collisions to predict such waveforms.

Kenta Kiuchi’s work is typical basic research. With it, he feels in good hands at the Potsdam Science Park, where research and practice should also come together. In order to make a contribution, to Kiuchi, it sometimes less important to be involved in the development of a concrete solution or product. The important thing, he says, is to produce findings that others can build upon – and perhaps use to create something new later on. Here, too, he can point to the man who gave his institute its name, Albert Einstein: “When Einstein worked on his general theory of relativity, he certainly did so out of pure scientific curiosity,” says Dr. Kiuchi: “I’m very confident that he didn’t think that, on the basis of it, we would one day be able to develop GPS devices to deal with our navigation in road traffic. Nevertheless, that’s exactly what happened. Without his historical insights, the invention of this technology would not have been possible.”

A dynamic metropolitan region with space for research

The move from Japan to Germany was not difficult for him and his family, he explains. The Berlin-Brandenburg metropolitan region has a lot to offer to international researchers and their families, for whom work often determines where they live. In this sense, he says, his wife, who works as a foreign correspondent for a major Japanese media outlet, also benefits indirectly in her career from the favorable location of the Potsdam Science Park in the capital region.

For Kenta Kiuchi himself, it is mainly the science-oriented atmosphere at the Max Planck Institute that contributes much to the quality of his work. “At a Japanese university, I would have to devote a lot of time to teaching. That is an important and honorable task. But in my field, the focus on research is essential,” he says: “Here, I have the freedom to do just that. I appreciate that.” Thus, Kenta Kiuchi and his team will continue to keep an open ear towards the universe.

This blog and the projects of Standortmanagement Golm GmbH in the Potsdam Science Park are funded by the European Regional Development Fund (ERDF) and the state of Brandenburg.

Image Credits: Dr. Kenta Kiuchi (Max Planck Institute for Gravitational Physics) © Standortmanagement Golm GmbH, Karen Esser