• Kyodo


Researchers unveiled Friday a giant telescope built underground in central Japan, joining an international race to detect the so-called gravitational waves emanating from space, the existence of which was predicted by Albert Einstein a century ago.

Takaaki Kajita, a University of Tokyo professor who shared this year’s Nobel Prize in physics, has led the project to build the “Kagra” telescope at the Kamioka mine site in Gifu Prefecture, which is also known as a major hub of neutrino research activities.

The university and other entities are expected to start a trial observation of gravitational waves, which are like ripples in space and time generated by the impact of gravity when an object moves, by next March. Full-scale activities using the telescope are scheduled to start in the fiscal year starting April 2017.

Spotting such waves means obtaining a new method to observe the universe, possibly offering an insight into phenomena such as the beginning of the universe and the birth of black holes.

Kagra is installed inside an L-shaped tunnel with each arm extending 3 kilometers and located more than 200 meters deep underground to minimize seismic noises, as signals from gravitational waves are very small, the researchers said.

The facility uses laser beams moving back and forth inside vacuum pipes that have mirrors placed at each end to detect the waves.

The construction of Kagra, which cost some ¥15 billion ($123 million), started in 2012 and the tunnel was completed in March 2014.

The researchers plan to enhance the sensitivity of the device by installing mirrors made from sapphire.

“Although the device is built, the project has just begun. We want to detect gravitational waves by improving levels of sensitivity to our target two years later,” Shinji Miyoki, associate professor of the University of Tokyo’s Institute for Cosmic Ray Research, said.

Countries are vying to detect the waves, with similar huge telescopes built in the United States and Europe.

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