Chinese contribute to detection of gravitational wave -- Tsinghua professor

BEIJING -- The triumph of directly detecting a gravitational wave has made it possible for human beings to look deeper into space when the US-based Laser Interferometer Gravitational-Wave Observatory (LIGO) successfully sensed the ripples in the fabric of spacetime caused by the merger of two massive black holes 1.3 billion years ago.

This discovery is due to the efforts of over 1,000 scientists from universities around the United States as well as in 14 other countries. Among them was a team of five Chinese scientists from Tsinghua University who worked on gravitational wave data analysis.

"It is an extremely exciting discovery, and our group dealt with data," said Prof. Cao Junwei, head of LIGO Scientific Collaboration research group at Tsinghua University. As the only member from mainland China in LIGO scientific collaboration (LSC), Cao's group focused on gravitational wave data analysis using advanced computing technologies to help "purify" the received signals.

In search for real gravitational wave signals, scientists had to damp out irrelevant vibrations caused by noise sources, which is no easier than identifying a Morse code tapped on a wine glass at a grand party bustling with noise.

The group applied a method of "machine learning" to the analysis, which originated in the field of artificial intelligence. It compared the signals in the gravitational wave channel with other channels, and the coupling of signals helped rule out irrelevant signals. That transformed the signal detection and identification into problems of data analysis and processing, which is a strong point of the Tsinghua group, Cao told Xinhua.

"In a long period of time, LIGO was not sensitive enough to see a passing gravitational wave. What we captured and processed are all noises. But it was no waste of time. The experiences helped LIGO upgrade and improve sensitivity," Cao said.

He noted that the observation of a gravitational wave fulfilled the prediction of Einstein's general theory of relativity and opened a new window on exploring space.

It will also drive cutting-edge development of optics, engineering, computer science and many other relevant subjects, he said.

To accelerate its domestic research, Cao said, China should develop its own gravitational wave observatory, but before that, loads of work needs to be done.