China launched a project to explore the primordial gravitational waves in Ali, Tibet on December 13. The Ali project, which aims at measuring the polarization patterns of the cosmic microwave background radiation in the northern sky, was put forward in 2014 under the leadership of Prof. Zhang Xinmin’s group at the Institute of High Energy Physics and has become very promising in exploring primordial gravitational waves, which is very complementary to the US Background Imaging of Cosmic Extragalactic Polarization program (BICEP) experiment at the south pole.

Earlier this year, researchers from the Laser Interferometer Gravitational-Wave Observatory (LIGO) reported the detection of gravitational waves. This breakthrough was expected to initiate a novel probe of cosmology, the nature of gravity as well as fundamental physics.

Prof. Zhang Xinmin, the chief scientist of the project said the Ali project could start the scientific observation in the next five years after its construction, and lead China’s research on primordial gravitational waves to the international frontier.

Zhang continued to explain that primordial gravitational waves were produced from quantum fluctuations of our universe at the very early moment right after the big bang. Both inflation and non-singular models predict the existence of primordial gravitational waves. By detecting and measuring them in the CMB polarization experiments, we have chance to probe the origin of the universe.

The Ali project will have access to northern hemisphere, larger angular scales and larger sky. Therefore it is expected yield better dust statistics, identification of low dust region for deep searches. What’s more, if there is a primordial signal, it will also enhance significance to discovery level or reduce sample variance.

“After about three years’ discussion, the Ali project has developed current, middle-term and long-term road map.” introduced Prof. Wang Yifang, IHEP Director on the launching ceremony of the Ali project, “we can also benefit from this project to develop cryogenic superconducting detection technologies in China.”

IHEP plays a leading role in the project and will carry out the project with the participation from domestic and international institute and universities. It will provide a wide range of training in experimental and theoretical physics and technology.

Prof. Chao-lin Kuo, the senior consultant of the Ali project commented that Ali-CMB was a well-timed, well-planned CMB initiative that would deliver cutting edge results, increase visibility of science in China and help participants develop a unique perspective of the planet Earth.

He added that, together with BICEP and two new telescopes in Chile’s Atacama Desert, the Ali project will become three bases to detect the primordial gravitational waves in north and south.

Construction Starts in Ali, Tibet (Image by IHEP)

Road Construction for Ali-CMB Project (Image by IHEP)