The Tianlai project：radio detection of dark energy and the Square Kilometre Array

Dark energy makes up about three quarters of the total cosmic density，but its interaction with ordinary matter is very weak，hence its detection is indirect，i. e. through precise observation of the history of the cosmic expansion and the formation of its structure. To improve the accuracy and reliability of measurements，diverse ways of observation are necessary. At present，most dark energy observations are in the optical wavelength regime，while radio detection provides an alternative method with its own niche，although at present it has only just started. China has some basis in radio astronomy and related technology，and there are sites with a good electromagnetic observation environment，so it is possible for her to take the lead in this area. This article describes the Tianlai experiment，which should help China gain experience and develop the necessary technology to participate and play a role in the colossal international Square Kilometre Array radio telescope project.