China Team Finds First Evidence of Speed of Gravity
By wchung | 18 Jun, 2026

Scientists in China published data Wednesday comprising the first evidence to support the hypothesis that the force of gravity doesn’t act instantaneously but propagates at the speed of light.

Longstanding efforts to measure the speed of gravity through experiments and observations have all ended in failure until the Chinese team noted that the Newtonian Earth tide formula includes a delay factor caused by the propagation of gravity.

Six observations of total and annular solar eclipses, as well as Earth tides, was made by a team headed by Tang Keyun, a researcher with the Institute of Geology and Geophysics of the Chinese Academy of Sciences (CAS). Earth tides are the less-than-one meter deformations of the earth’s surface caused by the gravitational tug of the moon, and to a lesser extent, the sun.

With the help of the China Earthquake Administration and the University of the CAS, the team studied its data and found that the gravitational force released from the sun and the gravitational force recorded at ground stations on Earth did not travel at the same speed. The time difference corresponded precisely with the time it takes for light to travel from the sun to observation stations on Earth.

Noting that the observation stations are located near oceans, and considering the possibility that the influence of ocean tides might have been strong enough to influence the results, the team conducted separate observations of Earth tides from two stations in Tibet and Xinjiang, both of which are far from all four oceans. They also took other measures to filter out other potential disturbances.

Applying the new data to the propagation equation of gravity, Tang’s team calculated the speed of gravity to be about 0.93 to 1.05 times the speed of light with a margin of error of about 5%. This is the first study to provide compelling evidence that gravity travels at the speed of light.

The team’s findings were published online in English by the German science and technology publishing group Springer. Printed articles in both Chinese and English will be published in a January 2013 edition of the Chinese Science Bulletin, according to the CAS Institute of Geology and Geophysics.