Module 9 · Einstein's gravity
From 1915 to 2022
General relativity, tested
Five milestones, with the date each source gives.
1915
General relativity
Einstein's theory explains the 43 arcseconds per century that Mercury's orbit advances beyond Newton.
1919
The eclipse expedition
Eddington's team measures starlight bent by the Sun.
Today
GPS clocks
The satellite clocks need a net correction of about 38 microseconds a day, from gravity and speed combined.
14 Sep 2015
LIGO hears gravitational waves
Two black holes merged about 1.3 billion light-years away; announced on 11 February 2016.
12 May 2022
A picture of Sagittarius A*
The Event Horizon Telescope image of the black hole at the centre of the Milky Way, about four million solar masses.