surface hole
131Sinkhole — For the War of 1812 battle, see Battle of the Sink Hole. For the type of wallet, see Wallet band#Swallet. A sink hole in Oman …
132Introduction to general relativity — General relativity (GR) is a theory of gravitation that was developed by Albert Einstein between 1907 and 1915. According to general relativity, the observed gravitational attraction between masses results from the warping of space and time by… …
