This amazing scientific achievement was announced today, verifying Einsteins theory of relativity. We know gravity as the pull of the Earth; a steady dependable pull causing things to fall. There are events happening is space such as two black holes spinning into one another becoming one. The gravity field (pull) around this kind of event varies greatly with time. These variations are propagating away as a gravitational waves distorting the fabric of space. These waves can be detected with extremely sensitive instruments as now has been done. Here is a paragraph quoted from the announcement.