A Survey of Spacetime


Jolien Creighton — Geometry was invented to measure the Earth—to survey plots of land and to find distances between towns. We now use the same surveying methods to measure the distances to stars and the shape of the universe. But geometry is now understood to be the essence of space and time and the origin of gravity. Ripples in the geometry of spacetime produced by colliding black holes or by the big bang are now being sought with new types of observatories that are giving us our most precise survey of spacetime.