Reverse Engineering Space-Time
Albert Stebbins



A major aspect of modern observational cosmology is determining the geometry of space-time. Evidence for dark matter and "dark energy" are really statements about space-time geometry. Focusing on geometry circumvents questions of whether these phenomena are caused by exotic matter or modifications of gravity. It is shown how geometry can be simply expressed in terms of observable quantities, some of which are currently in use for cosmology, and some of which we can expect to use in coming decades. This analysis reveals glaring holes in our direct measurement of geometry and it is shown how these holes have been filled in by other assumptions about our universe.