A Cosmological Constant Is the Most Important Force on Large Scales

In cos logy, we want to know what the universe as a whole is doing. The most important force, force, on large scales, on sort of cosmological scales, is gravity. We start by guessing at what the universe is made of. How much of it is there? There is evidence from our observation of the universe that there is a form of matter which is not ordinary matter and sends light towards us. This leads into general relativity - einstein's idea about howa gravity works.