At the Edge of Time: Exploring the Mysteries of Our Universe’s First Seconds (Science Essentials Book 32)

by Dan Hooper

In effect, the expansion of our universe causes all points in space to be surrounded by an impenetrable horizon, beyond which nothing can be observed and no communications can reach. In the current epoch, our cosmic horizon is the surface of a sphere with a radius of about 46.5 billion light years, with us at the center.1 This sphere is, for all practical purposes, our universe. Its volume contains all of the space that we can see, study, witness, experience, communicate with, influence, or be influenced by. The boundary of this sphere is entirely impenetrable and forever will be—at least as long as the expansion rate of our universe doesn’t begin to slow down. Things beyond this distance are not merely obscured from our vision, but are utterly disconnected from us. All of space beyond this distance is forever lost from our world.