Video: Head trip of the day

The observable universe spans 13.7 billion light years, with the background radiation aftershock of the Big Bang as the oldest, and farthest, signal. At that end of the universe lies the oldest material in creation, which, thanks to billions of years of expansion, has accelerated to almost the speed of light. That layer forms an event horizon past which not even light can travel, ringing our universe in what is essentially an inside out black hole.