[ckissick]

The big bang was about 13.7 billion years ago. I suppose the star that they're talking about was 600 million years old, meaning it formed about 100 million years after the big bang. It took a long time before things cooled down enough to allow hydrogen to even form. This star formed early, and then exploded at a very young age. The larger the star, the shorter its lifespan.

As the universe expanded, this old star moved away from our region of space . When the Gamma Ray Burst occurred 13 billion years ago, the star was much closer to our region, and you'd think the light would have reached us billions of years ago. After all, the speed of light is constant, no matter what the relative velocities are of the object emitting the light, and the observer.

However, because the universe is expanding, it took longer for the light to get here because it has ever longer distances to travel as the universe continues to expand. It's like catching up to a speeding train. There is a threshold distance beyond which we cannot see into the past. We can't see back to the Big Bang because the light from it has not caught up to us yet, and it never will. The outermost regions of space are moving away from us at a rate greater than the speed of light.