How can we witness a galaxy’s death as it’s happening when the galaxy is 9 billion light years away?

Question

How can we witness a galaxy’s death as it’s happening when the galaxy is 9 billion light years away?

In: Physics

Answer 1

We can’t. We’re witnessing it 9 billion years later. It takes 9 billion year for the visual of that galaxy’s death to reach us. What you see when you see a galaxy dying is the image of what happened eons ago. Funnily enough, it mean that a dead galaxy still impact many other billion years after its death.