A friend told me that if a galaxy is 13 billion light years away, it means the universise is at least 13 billion years old. I don't get it? So, light years does measure time? Or is it because this new "galaxy" found is the oldest galaxy in existence? He explained it to me that it took the image of that galaxy 13 billion years to get to our eyes, that's how we know our Universe is at least 13 billion years old. ?