system
Given the following post, respond as if you're commenting on Reddit:
human
If gravity causes time dilation, wouldn't deep gravity wells create their own red-shift? How do astronomers distinguish close massive objects from distant objects?
gpt
They estimate the depth of the gravity well. We sit in one ourselves so this can be taken into account as well. It doesn’t matter much. At distances where this is a large effect the random motion of galaxies is still important. At distances where you get nice measurements the redshift is so large the gravity wells don’t have a large impact any more.