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If we can see billions of light years into space how do we know we're not looking at our galaxy in the past?

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    $\begingroup$ We know we do. Not billions of light years, since the Milky Way is not that large, but up to a few ten thousands of light years. $\endgroup$ – pfnuesel Mar 2 '16 at 14:21
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    $\begingroup$ I have a feeling the OP means: can we see our galaxy forming 13 billions years ago? Which would be theoretically possible if the universe is closed... $\endgroup$ – lemon Mar 2 '16 at 14:33