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It is known that spacetime is curved,so I am wandering to know if its possible to look into space and we see earth (light from earth long long ago). Did I understood spacetime correctly and if its possible then can some one after million years can see dinosaurs by looking into space?

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migrated from space.stackexchange.com Jul 20 '15 at 17:43

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    $\begingroup$ astronomy.stackexchange.com/q/11017/1980 - This question seems very similar. $\endgroup$ – duzzy Jul 20 '15 at 19:25
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    $\begingroup$ @duzzy: That question is about looking at a place in the Milky Way where Earth was previously, whereas the present one is about looking across the entire Universe. Probably there are others like this, but I can say briefly that no, it is not possible. It would require a so-called "closed Universe" which observations indicate we don't live in, and even if we did, the Universe would collapse exactly at the time that the light from Earth had traversed the Universe and reached us (on top of this there are of course issues with telescopes not even being able to se planets a few lightyears away…). $\endgroup$ – pela Jul 21 '15 at 10:21
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The answer, for the universe we live in, is almost certainly No. The best guess is that the universe, on the largest scale, is very nearly flat and probably extends infinitely in all directions.

The physics of general relativity does permit a hypothetical universe that curves back on itself in the way you describe, and if it were small enough, we could indeed see ourselves. But I don't know whether stars and planets could evolve in such a universe.

Incidentally, it doesn't have to even have curvature to wrap around as you describe. The universe could be like the game Asteroids, where you wrap off one edge and come back on the other. That has the topology of a torus, but is geometrically flat -- for instance, the angles inside a triangle still add up to 180 degrees.

But it doesn't look like our universe is like that.

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  • $\begingroup$ @KeithThompson thanks for letting me know,I have deleted my comment and you also please delete yours $\endgroup$ – SpringLearner Jul 24 '15 at 4:23

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