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Is it possible to infer information about the structure of the universe beyond the observable one, by observing its effects on the parts we can see? Can for example gravity from sources we cannot see affect objects which we can see, and allow us to calculate the mass or directions of the source?

Innovine
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  • If we see effects in this universe that we can't explain, we're better off looking for effects in this universe, and including whatever we find in the definition of "this universe". – Chris B. Behrens Nov 29 '21 at 15:57
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    I am not sure this question can have an answer in Space Exploration. – Ng Ph Nov 29 '21 at 16:15
  • What you have described is precisely the reason astrophysicists think "dark matter" and "dark energy" exist. Google those terms, read about galaxy rotation curves, and then consult Physics SE. – Ryan C Nov 29 '21 at 17:26
  • The whole concept of "outside" the universe is a bit of a fuzzy concept. Roughly speaking, there is only an inside, not an outside to it. The concept of "outside the universe" is as undefined as the concept of "what happened before time began" – CuteKItty_pleaseStopBArking Nov 30 '21 at 09:52

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Is it possible to infer information about the structure of the universe beyond the observable one, by observing its effects on the parts we can see?

Quite simply, no. "Beyond the observable universe" is, by definition, so far away that the spacetime between us & it is growing faster than the speed of light. No information can outrun this expansion, and thus no further information about the state of that universe can ever be received by us. There are no effects of the non-observable universe on the observable one.

However, we can make observations about the past of what is currently "beyond the observable universe". Why is this the case? Because that information already arrived at our position. Indeed, the observable universe is shrinking as the expansion of spacetime accelerates. Objects very far away we can observe--not at their "present" state, but from their very old light. As the observable universe shrinks, these objects will exit the observable universe, and we will receive no more information about them.

This leads us to some conclusions: because the (very old light from the) margin of our currently-observable universe seems to resemble (what we believe was) the past of the interior of our observable universe, it can be inferred that the universe--both observable and not--is relatively homogenous.

Looking back at the oldest & furthest thing we can observe--the cosmic microwave background radiation--we observe a very homogenous structure (of the universe in the very distant past). Thus, we can assume that all these regions of the universe were once in close contact with each other & reached near-equilibrium. By the cosmological principle, it can be assumed (but never proven) that the non-observable universe is very similar to the observable universe.

Anton Hengst
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