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My question is simple:

Can attractive and repulsive gravity (the expansion of space between masses, caused by the still hypothetical dark energy, so it seems they are repelled while in fact, they stay at the same place, like the well-known raisins in the rising bread) be separated or are they interdependent? In other words, can repulsive gravity exist without the attractive type and vice-versa? Of course (according to mainstream physics), on a cosmic scale, both kinds don't interfere with each other and can exist happily and independent of each other. But how was this situation, say, before inflation?

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    $\begingroup$ What is "repulsive gravity"? $\endgroup$ – ACuriousMind Apr 17 at 16:52
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    $\begingroup$ What do you think "repulsive gravity" is? $\endgroup$ – knzhou Apr 17 at 16:57
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    $\begingroup$ You probably refer to dark energy verses matter as a repulsive and attractive gravity. If that so, they both exist in the same Einstein equation, and this is why they "live" together... $\endgroup$ – Noam Chai Apr 17 at 16:57
  • $\begingroup$ Repulsive gravity is the expansion of space between masses so it seems they are repelled while in fact, they stay at the same place (like the well-known raisins in the rising bread). $\endgroup$ – descheleschilder Apr 17 at 17:04
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    $\begingroup$ @descheleschilder: Please edit the question to make it clear that that's what you mean. Nobody is going to guess that from the current text of the question. $\endgroup$ – Ben Crowell Apr 17 at 17:24
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While it seems that OP is mainly interested in cosmological solutions, there is an interesting case without cosmological constant/dark energy where both repulsive and attractive gravity is present around an isolated massive charged body: overcharged Reissner–Nordström metric, when electric charge $|Q|>M$ (in GR units). There we have a region of repulsive gravity when $r<Q^2/M$, test mass would be pushed away from the center, while outside (at $r>Q^2/M$) there is a region with normal, attractive gravity. Thus a point mass could “hover” at an equilibrium radius $r=Q^2/M$. So, this example demonstrates that yes, repulsive gravity (when present) is interconnected with attractive.

A possible realization of this metric with a thin charged spherical shell with somewhat reasonable equation of state is considered here.

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  • $\begingroup$ But isn't the repulsive gravity, in this case, an illusion, of which the electrical forces are responsible? $\endgroup$ – descheleschilder Apr 17 at 22:43
  • $\begingroup$ The point mass here is an uncharged particle, feeling only the metric, not the electrical field. $\endgroup$ – A.V.S. Apr 18 at 3:31

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