Does energy remain conserved in each of the 'universes' of a maximally extended black hole-white hole system (Kruskal coordinate system)? Referencing from Wikipedia: "This means that the interior black-hole region can contain a mix of particles that fell in from either universe (and thus an observer who fell in from one universe might be able to see light that fell in from the other one), and likewise particles from the interior white-hole region can escape into either universe." White Hole Does that mean black holes can 'leak' energy into another 'universe' via a white hole, and energy does not stay conserved in a particular universe? If that is correct, can't we say that white holes definitely does not exist since starts fallen into a black hole add to its mass/energy, rather than leaking into another universe?

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    $\begingroup$ In the reference frame of an outside observer in either universe it takes infinitely long for anything to cross the horizon, while the escaping into other possible regions only happens after the horizon crossing, so if the energy goes from here to there it does so only after the end of times (though in a final proper time), and since there is no end of times there is no loss or gain of material in either universe, see youtube.com/… $\endgroup$
    – Yukterez
    Dec 14, 2022 at 18:39


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