If our universe was a zero-energy universe, what would happen if someone would transfer energy / matter or bring objects from parallel universes to our universe? What would be the consequences?

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    $\begingroup$ I recently asked a question about matter from another universe, the answers and comments may be of interest worldbuilding.stackexchange.com/questions/179105/… $\endgroup$ Jul 24, 2020 at 20:01
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    $\begingroup$ I highly recommend Dr. Asimov's excellent book " The Gods Themselves" which in large part deals with exactly what your question asks. See: en.wikipedia.org/wiki/…. $\endgroup$
    – Joe
    Jul 24, 2020 at 20:48
  • $\begingroup$ There is a theory that if we understand enough of the universe, it grows more complex. Maybe it happens here too. But as it's all unknown, any matter or energy will behave as you want it to behave. $\endgroup$
    – Trioxidane
    Jul 24, 2020 at 20:50
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    $\begingroup$ @Joe I totally agree, it is a brilliant book. $\endgroup$ Jul 24, 2020 at 21:34
  • $\begingroup$ It entirely depends on the nature of the other universe, and the laws of physics there, and the form that matter/energy takes there. $\endgroup$
    – cowlinator
    Jul 25, 2020 at 0:33

2 Answers 2


Since direct interaction with parallel universes is totally out of bounds for current science, you can basically do whatever you want. Make up your own laws, because we currently have no way of scientifically determining what would happen in such a scenario.

If you’re completely stuck, here’s an idea for a way to preserve the zero-energy property of separate universes while still allowing matter transfer:

  • The process of transferring matter from one universe to another requires as much energy as is stored in that matter, as calculated by the formula $E=mc^2$ (and this consumed energy is released into the universe from which the matter was taken).
    • Pro: this would mean that each universe maintains the zero-energy property, which is nice.
    • Con: moving even microscopic objects between universes will require an astronomical amount of energy, which probably isn’t feasible.
    • Pro: although moving matter between universes will be hard, you can certainly transfer information much more easily. So you might be able to Zoom with someone in an alternate universe, but not meet them in person.

If you transfer it through a GR wormhole, the consequence is that the wormhole mouth on your end gains negative mass to balance the positive mass of the stuff you are bringing in, while the mouth on the source end gains positive mass. If you don't keep the flow of material roughly balanced in each direction, the source mouth will eventually be enveloped by a black hole, turning the destination end into a white hole, and you will only be able to send material and information one-way.

My recommendation would thus be to not try to import large amounts of energy, but merely to import sources of low entropy, and dump your high entropy waste back into the other universe to balance the books.


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