In my fictional universe, after experimentation with quantum field manipulation, a way to open, expand and stabilize wormholes is developed, requiring an immense flux of energy (as manipulating quantum vacuum is extremely inefficient) in a machine called a phase-gate, powered by a small dyson sphere.

Two of these phase-gates could be constructed in neighboring star systems and be used for virtually instant travel, after said star system is colonized and a sizable dyson sphere is built. After around 6 decades after the first antimatter-powered long-hauler starships were launched, and made the almost 40 year crossing at 0.7C, the two star systems were linked by a phase-gate and became one of three habitable systems humans have colonized.

During a conflict that forced most of humanity off of a ravaged earth and to a pre-terraformed planet, part of the contingent (the protagonist and his team) is hurled through the (sabotaged) phase-gate after being attacked, and the machine is destabilized on the earth-end, causing the gate to uncontrollably collapse into two black holes with the mass-energy equivalent (each) of about Mount Everest. (Stranding the protagonists on a deserted star system with no easy way home.)

How big would the explosion be as these two black holes radiate away their energy (hawking radiation) and how long would it take (I.E. how fast would the thing explode).

Im going to assume that either way, the machine is completely vaporized or utterly destroyed, beyond repair, and the main conflict in that part of the book is to rebuild this epic megastructure and try to contact the new-terra colonies to open THEIR gate.

Is this idea even viable? Im trying to aim for being soft-science fiction, as the story does take SOME scientific liberties, but it's roughly accurate. (Long-haul ships that are massive antimatter annihilation engines and radiator rigs, towing a kilometer long truss and pulling a couple hundred tonnes of 3-d printers, a small crew and plans for the gate, ships follow brachistochrone trajectories for gravity, sizable dyson spheres and orbital momentum tethers for propellent-less interplanetary transit.)

EDIT: Thank you for the replies, and I made a mistake in phrasing my question. How much and how would a collapsing wormhole release energy, as the tunnel in spacetime caves in and forms two singularities, and how much energy would those singularities release. (Im assuming that those primordial black holes are still technically the wormhole and therefore still count as energy the wormhole is releasing as it falls apart)

EDIT 2: I also should have specified what I mean by "small dyson sphere". When I said that, I meant a dyson sphere that produced dozens of exawatts of power, a minuscule fraction of the suns total output, in the ballpark of tens of thousands of exawatts (don't quote me on that one, I didn't check). For our "modern" standard, that is still an absurd amount of energy, but not unthinkable for a humanity a couple hundred years ahead of us.

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    $\begingroup$ Hello @SamKitsune, welcome to Worldbuilding. For future reference: (a) You are allowed to ask one and only one question. (b) Wormholes are 100% theoretical, so it's 100% storybuilding what will happen to them. However, your title appears to not ask the question your post does. Your post is asking what would happen when two black holes evaporate, which has nothing to do with the backstory involving wormholes. (c) It helps if you clearly separate your backstory from the question you're asking. (d) Since wormholes are 100% theoretical, asking if the idea is viable is meaningless. ... $\endgroup$
    – JBH
    Dec 26, 2022 at 1:25
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    $\begingroup$ ... A quick Google search about Hawking Radiation discovers, Hawking "showed that they shrink incredibly slowly and eventually explode in a flash of gamma rays." That's not a traditional explosion and "incredibly slowly" might suggest that you can pick whatever time you want for your story (see narrative necessity. Could you edit your post to present one question, be sure the title and post have the same question, and be clear about what you're expectations are? Thanks! $\endgroup$
    – JBH
    Dec 26, 2022 at 1:28
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    $\begingroup$ You're telling us that colonists built a "small dyson sphere" in the second star system in just 20 years? If that's true, this civilization clearly has no problem manipulating absolutely ludicrous amounts of energy, and I would not expect them to worry about the energy released by a single cosmic event like wormhole collapse. $\endgroup$
    – Tom
    Dec 26, 2022 at 3:18

1 Answer 1


Probably gravitational waves

It really depends on how your wormhole physics work. Research in the area of physical wormholes is very scarce, being so esoteric.

I frequent forums where physical wormholes and "warp drive" space-time metrics are sometimes discussed. I'm not going to be able to cite any of this, so take it with a grain of salt.

Under the Visser model of wormhole collapse, when two wormholes fall "out of configuration" a closed time-like curve (CTC) has the potential to form, but is averted due to runaway quantum resonances. Essentially, when the CTC is formed, a photon may travel around the closed topology and come to constructively interfere with itself in the past. This new doubled photon then heads around the CTC and interferes with itself again, and again, etc. This is the case for all forms of quantum fluctuations via vacuum polarization, and not just light. In the Visser model, the minute fluctuations in vacuum resonates and explodes in zero-time, either repelling the wormholes apart (due to metric weirdness), or creating a major instability in the wormhole structure leading to both wormholes collapsing.

Due to a lack of data on potential ANEC-violating, negative stress-energy "materials" needed to construct a wormhole, the radiation released from collapse is not investigated. Personally, I would expect the collapse to be brief (measured in microseconds) and radiate mostly gravitational waves. Possibly a large fraction of the energy content of the original wormhole. You might also get a huge gamma flux as well. If anything were to be stuck in the wormhole during collapse, and depending on throat geometry and how much of the spacecraft isn't swallowed by the black holes, you'd definitely get some gammas and possibly relativistic jets of ship debris at both ends.

Gravitational waves will mostly go through matter without doing much harm to it. Black hole mergers, converting whole solar masses into pure gravitational waves, would be largely harmless at millions of km out. Two mountain-mass wormholes collapsing is nothing in comparison.

Also, as a bit of a critique, you mention that part of your story involves rebuilding the destroyed megastructure to "open their gate". Commonly in "hard" sci-fi (as hard as sci-fi with wormholes can get (see John J. Lumpkin's "Human Reach" novels)), wormholes are "plucked from the quantum foam" in pairs, both wormholes right next to each other. This is mostly expected because physics acts locally. Basically, it's a little unlikely that we'll be able to "open a wormhole" to any ol' where in the cosmos. They'll be created as pairs, and then separated, stabilized, enlarged, etc., and then one wormhole end will need to be transported to the destination, mostly by STL means. However, if you've got an existing wormhole network, FTL transport of the newly-created wormholes through it is doable and has its upsides in regards to time dilation management, as the new wormholes assume the time dilation of the existing acyclic network, reducing possible CTC formation.

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    $\begingroup$ Wow, thank you! I realize I didn't structure the question properly but I got the answer I needed. I was expecting bursts of energy I.E. gamma rays, and possibly some other nasty kinds of radiation, but it wouldn't matter that much as the only thing I was concerned about was the machine built around it being wrecked. (it would probably be torn apart and eaten by the primordial black hole left over.) $\endgroup$ Dec 26, 2022 at 19:50
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    $\begingroup$ @SamKitsune I didn't answer the exact question you were asking, "how much energy", but I think you'd be totally justified in saying the wormhole collapse creates tons of gammas and totally destroys the supporting armatures. Truth is that there are too many variables and unknowns to be specific about anything. Wormholes are very speculative. $\endgroup$
    – BMF
    Dec 26, 2022 at 21:21
  • $\begingroup$ I didn't actually specify, but its never explicitly said that the phase-gate is a wormhole, it just follows the rough outline of the gates in "The Expanse" by James SE Corey, so I do have the liberty to say it will do whatever I want it to do, given that the book is mostly taking real science and making it pretty or simplified and easier to understand, as the core of the book is its drama, more so than its science. $\endgroup$ Dec 26, 2022 at 21:32

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