I'm revisiting an old worldbuilding project of mine where enormous, Lovecraftian monsters arrive at Earth through a wormhole with one endpoint embedded in Jupiter's atmosphere, and I'm unsure about some of the specifics of the cataclysm.

The wormhole appears on Earth over the middle Pacific at sea level, with the other endpoint in Jupiter's "upper" atmosphere, altitude ~180 km "deep" at about 20 atm of pressure. The wormhole has an aperture diameter of ~200 meters; throat length shouldn't matter I'd think, but if it does, let's just go with the same as the diameter.
The wormhole lasts for some amount of time before being destroyed. What I'm looking for is a mass-extinction event, not a catastrophe that totally, irreparably destroys Earth's biosphere and all life in it. (There's a knife's edge difference between a large-scale extinction and a total extinction. Mass-extinctions are usually characterized by 75% of organisms perishing, so I'll leave it up to your intelligent discretion to decide what extent of harm may be done to Earth to affect that.)
I don't know how to gauge that potential duration of the wormhole--hydrogen and helium, the main constituents of Jupiter's atmosphere, would easily float to the top of Earth's atmosphere. Hydrogen would also be extremely combustible in our oxygen-rich atmosphere. How much is too much, how long is too long? How long should Earth's heroes wait before destroying the wormhole to only cause a mass-extinction?


3 Answers 3


Choked flow comes into play at 2.13 atmospheres. Mass flow through the wormhole will be 141 tons of material per second, if I’ve done the math correctly.

The material is hot (150 C), but not stupendously hot.

Earth has 5.5 quadrillion tons of atmosphere. To mix 1% of Earth’s atmosphere at 141 tons per second will take 1.2 million years.

But you can see how the calculations would work for your characters to calculate a value, whatever it is.

  • $\begingroup$ Huh, that's almost unbelievable! You're telling me there could be one of these portals on Earth right now, and it wouldn't be a cause for immediate worry? Also, if you don't mind (and I believe it would improve your answer hugely), could you provide the math/tools you used for your calculations? Thank you for your answer $\endgroup$
    – BMF
    Dec 27, 2021 at 13:30
  • 1
    $\begingroup$ @bmf it will be a little while to get methods. I stole this from a calculator I wrote to answer a very similar question about hellscapes (which does have all of the derivation, but not the Jupiter specifics). At the moment, I’m the only healthy person looking after a house full of sick family, so I’m not able to do much. $\endgroup$ Dec 27, 2021 at 14:07
  • 1
    $\begingroup$ @bmf - here’s the similar question with the derivation in the answer worldbuilding.stackexchange.com/questions/177711/… $\endgroup$ Dec 27, 2021 at 14:11
  • 1
    $\begingroup$ I used 1.4 for gamma $\endgroup$ Dec 27, 2021 at 14:23
  • $\begingroup$ Short answer: we will kill ourselves way faster with the atmosphere we are already adding through fossil fuel combustion than from this portal. $\endgroup$
    – Nosajimiki
    Dec 28, 2021 at 15:04

Stealing from James McLellan's answer, the flow rate of Jovian atmosphere through a 200 meter portal won't cause any large scale extinctions anytime soon. Even if the answer is off by a couple of orders of magnitude, the Lovecraftian horrors are going to need to gobble up Earthly life at a prodigious rate if you want your heroes to see a mass extinction before they die of old age.

On the other tentacle, the job contract for getting that portal closed doesn't specify doing it just in time to save 25% of Earth's species. Instead, the job is to figure out how to close it and execute the plan as quickly as possible. Maybe this requires a nuke. Maybe it requires some hideous blood sacrifice. Maybe it requires the "Open monster spewing portal from Jupiter" passage in the Necronomicon to be read backwards.

There's a small complication. Once the heroes have an idea of how to do it, they don't get to spend a lot of time practicing. Any instructions, be they from ancient scripts or from the Miskatonic University's specialist in trans-dimensional physics, aren't going to be as clear cut and foolproof as the instructions on a can of condensed soup.

So, while the world is focused on dealing with the monsters, our brave heroes slip in to close the portal. They launch the missile, press the activator on the dimensional scrambler, use sacred blades to carve the hearts out of 1000 armadillos, read the opening instructions backwards, or whatever. Then what happens?

A. Portal goes poof. Heroes get a parade. Roll credits.

B. Nothing. It was a great idea in theory, but it didn't work. Time to try a different method.

C. The portal closes. High fives and hugs begin, but then the portal reopens. Due to some tiny error in the closing method, the reopening portal doesn't stop at 200 meters or even 2 kilometers. Instead, it slowly widens to 200 km.

The end result of option C? The much larger portal unleashes far more creatures and seriously alters the composition of Earth's atmosphere. Even more interesting, the lower half extends downward past the crust into Earth's mantle, and that rock is hot, under extreme pressure, and not solid. A significant amount of mantle material will be sprayed into Jupiter's atmosphere, likely causing significant geological instability on the Earth side of the portal (and seriously annoying the leaders of the Lovecraftian horrors). Conveniently, the new version of the portal isn't stable, so the author can have it collapse at the desired level of destruction.

Congratulations heroes! You've sort of saved the Earth.

Edit: I jst thought of one ugly little detail. If that 200 km wormhole is over land, things mostly go as explained above. But what if most/all of it is out over the ocean. Then the lower half won't just bu nibbling crust above the magma spraying into Jupiter's atmosphere. The expected 20 or so atmospheres of pressure on the Jupiter side will push the water back until a bit short of 200 meters depth (might be off a bit here, working from memory and doing the math by counting on my toes). Below the pressure balance point is an area about 200 km wide extending to the ocean floor. That's now a river draining the Earth's oceans. A day or two should undo that pesky sea level rise problem, but if it stays open too long, you can add "major sea level drop" to the list of problems pushing species into extinction.

Ocean, land, or some of each, the forecast also calls for interesting volcanic activity. 😃

  • 1
    $\begingroup$ Lol, I asked how long the heroes must "wait" so I can structure the plot so that the heroes conveniently arrive at the solution at just the right time--they aren't actively malignant by waiting 'til the last moment. If James' calculations are right, the heroes can punch out and take a life-long vacation (which I almost can't believe...) $\endgroup$
    – BMF
    Dec 27, 2021 at 13:27
  • $\begingroup$ @BMF - Heroes show up in the nick of time so often that I do sometimes wonder if they are hanging back to make their actions seem more dramatic. "Oh look, the press is here. Let them get their cameras set up and then we swoop in to save the day." 😆 $\endgroup$ Dec 28, 2021 at 13:02

When you inject hydrogen into Earth's atmosphere, it will be oxidized to water, or water vapor, depending on temperature. Prepare for a lot of rain and a sealevel rise ? if you don't want the apocalypse, matter must be gently dropped on the planet, with 141 T/sec indeed. But I wonder how that could be achieved, in a science-based way, using a wormhole.

Sorry I have to shoot at your plan with this answer, but...

Would a science-based wormhole actually transport matter ?

I wonder if a space-time wormhole can behave like a vacuum cleaner, that is provide a pipeline, to dump Jupiter matter on Earth. Matter will certainly evaporate, ionize, be squeezed, degenerate, fuse back into normal matter, then maybe unsqueeze and condensate on the other end, in some shape ? and that's a best case scenario. No monsters will travel through a science-based wormhole alive. The gradient of spacetime inside your 200m wormhole would crunch them, before entrance.

On either side, a black hole is perceived

On either side, there will be some kind of gravitational attractor, or something perceived as an attractor. Your space-time curvature bends (is forced) into a certain direction. You travel along in that direction, "falling into" the wormhole. What happens next, there are three models to choose from: you could assume a white hole to exist on the other end, with negative gravity. Another model proposes to place two black hole attractors, on either side of the worm hole. Your traveller would actually have to escape a crash two times: once on entry and once on arrival.. A third model may place the black hole attractor in the center of the wormhole, resulting in a wormhole sucking travelers in on either side, providing no way out. In that case you don't want to have that thing hanging above the pacific, we could loose an ocean.

Wormhole diameter

Another nasty aspect of travelling through worm holes is the centrifugal force of your spiral path through the wormhole. Theoretically, your width is not 200m, it could be anywhere downto Planck length. Handwaiving size and proportions of singularities and keeping your diameter at 200m, the matter will stay on the surface of space time, which is the wand of the wormhole. You can't be "inside" a wormhole, because no space-time exists there.

Is travel through a wormhole effective ?

You'll be on a the wand, entering at some angle.. causing a spiral path. There will be no means to travel faster than the speed of light, along that wand, let alone through the center, where space-time is absent. As a result, you could spiralize along your 200m cylindrical wand with a velocity near c, while traveling forward much slower. The net forward move may be a fraction of your actual speed. Science-wise, your Jupiter monsters could take centuries to reach Earth.

  • $\begingroup$ Thank you for your answer, but I'm not interested in science-based descriptions of wormholes. It's best not to attempt explaining things like wormholes or FTL with physics, because they grossly, blatantly defy it. (And the results aren't very fun.) For story-telling sake, I'll explain how I want it to behave, regardless whether such a thing is physically possible. $\endgroup$
    – BMF
    Dec 27, 2021 at 20:03
  • $\begingroup$ Also, combusting H2 in an O2 atmosphere (with a watery result) is highly energetic, is it not? $\endgroup$
    – BMF
    Dec 27, 2021 at 20:05
  • $\begingroup$ @BMF You want your monsters to invade Earth safely through that wormhole, but alas.. can't offer that to you. I've put a critical answer because you used a "science-based" tag. And yes, you can expect some release of heat, when you release a large amount of hydrogen at once in the atmosphere. It would depend on ignition of the hydrogen, e.g. by lightning. But the presence of a wormhole on less than a km from the surface will imho have far graver consequences than a few sparks and a splash of water. $\endgroup$
    – Goodies
    Dec 27, 2021 at 20:29

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .