We are using a Morris-Throne Wormhole Metric. Let's presume the throat of this wormhole (in internal hyperspace) is short, let's say 1km.

Now, as you are travelling through the entrance wormhole, your speed is ~0 relative to the movement of the galaxy, however, you are moving through the throat onto a piece of mass (Earth) travelling at 107,000km/h relative to the galaxy. There would also be a sudden increase in galaxy-relative rotation (empty space with 0 rotation -> Earth with 460m/s). How would this transition occur? My current guess is an increase of local speed relative to the galaxy occurs during the movement throughout the throat.

Apologies if this question is hard to answer, but it only occured to me recently that this "transition" between empty space (space moving at no speed relative to the galaxy) and curved spaces (space with great local mass such as on a planet that is moving relative to the galaxy) is the reason why wormholes must be maintained many AU away from the centre of a system. In my world, wormholes are positioned in positions around their local star so that their velocity and rotation is equivalent to the other mouth. (1 wormhole 5 au around the star at 500,000km/h, another wormhole 8 au around a larger star at 500,000km/h)

  • $\begingroup$ I'm not quite sure what you're asking: can you clarify "flat" and "empty" with regards to space; and also what you mean by changing your rotation and velocity? $\endgroup$
    – elemtilas
    Commented Apr 30, 2020 at 6:37
  • $\begingroup$ Will add to the question now, apologies. $\endgroup$
    – MrKred
    Commented Apr 30, 2020 at 6:38
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    $\begingroup$ This would only be answerable in a way consistent with how your worm-holes work, and since no real-life wormholes are around to observe it must be the author's decision how they work. We need more of a clear idea of what you are trying to achieve, so, could you supply more details of what you are hoping would happen - or - tell us the rules of how wormholes behave in differing gravity wells. We can help you solve specific well-defined problems, but idea generation is more of a subject for worldbuilding chat. $\endgroup$ Commented Apr 30, 2020 at 7:12
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    $\begingroup$ @ OP: I see that the question got closed, and I started the process to reopen it. $\endgroup$ Commented Apr 30, 2020 at 13:31
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    $\begingroup$ What's the rationale for closing this question? This site has plenty of questions about wormholes that aren't closed, and this one went to the trouble of linking an actual, precise scientific paper describing the GR wormhole solution they're using so it's very answerable (in fact I was planning on doing so once I had a bit more time to go through the linked paper). $\endgroup$ Commented Apr 30, 2020 at 13:34

1 Answer 1


Everything dies.

I have already given some answer in this site about wormholes, and I don't tire of reminding everyone that these beasts have mass. Even a very small one can be more massive than Earth - a one meter wide one would have a mass like that of Jupiter. Check this other answer for more details.

Anyway, suppose someone manages to jump through the mouth in interstellar space. They'll take anywhere between a moment and a few months to exit at the other side (regardless of throat length). The other side will contain the debris of what once was Earth, which will be orbiting the wormhole mouth.

The person will come out of the wormhole mouth fast as a bat come outta hell, in an escape trajectory of the sun. The higher probability is that it will miss all debris and will eventually leave the solar system. Less probable will be hitting some rock at a few kilometers per second, which probably results in instant death. The corpse might either orbit the sun or the wormhole, depending on how the impact changes their speed.

As for speed variation - it's all relative to the wormhole. They would exit it at the same speed they entered it. Keep in mind that since the wormhole is pretty massive, it will accelerate anyone approaching it. A ~1 meter wide wormhole will have a escape velocity of around 59.5 km/s at around one jovian radius from its "entrance", much higher at the mouth itself. What this means is that when you come around 35,000 km from a mouth, your speed will be at least 59.5 km/s relative to it. May be greater, but not smaller than that.

This also means that when you exit on the other side you will decelerate, and by the time you are 35,000 km from it you will still be going at 59.5 km/s in the very least (relative to the wormhole). Since the escape velocity of the sun around 1 AU is in the order of 42.1km/s, this effectively means it's a matter of time until you either fall into the sun or exit the solar system altogether.

  • $\begingroup$ Thank you so much; this was a great answer! I'm very interested in keeping my fictional wormholes as realistic as possible. Could you link any articles of sites that may help me apply the maths you've done here to other examples? Also, do you know how far away from a solar system a wormhole would have to be to be safe to travel through? orionsarm.com/eg-article/48545a0f6352a < That article has been a good help, if you don't mind, I'm curious how accurate it is. I'm sorry for asking so many questions haha, you don't have to answer all (or really any) of them. $\endgroup$
    – MrKred
    Commented May 1, 2020 at 3:01
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    $\begingroup$ Actually, I've just noticed in your other answer you linked that wormholes require exotic mass on the scales of Jupiter. Despite this, many metrics (such as the Morris-Thorne-Kuhfittig metric) have been created that require arbitrarily small quantities of the mass. Assuming this is possible, surely the mass of the wormhole would be much, much smaller, and therefore be easier to traverse. $\endgroup$
    – MrKred
    Commented May 1, 2020 at 3:09
  • $\begingroup$ Also, in terms of wormhole throat length; I have seen the answer you linked to me before, I have also read many wormhole papers myself, and I'm fairly certain that the energy distribution effects the length of the throat, while the speed you travel through that length determines the ultimate traversal time. $\endgroup$
    – MrKred
    Commented May 1, 2020 at 3:16
  • $\begingroup$ @MrKred I'm glad to see you are as into wormholes as much as I am. If you've seen my links and if you've found more about tveir metrics and mass, then you are ahead of me in research :) I would like to read about not-so-massive wormholes and variable traversal times. I'll do some research this weekend! $\endgroup$ Commented May 1, 2020 at 5:03
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    $\begingroup$ No problem mate : D Wormholes are immensely fascinating mathematical artefacts and I think are likely humanities best bet at FTL travel if possible. arxiv.org/pdf/0908.4233.pdf < This is the link to the Kuhfittig Metric and the Orions Arm article (despite being fiction) contains a lot of very accurate maths and predictions. I love the idea of an interstellar highway of trams travelling through nanotube cylinders hundreds of kilometres long that lead through nodes of wormholes across the galaxy. $\endgroup$
    – MrKred
    Commented May 1, 2020 at 6:28

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