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Hello everyone!

I've been sitting here for the past hour extensively rewriting a setting because I ran into an issue with mapping. I had a setting built off the good 'ol concept of a dyson sphere world. By this I specifically mean, a world on the inside of a dyson sphere, similar to an inverted world. But when I was mapping the size of the world it got out of hand, even using a blue dwarf or similarly "minimal sized star". The sphere encompassing the star was just beyond the realms of reasonable for the size of world I want to work with, as I plan on detailing much of the land masses.

So I'm kicking around the idea of using a neutron, pulsar, or magnetar as the size of those work perfectly for what I have planned. I have figured out a way to explain away the whole radiation killing everything and magnetic field killing everything and temperature being far outside the realms of any sort of livable condition in a somewhat believable way. But I can't get past this whole "hundred billion times normal gravity thing" and was wondering if anyone knew any concepts I should explore in search of a solution to this issue. Currently, everyone would simply fall into the sun and the sphere would implode under that amount of gravity. Fantastical concepts are fair play, this is in a science-fantasy world with elder space gods & other good stuff. I'm just trying to figure out gravity nullification concepts for this, if it's even possible.

I've already considered several ideas and done a good bit of preliminary research such as standard anti-gravity fields and the concept of rotating at a high speed to counteract the gravity, but nothing showed up on nullifying something with gravity this intense.

I'm looking for suggestions on ways to explain the idea of nullifying the gravity of a neutron star in a semi-believable way.

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    $\begingroup$ Welcome to Worldbuilding. Please take the tour and visit the help center to better understand this community. $\endgroup$ – L.Dutch - Reinstate Monica♦ Oct 4 '18 at 4:56
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    $\begingroup$ Yes, I've already come up with something to explain that. I'm simply focused on the gravity aspect currently. $\endgroup$ – Ryan Braden Oct 4 '18 at 5:12
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    $\begingroup$ You should revise your physics. A Dyson sphere does not exert any gravity in its inside (shell theorem), and on the outside the gravity may be less than Earth's. $\endgroup$ – Renan Oct 4 '18 at 6:30
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    $\begingroup$ @Renan what do you mean? $\endgroup$ – Ryan Braden Oct 4 '18 at 6:44
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    $\begingroup$ @RyanBraden Renan already mentioned it. It's the shell theorem. When a physical body is inside a hollow sphere, the sphere does not exert any gravitational force on that body. That means, if you nullify the gravity of your star, people will just float in a gravity free space inside the sphere. And if you don't, they just fall into your star and die. $\endgroup$ – Otto Abnormalverbraucher Oct 5 '18 at 14:25
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This has been pretty well covered in the comments on your question by @Renan and @Otto Abnormalverbraucher, so credit where credit is due, but I thought it deserved its own answer.

Net gravitational force in a spherical shell is 0

This is a well established concept in physics. At any point inside a spherical shell (which your Dyson sphere is), one will feel no gravitational attraction to the inner surface of the shell.

Give it a whirl

One way to simulate gravity inside the Dyson sphere is to spin it to create centrifugal "force." This will create a sensation of gravity towards the inner surface. The simulated gravity will be weakest where the axis of rotation meets the Dyson sphere (poles), and strongest at points furthers from the axis of rotation (equator).

Sharing space

If you want gravity in your inverted world you will need spin (presuming you don't handwave this). If you also share space in the Dyson sphere with a neutron star, you can counteract the gravity of the star by increasing the spin to counter that. Note that you will have major differences across the inner surface. If traveling from the "equator" (where gravity is outward towards the Dyson sphere) towards the "poles" (where gravity is inward towards the neutron star), one would eventually reach a point where the gravity shifts from outward to inward and fall into the star.

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  • $\begingroup$ Not gonna lie I made this account, and I've already found an answer within spiderman 2's tritium bs stuff, but I'll definitely rely on the concepts you explain here as a jumping off point to expand my knowledge on this. Appreciate you taking the time to answer my question. $\endgroup$ – Ryan Braden Jan 31 at 21:55
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You want to build a dyson sphere around a neutron star and you want to devise ways to neutralize its strong gravitation. Presumably, because high gravity will make life extremely uncomfortable for the inhabitants of the dyson sphere.

This answer will suggest two things. One, you need to rethink your dyson sphere, but only slightly. Two, forget about gravitational nullification because it's not at all necessary.

Instead of living on the inside of the dyson sphere its inhabitants can live on its outside. If the surface of the dyson sphere is at the correct distance from the surface of the neutron star it will have a surface gravity of one gee. This is same amount of gravity as found on the surface of good old planet Earth. Also, the dyson sphere will act as a shield to radiation and intense magnetic fields surrounding the neutron star.

This type of dyson sphere has been modelled for white dwarf stars. To use a neutron star as the primary gravitating body around which a dyson sphere can be constructed is but a step up.

The relevant paper is Dyson Spheres around White Dwarfs (2015). Its authors are Ibrahim Semiz and Salim Ogur. Copies can be downloaded from the link above.

We point out that Dyson Spheres could also be built around white dwarfs. This type would avoid the need for artificial gravity technology, in contrast to the AU-scale Dyson Spheres. In fact, we show that parameters can be found to build Dyson Spheres suitable --temperature- and gravity-wise-- for human habitation.

Obviously building a dyson sphere a neutron star will technically more difficult to accomplish than building one around a white dwarf. But it is reasonable to assume that technology will advance to the point that doing the same for neutron stars to become feasible.

A neutron star dyson sphere will not need either artificial gravity technology or gravity nullification technology. The dyson sphere only needs to be built at the correct distance from the neutron star where the effective gravity will be one gee.

In conclusion, this answer argues for the proposition that while the querent believes that gravity nullification is necessary for a neutron star dyson star, this isn't needed at all.

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    $\begingroup$ Possibly the most polite ending to a frame challenge answer I’ve ever seen. +1 $\endgroup$ – Joe Bloggs Oct 4 '18 at 9:05
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    $\begingroup$ If it's further away, it's bigger, which negates op's reason for choosing a neutron star. $\endgroup$ – Aethenosity Oct 4 '18 at 9:55
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    $\begingroup$ I think the point of choosing a Dyson sphere was that OP wanted an inside-out world. $\endgroup$ – Real Subtle Oct 4 '18 at 10:28
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    $\begingroup$ @RyanBraden Excellent! I am delighted you are going to read the paper. It's an absolute gold mine of information about Dyson spheres. Highly recommended. You don't need to worry about absurdly large landmasses. On the outside you can have large numbers of reasonably large landmasses & lots & lots of small ones too. You're welcome to stay with your original idea. This was an alternative approach. New perspectives can be extremely useful. Keep your options open & do what you think is best. $\endgroup$ – a4android Oct 5 '18 at 4:50
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    $\begingroup$ One gee, wow! If you find a suitable binary pair, you could even have a Sun in the sky, and day-night cycle. Spin the sphere just right and you could fine-tune the cycle to 24 hours. I'm getting nostalgic. $\endgroup$ – Emilio M Bumachar Nov 1 '18 at 18:24
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I don't think this idea would work too well because tidal forces (difference in gravity with respect to distance) around neutron stars are very strong, so if the Dyson sphere got out of balance the increased gravity on one edge would be catastrophic. If you had some very powerful ion rockets they could maybe ensure stability (can't remember the novel where I first read this idea).

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