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On the inside of a Dyson sphere there is effectively no gravity. Is there an alternative method to keep people on the inside surface from floating around?

I know it could spin and that would keep them down in a small ring around the equator, but is there a way to apply a 'downward' force equally? Could atmospheric density or buoyancy be reversed? Or maybe a fictional element is required?

It doesn't have to be 1g but the closer the better. To clarify, there is only 1 sphere, people live on the inside, the population is several orders of magnitude more than ours.

Edit: After a few answers, I'm starting to think I might need a graviton controlling element. Any suggestions?

ZoneWolf
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  • If your civilization is powerful enough to develop a Dyson Sphere, it's powerful enough to develop artificial gravity. – RonJohn Aug 03 '18 at 01:53
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    @RonJohn, not necessarily. Artificial gravity (apart from that generated by rotation) is not known to be possible, and therefore even a K2 level civilization may not be able to generate it. – Gryphon Aug 03 '18 at 02:00
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    I suspect the "small ring" around the equator would be large enough to give every person currently living on Earth their own private continent. – plasticinsect Aug 03 '18 at 02:24
  • You could develop a biologic that suctions people's feet to the "ground." Something along the line of the chairdogs from the Dune universe. – JBH Aug 03 '18 at 03:44
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    This is just one reason why Dyson Swarms are preferred over Dyson Spheres. – StephenG - Help Ukraine Aug 03 '18 at 04:11
  • So why can't you just have a double layered dyson sphere? – Aify Aug 03 '18 at 04:33
  • @Aify how does that generate downward force? – ZoneWolf Aug 03 '18 at 04:52
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    A 2 layer dyson sphere that your people on the "inside surface" are really sandwiched between the two layers. The smaller layer acts as the floor (the gravity from the star pulling them towards it) and the outer layer is just there to fulfill the requirement of not being exposed to space (and technically being inside a dyson sphere). "Down" is relative to what direction you're facing, but in this case it's pretty much "force that pulls you towards the surface of whatever you're standing on." By making use of the gravitational pull of the star you can avoid issues like floating into the star. – Aify Aug 03 '18 at 06:55
  • @Aify that defeats the purpose of living on the inside of the sphere. They could just live on the outside. – ZoneWolf Aug 03 '18 at 08:42
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    Hi ZoneWolf. I edited out the last sentence of your question. If you feel that an answer is not helpful, then you can vote it down as not helpful. Part of our be nice policy is to assume good intentions. If you want answerers to pay particular attention to some area, there's no problem with adding something like "answers should elaborate on how they relate to X", but please take care to phrase it in a non-confrontational manner. – user Aug 03 '18 at 09:36
  • And what persay is the benefit to living on the INSIDE of a dyson sphere compared to living on the outside? The whole point of a dyson sphere is to use it to generate energy; by living on the inside, you reduce the amount of energy that can be captured, thus defeating the purpose of a dyson sphere. – Aify Aug 03 '18 at 16:39
  • Habiting planets inside the sphere is ruled out, right? – Rafael Aug 06 '18 at 02:48

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You could spin the sphere, thus creating gravity on the equator and using the remaining internal surface (at 0g) for infrastructure/energy collection. This assumes that the material the sphere is constructed from is infinitely strong, as the forces created are massive.

As this question is posted in Worldbuilding, not experimental physics, perhaps the question should answer itself. There is no way, currently, to justify the creation of artificial gravity inside a sphere. You have built your world in a Dyson sphere; you should accept that zero gravity is part of that world.

Gravity is a pain in the backside anyway. Why would a space-faring civilisation go to such effort when they could just live on the outside of the sphere and harvest energy on the inside?

Imagine how much more interesting your world will be when you can throw a paper aeroplane and take someone's eye a hundred kilometres away. Physics gave you lemons; I say you juggle them - it's much more entertaining than pretending that they are oranges.

Inoutguttiwutts
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    I don't think you understood the problem OP is facing. See, Shell theorem. Essentially one of the things it states is that a spherically symmetric shell (such as a stable Dyson sphere) contributes no weight to objects inside it regardless of where they are. Increasing the mass of the shell has no impact on this fact. – AngelPray Aug 03 '18 at 08:16
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    @AngelPray I don't think you're right in this case. While the center of mass of the total sphere is at the star, mass at the opposite side of the center has less effect on you because you're so incredibly far away and so close to a different part of its mass. The closer you bring two objects, the bigger the effect of gravitational acceleration. With this incredibly large distance and high mass located right next to you, I'd assume it does cause a gravitational effect. But then again, I'm also neither scientist nor mathematician, so I might still be wrong. – Otto Abnormalverbraucher Aug 03 '18 at 08:24
  • The Dyson Sphere you described is exactly what I'm designing. But it has 4 huge oceans that go right through the sphere. The problem is shell theory as mentioned by AngelPray. – ZoneWolf Aug 03 '18 at 08:31
  • @OttoAbnormalverbraucher all molecules of the sphere effect you equally. The other side may be further away but you are being pulled by every part of the shell at once so it all cancels itself out. Thats basically shell theory – ZoneWolf Aug 03 '18 at 08:34
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    The force exerted due to gravity from a uniform shell on any point inside that shell is 0, this was even allude to in the question. Your proposed distance wrt temperature also makes no sense because Earth is only habitable due to a combination of day/night cycles, the atmosphere, and radiation shielding from the magnetosphere. A random spot in near-Earth space is lethal even if everything aside from the levels of visible light is manipulated to Earth level, you would basically be living under the noonday sun 24/7. – Teleka Aug 03 '18 at 08:34
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    Thanks for the link, AngelPray. It's interesting, and I think it does prove what that my logic is flawed. My bad. – Inoutguttiwutts Aug 03 '18 at 08:37
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    Edited to remove Bad Science. There's enough on the net already. – Inoutguttiwutts Aug 03 '18 at 08:47
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    rotating the sphere would produce stress forces which would rip it apart. there's an article by Larry Niven somewhere where he mentions calculations which show that you need unobtainium to construct the ringworld - the argument is the same for a rotating sphere (probably worse) – ths Aug 03 '18 at 09:14
  • True, but doesn't respond to the question. OP has already made the Dyson sphere, probably from Unobtainium, and now needs to safeguard inhabitants from imminent incineration. I say, spin the thing and find out just how strong this mystery material is! – Inoutguttiwutts Aug 03 '18 at 09:21
  • @ZoneWolf I can't wrap my head around the shell theorem right now. I'll have to watch a video explaining it or something when I have time. I'll just accept it for now. – Otto Abnormalverbraucher Aug 03 '18 at 09:26
  • Edited to disparage question in lieu of helpful answer. Great discussion! – Inoutguttiwutts Aug 03 '18 at 09:47
  • @OttoAbnormalverbraucher don't stress too much. It took me a few hours of arguing with mods to start understanding it. – ZoneWolf Aug 03 '18 at 10:06
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Electrostatic attraction.

Usually we think of electrostatics operating on small scales - like cat hair sticking to a balloon. But electrostatic attraction (and repulsion) can substitute for gravity in some situations. I put this idea forth in the linked Planet Walkers question, as a method to keep people who live on little asteroids from floating away.

The Planet Walkers - Feasibility

Electroadhesive robots have been constructed. From What sort of claws would be best utilized for melee combat and quickly scaling the walls of a modern day building?

enter image description here

http://www.hizook.com/blog/2009/08/06/electroadhesive-robot-climbers

By now, most roboticists are familiar with the myriad gecko-type robots that employ Van der Waals forces (created by microscopic synthetic setae) to cling to walls. Less well-known is the work on an electrically-controllable alternative developed by researchers at SRI International (formerly called Stanford Research Institute) called "electroadhesion". Impressively, the electroadhesive can support 0.2 to 1.4 N per square centimeter, requiring a mere 20 micro-Watts per Newton. This means that a square meter of electroadhesive could hold at least 200kg (440 lbs) while only consuming 40 milli-Watts, and could turn on and off at the flick of a switch! Read on for pictures, videos, and discussion.

So too your Dyson sphere. It maintains a charge on its surface adequate to produce intermolecular forces which replicate gravity, pulling down its inhabitants and the accoutrements of their world.

Willk
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  • This is awesome. I was thinking VDW forces could be a solution but didn't think it was strong enough. Since this would be the only noticeable force, it would be far more effective, as the only other force is the negligible pull from the sun. – ZoneWolf Aug 06 '18 at 06:09
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Lots of ringworlds

You have a bunch of ringworlds at different angles until it covers the entire star. How are the ringworlds built? That is a question for you to answer.

I linked an interesting video on Dyson Spheres that I highly recommend you watch. (I got the ringworlds response from the https://www.youtube.com/watch?v=HlmKejRSVd8&vl=en

0something0
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How far away is your Dyson Sphere from the sun? Three million kilometers away from the surface of the sun, you'd be seeing about a g of gravity on the surface of your Dyson Sphere.

$$ F = G \times \left( \frac{Mm}{r^2} \right) $$

$$ F = 6.674 \times 10^{-11} \times \frac{1.9891 \times 10^{30} ~\text{kg}}{(695 \times 10^6 + 3 \times 10^9)^2} = 9.7 ~\text{m/s}^2 $$

Since you're able to build a Dyson Sphere, you should be able to store the sun's energy with a high degree of efficiency, making heat problems moot. Just make your Dyson Sphere smaller.

Ben
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  • 3 million km from the sun you would be incinerated instantly. Thats less than a tenth of mercury's orbital height. – ZoneWolf Aug 03 '18 at 11:04
  • please note that this would be gravity pointing Towards the sun rather than towards the inner surface of the Dyson sphere. this solution would require the population to live on the outer surface of the sphere (though is still completely valid). – Ummdustry Aug 03 '18 at 15:58