# Questions tagged [megastructures]

For questions about extremely large artificial structures, including buildings.

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### Calculating Living Area on a Concentric Shellworld

I'm not sure if I should be asking this here on on the Maths Stack Exchange, because this is a sort of mathematics problem but here goes: A civilization lives on multiple concentric shellworlds, each ...
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### How many miles/km of tunnels would be required to replace all airports in the world

Assume that we wanted to replace all air travel with underground, high speed tunnels like Hyperloop. How many miles/km of tunnels would be required? For example, according to wikipedia there are 1200 ...
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### How would humans on Earth detect a Shkadov thruster on other side of the Milky Way Galaxy?

Apologies if the title is confusing - I've been trying to figure out how to word it for a while now. Essentially I am writing a (relatively) hard science-fiction story set in the present/very near ...
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### How would a dyson swarm actually work? -Orbits

SO HOW WOULD A DYSON SWARM'S ORBIT LOOK LIKE? we are all familiar with the concept of a dyson swarm, a series of orbital stations' reflective satellites that serve to collect the energy given off by ...
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### How differently would Earth's wind and ocean currents look if it were a shellworld the size of Neptune?

Earth is a quaint little green-and-blue marble 7,917.5 miles wide and 196,941,385 square miles in area. It's just small enough to create a busy, dynamic network of wind and ocean currents. These two ...
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### Why would aliens fill a quarantine space with inert gas?

While experimenting on a Mysterious Alien Artefact at a Super Secret Research Facility, the protagonists accidentally activate what turns out to be a homing beacon, and teleport everything in a sphere ...
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### What powers a shellworld?

There are many futuristic megastructures that get called shellworlds. In this case, I am referring to the concept of a hollow sphere which encloses a gas-giant or other massive planet; suspended at ...
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### Motivations for creating "brainstar" bioplanets [closed]

I define a "bioplanet" as any single organism that completely covers the surface of a planet. In my scenario, humans pass Kardashev Type I status and build a Matrioshka brain around the core ...
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### Feasibility of a 5000km tall orbital tower using active support

Note: I'm working on a far future sci-fi setting for a novel series which aims to blend elements of both "soft" and "hard" science fiction concepts. I'm aiming for the series to be ...
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### Suitability of White Dwarf stars for supporting a Matrioshka Brain?

Note: I'm working on a far future sci-fi setting for a novel series which aims to blend elements of both "soft" and "hard" science fiction concepts. I'm aiming for the series to be ...
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### How do I explain volcanos and plate tectonics on a hollow world?

The world my setting takes place on is an artificial shell world set into the FAR future (somewhere between several hundred million and nearly a billion years) after a cataclysmic event wiped out it's ...
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### Would it be possible to build a powerless holographic projector?

For one of my (many) science-fiction projects, I am designing immense rotating space-habitats. These titanic structures, (similar to Bishop rings; see here https://en.wikipedia.org/wiki/Bishop_Ring_(...
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### Could all of human population fit in China, India, and Mongolia?

I have a scenario where Aliens must escape their Star system because a star 5 light years away from them is going nova soon. They find humanity and learn all about them in a few years - our whole ...
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### Orbital Mechanics of a shell world

I've created a Neptune sized shell world with properties that I find are not typical of other shell worlds. Its gravity does not come from a gas giant or a black it was constructed around, but from ...
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### What to do so the sun (light source) appears to be following a daily cycle on a McKendree cylinder?

In my setting, a McKendree cylinder (a rotating habitat so large it holds its own atmosphere) is orbiting the sun, with the top of the cylinder pointing at the sun. How do we make the sun appear to ...
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### dyson shell world, how do you create artificial gravity so people can stand on the inside of the shell?

one of the ideas I had is to make the Dyson shell a series of bands(made from impossible material with extreme tensile strength) and then spin these bands at different speeds, with the "land ...
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### Minimising the environmental effects of my dyson brain

Many centuries from now, a race of advanced AI who now rule humanity, but who are aware that they themselves are leaderless, begin the construction of a huge dyson-sphere fuelled computer brain to ...
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### What is the minimum size for an “open” space habitat?

In my science-fiction universe, rotating space habitats are widespread, and range a great deal in size. However, all fit into one of into 2 classes: “closed” habitats, which are too small to retain an ...
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### How to keep a giant shell around venus rotating normally

So, let’s face it, terraforming Venus is a bust. There’s simply no good way to do it without speeding up its rotation, which demands huge quantiles of energy. Any civilisation that could produce this ...
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### Creating a second earth: How to make a continent?

So, to cut a long story short, a group of people are attempting to turn an earth-sized exoplanet into a new earth; that is, a planet artificially made indistinguishable from old earth. This planet has ...
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### Methods to move supermassive black holes?

There is an advanced civilization that need to move the supermassive blackholes (SMBH) of their galaxies. I have seen some similar questions on here but the ones I have read are for moving much ...
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### What happens at the hub/core of a rotating space station?

My setting is a standard rotating ring space station. I want some action to happen in the core, specifically for the hero to take down a "hypercom" system that is housed there. I'm trying to ...
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1 vote
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### What compounds could be used to dye a gas giant the colour of a rainbow?

So, we have an incredibly advanced clarkean civilisation who, having achieved godlike technology, have taken to transforming whole planets and solar systems into works of art. One of these is Rainbow, ...
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### Effects of Superconducting Rings to create a magnetic field around a planet

Continuing along my oft-contineud series of questions relating to terraforming, I return to an idea of giving Mars a magnetic field which I had hitherto dismissed. The idea is that a huge ...
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### Best materials to build a worldhouse roof

In an imagined sci-fi universe where immense space habitats and constructs are common (however, nothing reaching nearly the size of a Niven Ring) one of the many forms are worldhouses: planets ...
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### How would a basic space station of this design work?

For my book, I need a simple, basic layout to work with for a space station. I am using a typical spinning cylindrical design, a core in the center, a number of levels surrounding the core (in my case ...
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### Building materials for a palace or castle on a volcanic island?

I have a magical setting I am working on in my world that is based on a large volcanic island that has been created by a sunken, fantastically large caldera. Up to this point, my story has centered ...
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### How Can We Illuminate a Bishop Ring?

A Bishop ring is a space habitat, in my project about 100 km long and with huge walls 10 km high to keep the atmosphere in. The ring rotates about once every 20 minutes to simulate 1 G, and is built ...
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### How could a 1 TW power plant be built?

As of 2021, global electrical production was about 7 TW. And the largest single power plant is the Three Gorges Dam at a capacity of 22.5 GW. My hero needs a single power plant with 50 times more ...
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### Mt. Everest Hyperloop- Reborn

In my previous question, I was discussing about the possibility of using a mass-driver on Mt. Everest, to propel payloads to space, and reduce the amount of fuel needed (RIP bulky rockets). A diagram ...
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### How can I hit a planet with an energy beam from ten lightyears away?

My interstellar empire is powered by a quasar. Or at least it will be once I finish my scheme. See that cloud of glowing dust? That's called the quasar's accretion disc. When stuff falls into the ...
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### What are the most compact batteries to store energy from my quazar power plant?

In my previous question, I dealt with the possibility of harvesting the energy of the accretion disk and jets of a quasar Milky Way, by the use of multiple mirrors and panels that are orbiting around ...
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### How much energy would a Type III civilisation get from a Quasar Milky Way per day?

Let's say, (in the far future), that humans have become really advanced beings and are at the verge of becoming a Type III civilisation. Now, they need a gargantuan energy source for various purposes, ...
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### How long would it take an average person to climb an one-hundred and twenty billion feet tower? [closed]

I saw a recap of a film called Fall released this year. It is about 2 girls stuck on the 4th highest structure(supposedly) in the USA. It got me to thinking about very tall things and climbing them. I ...
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### Saturnian Zeppelin Cities: can I use Aerographene coated with Titanium as the hull material to prevent getting crushed by atmospheric forces?

(After receiving countless suggestions from users like Sojourner, Wilik, and EngrStudent, I have come up with a solution to a cloud city on Saturn.) So, I ran a few calculations on Air Density ...
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### Would an Alderson Disk be possible around a White Dwarf Star?

I have seen the ideas of Alderson Disks around Sun-Like Stars. It would be utterly massive to say the least. Would an Alderson Disk be more 'possible' around a White Dwarf Star, how large would it be ...
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### Gas behavior in geosynchronous orbit

I am trying my hand at worldbuilding a sci-fi setting, specifically a partial/broken ringworld. Specifically I have trouble wrapping my head around gases. I have 3 scenarios, solutions of which will ...
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### Can you build convection currents out of hollow air?

Recently, I found this image by the Redditor "Keeperofbeesandtruth": He made it free to use, as he doesn't intend on being serious about his own project. So here's my plan: Keep the ...
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### Would a space elevator necessarily need to be situated on the equator?

The simplest kind of space elevator would be a large mass somewhat beyond geosynchronous orbit tethered to earths surface such that the tether is always under tension from centrifugal force ...
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### Structural integrity of massive space vessels and mobile megastructures (>1.5km)

I'm working on a worldbuilding project, and so far I've been putting scrutiny into my larger vessel designs, notably a 1.7km long spaceliner capable of landing at specific launch facilities. Someone ...
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### Ballistic properties of unobtainium

A Banks Orbital requires some form of unobtainium, with tensile strength much greater than any known substance. I'm trying to figure out how that substance would stand up to impacts and explosions. To ...
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### Why would a bio-mechanical Dyson sphere need to abduct and subsume an entire sentient species every 30-to-50 years?

THE SPHERE Up in space, there is this massive Dyson sphere, with a radius only slightly smaller than the earth's moon. It's made up of a creepy fusion of organic matter and mechanical machinery and is ...
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I started thinking about Alderson disks. They are usually portrayed with large uninhabitable sections on either side of the habitable zone. Why not just build the habitable zone, and save materials? (...
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### How does ocean productivity vary with depth?

I'm trying to figure out the optimal sea depth on an artificial world (a Banks Orbital as it happens, though I think this would also be an important parameter for many other kinds of megastructure). ...
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### Depth of seas on a Banks Orbital

If one is building a Banks Orbital or other megastructure with a very large habitable surface area, it is not necessarily given that much of the area would consist of seas, but there are several ...
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### Visibility of a Dyson swarm "creature" from its orbiting planet

An alien species has built Dyson swarms around stars which have orbiting planets with primitive life on them. The section of the star which is facing the planet with life is left uncovered to let the ...
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### How large would this Laboratory ship have to be?

The ship in question is a biological lab that is out at sea for isolation and for easy disposal if something goes wrong. The main focus on this ship is a new cell bonding agent that has allowed them ...
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### How big does a world have to be to not have a sunset?

Normally we watch the sun descend, it's dimmed a bit by the atmosphere before dropping below the horizon. What I'm interested in is how big it would have to be so the atmospheric dimming is sufficient ...
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### Method of expanding a city in toxic environment

A city on an alien desert needs to expand, here is the method I feel should be cost-effective and cheap. Use the image below for reference. A square area is mapped out and leveled off for the ...
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