# Questions tagged [gravity]

For questions about the universal accelerative force between all objects.

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### What would life be like in a universe with gravity that increases with distance?

We live in a universe where gravity is determined by the inverse squared of the distance between the two objects. Inverse gravity has already been explored here. But what if gravity grew stronger with ...
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### Crafting a Water Cycle for a Cube World with State-dependant Gravity

So I have a cube world with the standard 6 sides, with a top and bottom that do not change. We can ignore any rotation of the other side-sides for the sake of this question. I am trying to come up ...
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### Can a cube-shaped(ish) world have uniform(ish) gravity when composed of ideal materials, including antimass?

I'm trying to design a cube world while sticking somewhat closeish to real physics, but am not entirely sure about the physics involved with objects of non-uniform density, specifically as relates to ...
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### How do these trees not collapse? [closed]

I'm currently building a planet, an ammonia world with an average temperature of 225ºK and has a mass of 2 earth masses and a radius of 1.25 earth radii. The average pressure at sea level is 4 ...
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### How much mass could be added around the Earth before the Earth's orbit around the sun changed?

In the not too distant future Earth will enter its golden age of industrialization and construction. Pulling raw materials from other planets (not from Earth), humans begin building mega structures ...
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### Climate on a Moon orbiting a primary in the habitable zone of a sunlike star

I created the following system (including a simulation in universe sandbox which seems stable): Sun-like G-type star with same mass, density, radiation profile, diameter and luminosity as the Sun. ...
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### How do Hill spheres work for binary planets?

A small moon is able to maintain a stable orbit around a planet at just under half the radius of the planet's Hill sphere. Most of Jupiter's moons are in this configuration, possibly made more stable ...
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### Binary Star System Physics

I am envisioning a planet that has two orbiting stars: a small yellow-white F class and a larger orange K class star. The stars were once closer and created a more tumultous tectonic history but since ...
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### Gravity changes in relation to different sizes of celestial objects

The Problem I changed the circumference of some of my world's celestial objects. How can I calculate the object's new gravity? The density of the objects is still the same as it would originally be - ...
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### Roughly how big could the tidal range be on a human habitable Earth analogue world?

The Gravitational tidal forces can be supplied by any orbiting moon(s)/twin planet(s) of any mass and any orbital radius, inclination or orbital radius, but the system must be stable for at least 10,...
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### Would things engineered to work on earth work ok in 1.25 times earth gravity? [closed]

A while ago I asked this question about if a planet 1/5th larger than earth could remain earth like. The top answers all seemed to agree that while the planet could be that much larger and still only ...
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### How close to a star could a dense asteroid belt reasonably form?

I would like to have an asteroid belt "close" to a star. I want it to contain "large" asteroids. Is this plausible? I believe the location of our real life asteroid belt is ...
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### How to create a network of stable traversable wormholes, how those WH behave when interacting with gravity and vessels, and how they look [closed]

first time poster on the world building site, and I have several questions about wormholes and how they work. I've been reading through the other questions tagged "wormholes" and researching ...
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### Industrial applications of high gravity

I've just finished reading Mission of Gravity by Hal Clement, a reasonably hard-scifi novella set on a planet with exceptionally high gravity: 700g at the poles, offset by very rapid rotation to 3g at ...
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### Characteristics of a moon harboring huge flying creatures?

I’ve been thinking for a while about an extraterrestrial species I had in mind that more or less resemble very large four-winged four-legged birds, and in the name of ensuring I don’t handwave an ...
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### How would humans evolve in this star system?

Say that a large amount of humans settled in this system and have been living there for a few tens of thousands of years. The system is a binary system with two stars, a sun-like yellow dwarf and a ...
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### A small planet with earthlike gravity

Is it possible to create an Earthlike planet, that is smaller than the Earth , like for example the size of Mars, by altering the core composition like for example making it: Iron (Piron ): 75.6% ...
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1 vote
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### Earth sized object with negative mass superimposed 1:1 on Earth. What happens to its orbit?

Assume the superpower to instantly conjure a 1:1 Earth sized object with negative mass exactly equivalent to earth size and mass but negative, superimposed upon Earth. Also, please keep in mind ...
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### How viable are Airborne Aircraft Carriers on my alien world?

I have made a world that is a massive flat plane, with the surface gravity and atmospheric pressure of Titan, but a composition similar to Earth. There is one race, humans. Humans have a problem ...
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### What would the effects of drinking reverse gravity water be? [closed]

If you drank a special type of water that falls in the opposite direction of gravity, what would happen? Since you can drink water while upside-down, it might just be the same, but I wanted to make ...
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### Pulsed Acceleration Gravity

Let's say I have a spaceship under construction with a habitation module and I want a reasonably compact means of mimicking the compressive effects of gravity on the body I have two candidate ideas ...
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### Radioactive planet wrecks civilisations every 5 millennia- How stable will it be?

Backstory Okay, so for now, let's pretend the creatures on this planet are just the same as those on Earth. Humans, cattle, pets etc, are just the same, cause I haven't yet thought up the biological ...
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### Using gravity and the Higgs Field as an inertial damper [closed]

Einstein allegedly proposed a thought experiment to back up his theories of relativity, about forces due to acceleration and forces due to gravity (even though the idea had been around since Newton) ...
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### Would Artificial Gravity With Short Range Be Possible?

Assuming a spaceship with artificial gravity was possible, would it be possible for it to have an extremely short range, like a few feet. So you'd be able to have a ship with 1g but not have it ...
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### requirements for spatial manipulation [closed]

In my story, I have a power system that allows humans to control certain universal forces. For example, chronomasters could control time and electromancers could control electromagnetism. Some spatial ...
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### What is the lowest reasonable density for a Super Earth with earthlike living conditions?

A large planet roughly 3-4 times the mass of Earth. Trying to keep Gravity between 0.75G-1.25G for Earth-like Conditions. I've looked into certain materials such as Silicon Carbide, which is ...
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### How can I avoid the runaway greenhouse effect on a planet with 2x Earth masses and a dense thick atmosphere?

I've been working on a spec bio project with a planet which is 2x Earth masses with a dense atmosphere. However, I have one big issue : how do I avoid making a runaway greenhouse effect? Like the ...
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### Could a planet 2 times the mass of earth have floating organisms in its skies

Can a planet 2 times the mass of earth have floating animals in its skys? I watched the netflix documentary series ailen world's and one of the exoplanets atlas was high gravity but was very dense so ...
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### Finding a stable atmosphere for a different gravity

I am trying to find what would be a stable atmosphere for a planet, using this https://docs.google.com/spreadsheets/d/1cW7BIWlBUscqS9MVqs5gSbPH0OGzyE-j2cz6ADBSVzE/edit#gid=0 (you have to make a copy ...
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### What would a planet where giant creatures live be like? (gravity, weather, etc.)

I am thinking about a planet on which gorilla-like people live in. Gorilla-shaped, walking on their knuckles, but with the capability of complex speech and a slightly more humanoid face (possessing a ...
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### Is it possible to store the gravitational energy between planets somewhere in space? [closed]

Say I have a space station operating between Mars and earth. Can it somehow steal energy from Mars- Earth Earth - Sun Sun - Mars Combinations of gravitational pulls? Would it distort he orbits?
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### Can a tidally locked planet with two counter-orbit moons exist for at least 100,000 years?

I believe it is true (correct me if I'm wrong) that a planet with a significant moon such as ours cannot be tidally locked. The orbit of the moon would continue the rotation of the planet and must, ...
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### High Gravity Giant Shell

I am designing a genus of eusocial, high-temperature, extraterrestrials from the planet 61 Virginis b. They are based on tungsten chloride and use sodium chloride as a solvent. This species has ...
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### Decaying Planets

Assume there is this planet with only one type of life; a planet-wide mat of microscopic lithotrophs. These creatures eat through the surface of the planet over time, converting the surface into gas. ...
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### Is there a reason for Rocket-style vertical takeoff craft when you don't need to bring reaction mass?

Reactionless Drives? I have a sci-fi setting that takes place very far in the future. I like to think it tends toward the harder side of sci-fi, so I'm trying to minimize the number of Clarketechs (...
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### How fast does this planet have to rotate to have gravity thrice as strong at the poles?

For those of you who have read mission of gravity, or researched Saturn’s equatorial bulge, you will know that the faster a planet rotates, the greater the “flattening” effect it’s rotation has. This ...
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### World built inside a gigantic drainage pipe

I'm doing a Pratchett style fantasy book, and the setting - the Downspout - is built in a downspout of an astronomically sized gutter drain pipe. We're assuming an impossibly large structure housing ...
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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 would tires look like on a super-Earth with 2.5 G surface gravity?

A super-Earth has 2.5 G of surface gravity, as opposed to the Earth's 1 G of surface gravity. Some folks on it drive wheeled vehicles, and the wheels on said vehicles have tires on them. These tires ...
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### Millitary applications of a gravity drive [closed]

Let's say gravity drives exist. This is a device that can power a spaceship by creating an artificial gravity well some distance in front of the spaceship that the spaceship perpetually falls into, ...
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### Would it be possible to alter the gravitational field of a planet to one more suitable for human habitation?

I know low gravity can have negative effects on humans, and I would guess high gravity would also have negative effects. So would it be possible to increase or decrease a plant’s gravity to better ...
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### Is there a way for a Super-Earth have Earth-like Gravity?

I have a planet about 2 Earth Radii large, and even at a lighter Density this puts it squarely in the 10 Earth Mass Range and about 2.5g. It's about 90% ocean, has a thick atmosphere, and near ...
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### Would these solar systems be stable?

I have two solar systems in my world that I'm not sure would be stable. I'm not concerned about whether they could evolve naturally (they didn't), just whether they would be stable if set running. The ...
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### Turning possible a gigantic rock in the sky (sci-fi and magic)

Ok, we have magic to solve all my problems but I want to find if I can solve this "the most cientific possible". I have a world that turns out to be the earth but in a post-apocalyptic ...
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### If humans colonized a world with .75 earth gravity, would they evolve to be thinner and taller?

Humans are stranded on a world with .75 Earth gravity. How would that affect their physical evolution? Specifically, would they be taller, thinner, and have less bone mass?
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### Any way of having a breathable atmosphere with zero gravity in free space?(and universal directionality?)

Inspiration This is heavily inspired by sunless skies in that sunless skies' world allows for the use of steam engines as space ship- equivalent (using steam jets as thrusters, while still able to ...
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### Question on gravity and its relation to weight and force

I'm working on a character for a story that has the ability to somewhat play around with gravitational forces, mainly weight reduction stuff but I'm sure there's other applications. Practically this ...
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### Could you use the gravity of an extremely close gas giant to assist in leaving a planet

Scenario: A gas giant knocked off orbit is projected to make an extremely close approach to our planet. Close enough to cause miles high tides, continent wide earthquakes, and send our planet on an ...
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### Could a planet have 1/2 the Earth’s mass but 1 g surface gravity?

So, we have a captured planet/moon orbiting a gas giant in the habitable zone. It is akin to prehistoric Mars, its geological activity having been maintained by constant tidal flexing from the gas ...
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