Questions tagged [gravity]

For questions about the universal accelerative force between all objects.

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72
votes
14answers
9k views

How to harness Jupiter's gravitational energy?

I am currently orbiting Jupiter, the rent is pretty cheap and the view is magnificent. However, my former electricity provider refuses to connect me to earth's grid for petty reasons like "are you ...
62
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15answers
39k views

Would the human body support living on planets with a greater gravity than Earth?

I once read a novel about a prison-planet which was chosen to make the prisoners suffer. One of the different "tortures" was a gravity three times higher than that on Earth. Would the human body ...
56
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11answers
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How would people conceivably escape a planet too large for chemical rockets?

I was reading this article from NASA about chemical rockets and they argue that, with a planet 50% larger than the Earth (assuming similar density, about 1.5G surface gravity), it would be impossible ...
45
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5answers
7k views

What are the safety margins for destroying a planet from space?

My empire's flagship, the Persecutor class UJBHE1 Abhorrent, rides into the home system of my greatest enemy, Baron Obsequious, levels its Death Ray2 at his beloved home, and pulls the trigger.3 ...
42
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7answers
7k views

Could a cave-in or avalanche in low gravity be dangerous?

I have a character on the surface of Enceladus, one of the moons of Saturn. It has an icy surface on top of what is believed to be a liquid ocean. There is no atmosphere, though near its south polar ...
41
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10answers
9k views

Is there a working law of gravity in 2D?

I am constructing a two dimensional world, but ran into a problem with one of the fundamental forces, gravity. I first tried to see what would happen if I just used the normal law of gravity, $\frac{...
36
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9answers
12k views

What are the effects of slicing the Earth in half with a particle beam?

Scenario: An exact copy of our world is sliced in half by a particle beam. The beam has a diameter of 40 meters and moves at a speed of 0.999c. The beam slices the earth from top to bottom in 600 ...
35
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11answers
11k views

Why are low gravity humans depicted as TALL?

I totally get why humans who have colonised a low gravity environment (Mars or an asteroid, for instance) are skinny. Muscles doing less work, square cube law, force output of a muscle proportional to ...
33
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10answers
12k views

How many pillows would you need to survive a fall from a church tower?

The praised Dutch book "Koning van Katoren" features an 18 year old who wants to become king of his country of Katoren, which had been under the regency of half a dozen evil ministers for his whole ...
33
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16answers
12k views

Can airborne floating/flying islands be scientifically possible?

I'm sure that this has been asked before, but I need floating islands for a fiction story I'm writing. It takes place 5000 years after a catastrophic event (on a vaguely earth-like planet populated ...
33
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5answers
6k views

What would the problems with / consequences of a torus shaped planet be?

Take a torus planet: It has the structure of a normal planet (ours): The diagram is not to scale. Assume similar proportions of Crust:Mantle:Cores as the Earth. Is has a similar volume (close to 1.1 ...
32
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2answers
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Gravity on a Minecraftian world?

I'm curious what the gravity would be like on an infinite area flat world. The plane of the world would have some finite depth but be infinite in all cardinal directions. This is, in effect, a ...
31
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4answers
7k views

A planet rotating twice per second; what mass is needed to hold it together, and how oblate would it be?

I want to create a planet that has a frequency of two rotations per second, thus making a "Planet without Night". The planet will be like a flattened disc, due to inertia causing the planet to be an ...
30
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4answers
3k views

Lopsided artificial gravity

I'm trying to come up with a the most economical design for artificial gravity. The simplest design for a space ship is to have a spinning ring structure around a central body. People living in the ...
29
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7answers
8k views

5km artificial planet, with same gravity as on Earth

So, the idea in a story is that in far far future there’s a trend that rich people, they are able to buy themselves planets. Tiny little planets with sizes 4-6 km (3-4 miles) in diameter. The company ...
28
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6answers
5k views

What would birds look like if they used buoyancy to fight gravity?

What would birds look like if they did not have to fight gravity to fly? The question comes from the premise put forward by some that gravity is not real and that what holds us down is pressure ...
28
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4answers
4k views

How likely are Coriolis-effect-based quirks to develop in starship crew members?

This one's more sociological, and it seems like a shoe-in to me, but sociology was never my strength. Given how pronounced the Coriolis effect of a smaller Von Braun wheel would be, does it seem ...
28
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4answers
4k views

How much gravity should I have on my spaceship?

The starship 'Exciting Undertaking' has set off on a brand new five and a bit year expedition to explore the galaxy. To make such a starship possible, an artificial gravity generator had to be ...
27
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5answers
7k views

Could you fall off a planet if it was being accelerated by engines?

Some background In the movie The Wandering Earth, the rotation of Earth is slowed to a stop, and then 10000 engines are strapped to one side of the planet and used to accelerate it out of the solar ...
27
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14answers
7k views

A planet with changing gravity?

A planet with changing gravity On earth gravity stays constant (besides negligible fluctuations), but it may be possible to change that. What kind of geology, natural satellite, or other anomaly ...
25
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4answers
5k views

What minimal radius is needed for rotation to simulate gravitation without adverse effects on humans?

A quite common idea to provide "gravitation" in space stations is to make them rotate, so the centrifugal force gives an effective gravitation. A possible design is a ring-shaped space station. Now ...
24
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7answers
40k views

How would the human body develop under a different gravity?

What would be the effects of high or low gravity on human body development? How would the human body develop under a different gravity? Many science fiction stories explore the idea that people from ...
23
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8answers
4k views

What could cause an entire planet of humans to become aphasic?

I'm working on a story in which there is some sort of planetary erosion of language. Humans lose the ability to communicate verbally (orally and written). They can remember having language, can even ...
23
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7answers
7k views

How big can a moon be where you can physically jump out of its orbit, to its planet?

So, imagine a team of space marines, fighting some sort of space bug zombies on a planet's moon. Things are going pretty bad for them, and the last surviving protagonists are running for their lives. ...
23
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9answers
5k views

Gravity magic - How does it work?

This question graduated from the Sandbox for Proposed Questions Gravity magic - How does it work? (What physical law can magic manipulate in order to affect gravity?) In my world everyone is ...
22
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16answers
9k views

How to put a lake on the ceiling?

Another user's answer to a recent question, specifically the way it was worded, gave me a vision I cannot shake. Our intrepid adventurer, Joe A. Venture, is making his way through a subterranean ...
22
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8answers
5k views

Extremely small planet to live on

In the mobile game "The Path To Luma", the main hero travels to very tiny planets. Let's not think about where is the sun and how we leap through such small planets. What I want to ask is, if there is ...
22
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5answers
4k views

What happens if everything stops?

Suppose, through some fantastical mechanism, all macroscopic (i.e. reasonably massive) objects in the universe were instantly made at rest. In other words, the relative velocity between every two of ...
21
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13answers
11k views

1 Light Year Diameter Planet

Suppose a species has limitless resources and the ability to construct megastructures of an astronomical scale. Would it be possible, given antigravitational technology (hypothetical), to create a ...
21
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14answers
5k views

How would houses change if we could walk on the walls?

My character has stumbled upon another planet with life, and they are able to walk on walls and ceiling, completely ignoring regular gravity (by magic, science, whatever, it doesn't matter all that ...
21
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5answers
25k views

What factors determine a planet's gravity?

In Science Fiction we often see the protagonists exploring all sorts of strange new worlds with no apparent discomfort to the variations in gravity. What factors determine how strong the gravity will ...
20
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8answers
10k views

How could a smaller planet than Earth have a higher gravity?

I want to build a planet (or satellite) that: is smaller than Earth, has a thicker atmosphere than Earth but breathable, has neither intense volcanism, nor any extreme condition of that sort that ...
19
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19answers
7k views

Why limit to revolvers?

I am thinking about a game where people will shoot out in space, with different features. However, an integral part of the game is no spraying/spamming bullets. I don't want to have it in a fantasy ...
19
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7answers
6k views

A continuous water "planet" ring around a star

It is impossible to have a continuous mostly liquid water ring around a star? Probably such a configuration would be unstable under normal planetary forming condition. I am looking for a good ...
19
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9answers
5k views

What is the largest 'hollow' space structure that can be created?

After reading the following question about anti-gravity, I wondered what the largest hollow structure you can make in space is. None of the questions about hollow earth seem to answer this. To put it ...
19
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7answers
6k views

How does gravity affect evolution of life?

I have two "new" planet earths -- we'll call them Light Earth (LE) and Heavy Earth (HE). These planets are generally the same as our Earth in terms of land masses, oceans, the moon and sun and other ...
19
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4answers
5k views

How small could an Earth-like planet be while still realistically being able to sustain human life?

I'm thinking a planet orbiting a nearby star colonized by human settlers sometime in the not near, but not too distant future. How small could a planet be while still standing in as a relatively ...
19
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3answers
554 views

Is there software to help me model tides?

I have a planet orbiting a roughly Sun-like star, accompanied by a moon that's a bit more massive than our own Moon. The surface is about two-thirds water and one-third land, with most of the land in ...
18
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10answers
8k views

In a world with escape velocity greater than the speed of light, would a civilization be able to reach space?

Htrae is a planet with an abnormally strong gravity. In Htrae, the escape velocity is greater than the speed of light. Suppose a civilization like humans (call them snamuhs) evolves, with the unique ...
18
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6answers
5k views

How noticeable would it be if gravity decreased to be around 90%? [closed]

I am wondering how it would feel if gravity suddenly got reduced to be around 90% of what it was. Like if a person was not paying attention or was asleep, would they notice?
18
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9answers
3k views

Gravity alteration as extermination tool viable?

An alien race was rubbed the wrong way by humans being humans and decided that humankind has to go. However, unlike many other science fiction stories, they do not intend to give the humans even a ...
18
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9answers
6k views

Is a moon inside a hollow Earth possible?

The Hollow Earth theory is/was a pseudoscientific idea that our world is actually on the inside of a large sphere. The "sky" points inward towards the center, where the "Sun" (a light source) is, ...
18
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6answers
3k views

Making the Enterprise Fly

No, not that one. This one. I want to see the USS Enterprise fly, but I'm curious how it would be accomplished in any realistic fashion. Now, the world I'm building that needs a flying Enterprise ...
18
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7answers
3k views

How would long-term exposure to artificial gravity (as generated by a Stanford torus) affect human evolution?

A space colony that resembles the design of a Stanford torus generates artificial gravity by centripetal force. Discussions about benefits of such fake gravity can be easily found: no more constant ...
18
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1answer
4k views

What would the Universe be like if gravity was slightly stronger?

As the title says, what would the universe be like if the gravitational force was 0.1% stronger but the other forces (strong and weak nuclear forces, electromagnetic force) stayed the same? Would the ...
17
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8answers
4k views

Would trams be workable on a low-gravity world?

After reading this thread from a bit under a year and a half ago about the most cost-effective means of travel on Mars, where one of the answers mentions rail as the best option, I started wondering: ...
17
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9answers
3k views

Physics Plus: Artifical Gravity in Space

This is the next piece in my question-series, you guys have been absolutely awesome in your answers to the first question: How to solve the old 'gun on a spaceship' problem? In this series, I try to ...
17
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6answers
4k views

Doomsday-clock for my fantasy planet

I want the surface of my fantasy planet to be made hostile every few thousand years for long enough to make every species go extinct that breeds on land. The easiest explanation seems to be other ...
17
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5answers
3k views

Higher Gravity vs Higher Air Density

Planets that are larger and have higher gravity tend to have thicker atmospheres, since it is easier to hold onto gases. Higher air pressure leads to a higher air density, and therefore, a greater ...
17
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4answers
3k views

What would happen if the black hole at the center of a galaxy was removed?

Say you have a galaxy, possibly ours, with a central black hole. In an instant the black hole falls through a plot hole and vanishes. What happens to the rest of the galaxy? Does everything keep on ...

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