Questions tagged [gravity]

For questions about the universal accelerative force between all objects.

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33
votes
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 ...
62
votes
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 ...
32
votes
2answers
3k views

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 ...
1
vote
2answers
1k views

Gravity of a Super-Earth

So, I created a planet that has a civilization that is beyond advanced. The planet's radius is 10x the radius of Earth, and is has the same density as Earth. What issues would I have with the gravity?...
8
votes
2answers
653 views

Surviving the world of zombie mosquitoes

Some Details Suppose an Earth-like world with the following changes: Atmosphere: 67% nitrogen, 31% oxygen, 2% other Average surface temperature: 16.7° C (62° F) Day/night cycle: 20 hours Gravity: 0....
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 ...
24
votes
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 ...
25
votes
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 ...
9
votes
6answers
1k views

How would artificial gravity be achieved in space?

I am wondering, what mechanism would be needed to generate gravity on a space ship in interstellar space, like we see it on Star Trek or Star Wars? What is the most realistic hypothetical way what ...
11
votes
5answers
1k views

How would an earth-like planet with a habitable moon work and how to get there?

I have a planet approximately 3.5 times the mass of the Earth. I have a moon orbiting that planet that has to be habitable as well, because my story will take place on the first expedition to this ...
29
votes
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 ...
18
votes
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 ...
19
votes
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 ...
17
votes
1answer
837 views

As we increase the size and mass of a world, at what point does it become impossible for a rocket to achieve an orbit or escape velocity?

Many authors describe worlds with higher gravity than our own, from whence super-muscular aliens originate. However, as we increased the size, mass and surface gravity of a world; there would be ...
18
votes
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, ...
12
votes
5answers
5k views

Could there be a planet bigger than Earth, but with less gravity?

Is it possible to have a planet that is both bigger than Earth and weaker in terms of gravity? I've got an idea about it being less dense, but I don't know what to do about its magnetic field. I need ...
27
votes
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 ...
12
votes
5answers
486 views

Which astronomical or cosmological event would explain periodical low-grav-effect on earth-like planet?

Imagine an earth-like planet on which gravity is reduced by 20%-30% every 15 months. The low-grav-effect should start slowly, reaching its peak/bottom of round about 0.7 g after 6 weeks and should ...
11
votes
8answers
1k views

Smallest possible habitable planet? (also taking density into account)

I have seen a few similar questions but none seem to take the density of a planet into account. I'm creating a planet on which several small civilisations develop. The planet needs to have a few ...
5
votes
6answers
1k views

A world with 1/3rd gravity but 1/2 atmospheric pressure. Would it be easier to fly?

Let's say on an alien planet called Thindor, the surface gravity is 3.27 m/s2 (which is 1/3rd of Earth's). But the atmospheric pressure is only 50 kPa (which is 1/2 of Earth's). Assume the same 20/80 ...
16
votes
3answers
3k views

What would happen to the Earth if Gravity disappeared?

This is a multi-tiered question. I have seen these larger questions before, but if I need to separate them out into their own questions let me know. In my story I have a machine that can manipulate ...
8
votes
3answers
2k views

When does gravity become too much for humanoids?

Supposing you took Earth or a planet like it and doubled its mass, the gravity would obviously increase in whatever proportion to that. As a result, humans as we know them would be ... thicker, (I ...
4
votes
3answers
171 views

Would a small low gravity moon be able to harbor complex life?

I was thinking of creating a moon that has low gravity which allows trees to grow extremely tall and would make for an interesting ecosystem. My question is would a relatively small moon with less ...
14
votes
3answers
2k views

Do the moons of Mars have enough gravity to colonize?

Context NASA commissioned some awesome, vintage-style prints a while back advertising the colonization of Mars. Three of them stood out to me because they depicted colonization of the moons of Mars - ...
11
votes
4answers
1k views

Air transport breaks down

How much would the gravitational force (on earth) have to increase to make air-travel impractical (not impossible as escape by space flight to other planets would be a nice option). But to a point ...
8
votes
2answers
240 views

Tolerable range of surface gravities for interplanetary colonists?

Human physiology is adapted for life at 1G, but planets colonised by future humans will likely have different surface gravities. What is the range of values for surface gravity that humans can ...
6
votes
4answers
9k views

Circular space station - what's the rotational speed to achieve earth-like gravity?

Imagine there is a space station shaped like a cylinder. The cylinder spins on its axis, in order to create artificial gravity through centripetal force. My question: How fast would the space ...
16
votes
2answers
2k views

What effect would a radical gravity change have on plants and fungus?

In relation to this question, what would plants do if they were taken from their environment to another gravity level, in particular zero g. For example would the daisy manage to grow higher ...
9
votes
7answers
2k views

Infinite tube world

I'm inspired by this question and was thinking that it is nigh impossible for sun, moon and star to exist in this world and even if they do, there is no way to sun and moon to orbit and create day-...
8
votes
2answers
402 views

What is the tallest mountain possible in any gravitational environment?

In world building it is often interesting to consider extreme landscapes – how tall can a mountain be on Earth for example. But what is the tallest mountain possible in any gravitational environment? ...
6
votes
6answers
831 views

What would happen to the Moon if it was lowered onto the Earth?

An absolute madman of a scientist tractors the Moon from it's orbit, and carefully lowers it through the Earth's atmosphere and gently brings it to rest upon the Earth's surface. There is no reentry, ...
1
vote
2answers
262 views

Using temperature to contain an atmosphere?

So, I was looking at the temperature variations in Earth's atmosphere and noticed that it gets extremely cold in some of the upper portions. So I was wondering, could a low gravity world hold onto an ...
35
votes
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 ...
23
votes
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 ...
19
votes
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
votes
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 ...
9
votes
4answers
9k views

If the gravity on earth were different, how would the human body change?

If the gravity on earth was different, how would our bodies change? For this question, assume that gravity was five time stronger (5G) from the beginning of the Earth. Would a human-like body still ...
17
votes
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 ...
11
votes
2answers
346 views

Technological adaptations for colonization of a higher gravity world

Suppose humanity found a rocky planet outside the solar system. It is in the habitable zone of its star, has breathable air, clean water etc. A true paradise. Only problem is, its surface gravity ...
9
votes
2answers
3k views

How long can humans survive in increased gravity?

One premise of my current planet-in-progress is that certain locations in the universe are inherently tied to my PIP. For example, all the people and things that have vanished in the Bermuda Triangle ...
17
votes
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 ...
15
votes
5answers
582 views

Internally consistent grav-plating

So in (a lot of) sci-fi we have magic gravity that gives up and down and layer-cake decks, and nice and easy set design for the TV studios. I’m actually pretty much okay with this, but what rubs me ...
12
votes
2answers
464 views

What is the smallest planetary mass that can prevent 'me' from flying off into space?

I have a series of astronauts landing on an asteroid. I'd like to know the threshold of mass for them to not fly off into space. Specifications: Assumption is all astronauts are under 180cm, 80kg. ...
7
votes
1answer
813 views

How Would It Feel To Walk On A Rocheworld?

A while back I saw this video talking about the habitability of double planets and Rocheworlds. I haven't seen any questions about the latter case here, so I decided to take a swing at it. For some ...
15
votes
3answers
2k views

Would gravity be constant inside a Bernal sphere?

Suppose one constructed a Bernal sphere, similar in design to that described in this article and this article at the National Space Society. If the sphere was simply rotated on a single axis, would ...
10
votes
5answers
3k views

How fast would a planet have to be spinning for the centrifugal/centripetal force to cancel out the force of gravity near the equator?

So, I know that on the planet earth, the force of gravity is actually slightly less nearer the equator, due to the Centrifugal Centripetal Spinny Force. Not by a whole lot, but by some small amount. ...
9
votes
3answers
12k views

If Earth's gravity suddenly became stronger, how would we cope?

If the force of gravity at the Earth's surface suddenly became 2 times stronger, how would the environment and humans cope? I'm guessing a lot of flying creatures would suffer, but what would happen ...
6
votes
6answers
731 views

Methods for simulating low gravity on high-g planets

There are a lot of solutions for living in low gravity environments. (e.g. centripetal acceleration, linear thrust, etc.) But what about living on high gravity planets? Is there anyway to build or ...
5
votes
8answers
767 views

How can a small planetoid hold an atmosphere under artificial means?

Edit: Before I give up on this I wonder how could an advanced civilization create conditions on a small planetoid (Ceres sized?) to keep an Earth level breathable atmosphere? It seems like its ...
4
votes
2answers
1k views

Artificial gravity and inertia negation

In my universe, spaceships use a device that can generate a bubble of gravity that is homogeneous and unidirectional. You can manipulate the direction and intensity of gravity in any way you want. The ...