Questions tagged [physics]

For questions regarding the physics relevant to fictitious worlds. General physics may be off-topic.

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49
votes
6answers
10k views

Could two planets be tidally locked to each other so close they share their atmosphere?

Could two planets be tidally locked to each other at such a small distance from one another that they share their atmosphere, and material is floating around between the two?
65
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28answers
30k views

Plausible Reasons for usage of Combat Mecha

So, assuming that the technology is readily available and that we could build these mecha as easily as we build modern tanks or planes. What would be a good advantage in using a legged (not ...
23
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7answers
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What are some plausible super materials? [closed]

Background Science fiction is rife with "super materials". Most often the materials are made from elements unknown to Current Era (CE) science. They use names that make us think of elements without ...
42
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23answers
10k views

What would be best way to re-melt Mars' mantle and core to revive its magnetosphere

Missing magnetosphere on Mars keeps popping up. Most likely caused by Mars core being cold, mantle not bubbly enough. Mars mantle is dormant, core does not move. What would be good way to get it ...
241
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22answers
42k views

What's the smallest change to physics required to allow magic?

Yesterday my 7-year-old daughter asked me: Why can't I do magic for real? I answered: because of the law of conservation of energy! And I briefly explained this law. Thus she grumbled "a single ...
30
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9answers
4k views

Is there a scientifically plausible faster-than-light communication system?

In series such as the Hyperion Cantos and Ender's Game, there exist fictional faster-than-light communication systems allowing either instantaneous, or near-instantaneous transmission of information. ...
44
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9answers
5k views

Wondering what would happen if magic was constrained by Conservation of Energy

Would throwing a fireball leave a trail of frost in its wake? Would transmuting too much lead into gold cause a small meltdown? Would collecting enough power to cast a really big spell like causing ...
45
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6answers
4k views

What happens if the sun disappears and then reappears some days later?

In the Norse prophesy of Ragnarok, Fenrir eats the sun. Considering the Earth is not immediately consumed by a supernova, it must be assumed that he swallows it whole and it just ceases to exist on ...
16
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10answers
6k views

Could humans alter the moon's orbit significantly with current technology?

A terrible virus has made most of the populations and government officials of the largest superpowers on Earth stark, raving mad, without depriving them of their intelligence. They have decided that ...
40
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4answers
4k views

Is there a scientifically sound faster-than-light travel system for a spaceship?

Recurringly in Sci-Fi spaceships manage to make it to lightspeed and above. Is there a scientifically plausible explanation of such capacity? How does it impact the spaceship's design and its ...
23
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3answers
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What colour is the foliage if the sky is violet?

This question on Physics.SE asks whether other colors are possible for the sky. I would like my planet to be inhabitable by normal humans. It has 768 days and they are living in a temperate/...
47
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7answers
15k views

What if the speed of light were 100 times higher?

Imagine the speed of light is 100 times that in our universe. Light from the moon takes about 1/100th of a second, the sunlight reaches our eyes in about 4 seconds, from nearby Alpha Centauri in about ...
23
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7answers
31k 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 ...
10
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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 ...
31
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4answers
5k views

What would happen if magic was constrained by the second law of thermodynamics

This is a followup question to the question Wondering what would happen if magic was constrained by Conservation of Energy and it's related to this post. This question asks which sources of energy ...
24
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8answers
2k views

What could cause rock formations (small stones, boulders, islands…) to levitate?

You see this in quite a bunch of movies / books (think avatar). What could be a reasoned physical explanation of such phenomenon? Would this explanation impact other things on a planet? Like most ...
33
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4answers
63k views

How big would a pair of wings need to be to allow an adult human to fly in a given environment?

Lets indulge in a bit of Mad Science, here. Assuming the world described here: Making the Enterprise Fly (60% of earth's gravity, 50% denser atmosphere) what is the wingspan needed to allow an ...
14
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10answers
2k views

Realistic Airships

I'm looking for an answer concerning a steam powered airship. The steam is generated via coal burning. The ship is propelled by an X amount of steam engine propellers (think Besler steam plane). The ...
14
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4answers
6k views

Could we still live if Earth's spin speed slowed down by 90%?

I am working on a project (The Longest Day), and I'm sure some people here have the necessary knowledge to give me some more usefull info. OK, here it is: Lets say that Earth's spinning speed ...
-1
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1answer
371 views

If the moon were made of cheese, what would Maxwell's Laws become? [closed]

This is a parody I designed after reading this question. The real point is to explain to the general reader exactly what "makes sense" or not in terms of the counterfactual hypothesis. Clearly some ...
-1
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1answer
230 views

Would a “reactive force field” be possible?

In IRL, reactive armor is a type of armor, that is created to defend the tank from non-explosives kinetic perpetrators penetrators, by blowing away the projectile with the detonation of a high ...
101
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24answers
15k views

If our universe was a simulation, what could a bug look like?

Let's assume, without revoking any of today's science, that the world is a simulation. What would a bug look like? I'm assuming that "the eiffel tower suddenly being bent at 45°" is rather unlikely, ...
21
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9answers
6k views

Plausible plasma weapons?

In a lot of science fiction, the advanced weaponry takes the form of guns firing directed bursts of plasma. These searing bolts of fire are classic ways to create weapons apparently rooted in science, ...
30
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12answers
6k views

Would pyrokinesis be an effective defense?

I've read comics in which someone with pyrokinetic powers was able to block bullets with a sheet of fire. I have three questions How hot would the fire have to be to melt a bullet passing through it? ...
15
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5answers
2k views

Physical laws for a matter-filled universe

The Setting: I have an idea for a universe that, in an inversion to our own, is filled for the most part with matter in solid, liquid, gaseous or plasma form, while vacuum and degenerate matter is ...
15
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1answer
599 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
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9answers
5k 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, ...
7
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4answers
1k views

How to convincingly explain Kaiju

This will be a companion question for How plausible is my monster?. My previous question dealt with a story treatment for a hard science and realistic take on Kaiju/ giant monsters. While that story ...
15
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7answers
2k views

Could a moon have its own satellites visible from the planet it orbits?

Say you have a planet and the planet has a moon: could the moon have visible satellites as well? I don't mean a gas giant planet, I mean something habitable by humanoids or humans. Will the moon's ...
10
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12answers
2k views

If Earth spin decreased, how can I get it spinning faster?

The question Could we still live if Earth's spin speed slowed down by 90% assumed Earth's spin speed slowed down by undefined human activities (as if climate change was not bad enough). One answer ...
4
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4answers
2k views

Energy manipulating superhero — how would it work

I want to make a superhero that can control all forms of energy. From what I've heard you can do a lot like, manipulate time and space, open blackholes, teleport, shape shift, and manipulate matter. ...
8
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2answers
2k views

Attenuation of a laser in space?

Given that a laser beam is made up of coherent light waves running in parallel in the same direction, and that space is not a complete vacuum (dust, radiation, electromagnetic forces etc.), what kind ...
8
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3answers
2k views

What Color Can the Sky Be?

A good friend of mine, who's a doctor, is very well traveled, and he told me he's seen skies of different worlds take all the colors of the rainbow (and the grayscale to boot). I suspect that he might ...
4
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3answers
503 views

How could a sentient life form move an exoplanet the mass of the Earth?

Okay. I have been piecing together the elements of another story for my school PDF newspaper (we publish one to a wiki page every two days). Yesterday I asked this question on whether a second ...
2
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4answers
386 views

Feasibility of a Synthetic Buoyancy Bladder, Used in the Air

Many fish have specialized organs called buoyancy bladders which allow them to control their buoyancy - effectively rising or sinking in the water. What if humans adapted this to use in the air? I'm ...
2
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3answers
176 views

Weather and climate of tidally locked, inhabited moon with oceans

This follows another question that brought me some curiousity about the general state of an earth-like moon tidally locked to a gas giant planet. There's been questions about a world tidally locked ...
40
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5answers
8k views

Only Three Books: Restarting Physics after civilization collapses [closed]

Global famines have dropped the population to 1 billion people and global civilization has collapsed. In an effort to save future civilization some time, you want to provide some information to kick ...
42
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1answer
4k views

What would the periodic table of a 4-Dimensional universe look like?

In this question, I asked about a universe with (amongst other things) 4 large spatial dimensions. In 3 dimensions, we have the familiar periodic table with its familiar arrangement of atoms in the S,...
37
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14answers
8k views

Can I keep our universe, but without the speed limit (of light)?

It seems like nothing can move faster than light and this is quite bothersome for interstellar travel. It takes decades in the best case to get anywhere interesting in our little Milkyway (Many ...
21
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5answers
4k views

Water-based computer

We all know that electrons behave like flowing water, e.g. that electric currents behave like water currents. We also know that modern computers use electric currents to carry out mathematical and ...
28
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2answers
4k views

How can I estimate how far into a cave network breathing is possible?

I want two populations to coexist in a world with extensive tunnels carved into the rock. One population lives in the tunnels, coming out to trade and gather food. The other is aware of the tunnels ...
26
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18answers
15k views

How might telekinesis and pyrokinesis work if they were possible?

New here! Now let me be clear: I'm well aware that telekinesis and pyrokinesis are both impossible, as I've been rudely informed on every science forum. Nonetheless, I don't just want to "make it up" ...
37
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14answers
7k views

How, if at all, can space battleships mitigate gun recoil?

I am making a game universe involving spaceships. While chewing through the implementation issues, I also keep making story and environment plans. Big battleships have big guns. However such guns ...
29
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5answers
6k views

Could a human survive 5Gs for about two days using existing or near future technology?

For purposes of this question, assume whichever body position and/or axis of acceleration is most likely to provide a successful outcome. And if it is not possible at all, what is the maximum length ...
17
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11answers
3k views

How should I calibrate and estimate pyrokinesis?

BACKGROUND I'd like to create a world that includes pyrokinesis, the ability to heat and even combust materials at a distance. This is a low-magic setting, so what I have in mind is not very flashy. ...
9
votes
3answers
200 views

Habitable environment on a big moon of a gas giant lacking magnetosphere

I am trying to figure out how to make a moon (75% of Earth size) of a gas giant habitable. To give an idea of the technological level, here are technologies the colonists have access to: fully ...
45
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4answers
8k views

How many people would have to be killed to make the streets 'run red with blood'?

For example, a street this wide to have enough blood run down the length shown in this photo? Assume that the blood isn't going down storm-drains for whatever reason and assume the stretch of road is ...
29
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5answers
3k views

Star Matter Gate Blast Radius

In an act of magical warfare, a wizard opens a gateway leading to the center of the Sun. Matter can pass through the gate freely in either direction. The gate does not last very long -- the wizard ...
13
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7answers
7k views

Will a person be able to see when he stops time? [duplicate]

Suppose there is a person who owns a device which can stop and resume time. When the person stops the time, will he be able to see the things around him? I imagine not, because stopping time will stop ...
8
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5answers
2k views

Why aren't complex devices or electronics ever built out of force fields in science fiction? [closed]

Most science fiction dealing in the subject of force fields depicts them in a similar and unsophisticated light, e.g. force fields rarely do anything besides form basic polygons to create walls, ...