Questions tagged [physics]

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

49
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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
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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 ...
24
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7answers
4k views

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 ...
41
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21answers
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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 ...
237
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22answers
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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
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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
votes
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 ...
23
votes
7answers
30k 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 ...
45
votes
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 ...
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10answers
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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 ...
39
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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/...
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5answers
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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
votes
4answers
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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 ...
47
votes
7answers
14k 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 ...
24
votes
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 ...
32
votes
4answers
62k 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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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
368 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
votes
1answer
225 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 ...
100
votes
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
votes
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? ...
14
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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
584 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
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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
votes
4answers
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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
votes
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
votes
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
votes
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
votes
2answers
1k 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 ...
2
votes
4answers
364 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 ...
40
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5answers
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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 ...
37
votes
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 ...
36
votes
2answers
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,...
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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17answers
14k 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
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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
197 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 ...
44
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4answers
7k 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
votes
7answers
6k 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
votes
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, ...
10
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1answer
1k views

What would the reaction times and or cognition speed of an alien with a photonic or partialy photonic nervous system be?

In my reading of sci-fi I came across a fascinating concept: an alien race called the Chromatics that had a partially photonic nervous system. They were described as having very fast reflexes. Now I ...
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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 ...
6
votes
3answers
376 views

What ways are there to keep a steady altitude with large fluctuations regarding load?

Setting: In my world I've introduced some science-defying material. I use it to grant the ability of flight to airships that are less Hindenburg-y and more ship-y. They are not literally ships that ...
5
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1answer
2k views

How much energy to destroy the crust of a planet?

In the Star Trek: Deep Space Nine episode The Die is Cast. A planetary bombardment scene occured where 17 shots was stated to have destroyed 30% of a planet's crust. Now obviously that's a HUGE amount ...