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Questions tagged [physics]

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

233
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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 ...
124
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23answers
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What could people notice about someone who is two times as dense as a regular person?

I've got a group of magical people living mostly incognito in an ancient society. They look and act exactly the same as regular people, but they are really magicians, and a side effect of having those ...
101
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18answers
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What would make scientists realize they were on a flat world?

Scenario: While poking around in an alien ruin, scientists discover a gateway which offers instant transportation to an Earth-like world. The Observed World: The gateway leads to an area that is ...
100
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24answers
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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, ...
98
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10answers
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Would planets be cubic in my “cuboverse”?

Summary The main idea behind the "cuboverse" is that spacetime distances are measured by (something close to) the sup norm or infinity norm. Under this norm, spheres (the set of points at a fixed ...
86
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13answers
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0g pool: can I keep a big ball of water in space?

I have a super luxury space hotel. It has artificial gravity in the living and shopping area and 0g in some parts of the recreational area. There is a 0g pool available for the guests. I want it to ...
77
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17answers
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Would a 'World Tree' be feasible in real life?

A livescience.com article claims that trees can reach a theoretical height of 400 to 426 feet (122 to 130m). This is due to the tree being unable to carry water up to the top at that certain point due ...
72
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14answers
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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 ...
71
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25answers
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How can you possibly stop/kill a person who has the ability to stop time? [closed]

Let's say we have a character (let's call him Nelson), who can stop time and let's pretend like it's possible and comfortable for him to do it. He can see and move in stopped time, can apply force to ...
68
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18answers
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Mineral that explodes when cooling down

While playing old games, I encountered a friend I knew from SciFi series and games alike, the Merculite missile. While thinking about what Merculite might actually be (and linking it to a mineral from ...
64
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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 ...
62
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12answers
12k views

How can I get my DeLorean to 88 miles per hour without a train?

I got pulled into 1885, just like Doc and Marty (Or I'm one of them, assuming I can get IP rights :)). I need to go back to the future, which means that I need to get my Ford Pinto time machine up to ....
60
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10answers
15k views

If reality were frame-rate based, how could we detect it?

Inspired by this question regarding reality as simulation and this question about a continuous time line, it made me wonder: if our time were indeed like a high frame-rate simulation, how could we ...
57
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10answers
12k views

What would it feel like on the surface of a planet while it collides with another planet?

Let's say that something horrible has happened and a Mars-sized planet is knocked out of orbit and is hurtling towards an Earth-sized planet. How much time will they have? How will this affect the ...
55
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7answers
12k views

How fast would a sword need to be to avoid getting blood on it?

If a sword were to be swung horizontally, through the torso of a human being, how fast would it need to be to not have blood on it after the swing? Assume the sword and its user are together able to ...
53
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13answers
15k views

An infinite train circling the planet that never stops

As a way to travel fast, my Earth-like planet is going to have a special train, circling it (the axis of the 'tracks' is aligned with the planet's axis of rotation). The thing about this train - it ...
50
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9answers
11k views

Could you have more than one building in the same spot by “stacking” them in 4th dimensional space?

In my universe a 4th SPACIAL dimension exists around our 3 dimensions. I'm playing with ideas for a society that has access to a 4th spacial dimension and am currently thinking of what they would be ...
49
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27answers
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If a large space ship crashes on a planet, what could kill passengers without obliterating the ship?

The situation I'm considering is as follows: A large research vessel with a crew of about 100-200 attempts to land on a potentially habitable planet, but something goes wrong during the descent. A ...
48
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12answers
7k views

How would you know your floating island was losing altitude?

The question: What realistic environmental signs would telegraph to the occupants of a floating landmass that their home was slowly losing altitude? The planet: I'm working on a story that takes ...
47
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3answers
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Let’s say a 1 ton (US) sphere of tungsten moving at 99.99% the speed of light hits earth, what happens? As specific as possible

What kind of destruction would it cause? I’m assuming it’d be rather significant, could it shatter a tectonic plate? The crust? How would the oceans fare? Would the planet be able to catch the ...
47
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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 ...
45
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6answers
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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 ...
44
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9answers
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Is there a scientifically valid explanation for a circle of islands?

A couple friends and I have started a world called Lothaucan. On this world there is a continent called Novara with a circle of islands as its key feature. (seen in the mid-left of the image) Is ...
44
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6answers
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Can I use a trebuchet to launch satellites into space from a lunar colony?

I've got a lunar colony that struggles to obtain resources, so they're looking for ways to launch satellites into orbit without using up a bunch of rocket fuel. One plucky engineer has suggested ...
44
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11answers
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What would happen if the Earth struck a tiny but immovable object

We are living on this big lump of rock called the Earth, drifting ever so continuously through space. Now imagine a tiny but immovable object in space, a single atom of 'unexplanium', locked in space-...
44
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4answers
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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 ...
44
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9answers
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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 ...
43
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17answers
7k views

How to prove that the solar system isn't inside of a localized physics bubble? [closed]

So, let's say that somewere out past the Oort Cloud, physics just kind of... changes. For whatever reason. Maybe space is magic, or maybe we're just in a weird sort of localized physics bubble. The ...
43
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5answers
9k 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?
39
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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 ...
39
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10answers
6k 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{...
37
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9answers
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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 ...
37
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20answers
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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 ...
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 ...
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 ...
36
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15answers
14k views

Could a really fast man catch a bullet?

Let's say that a character moves much faster (>100 x) than a bullet. If he is shot at, could he theoretically catch the bullet (and put it in his pocket) ? What happens when he touches the bullet, ...
36
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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 ...
36
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2answers
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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,...
35
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13answers
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Is there a liquid that could protect a human inside it from impact?

I am trying to figure out what kind of liquid, if any, can be used to severely impede or slow human motion without killing or severely damaging their bodies (IE if after being submerged in this liquid ...
35
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15answers
5k views

Precision Destruction by a Cosmic Being (Or how to destroy StackExchange from space)

We have a lot of weird questions come up in chat and fun comments about how we destroy worlds over a lunch break. Here is one that though I might share. You are a power that can affect cosmic bodies ...
34
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4answers
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The Heisenberg Uncertainty Ray - A Hyper-Scanning Doomsday Weapon

From what I know about the Heisenberg Uncertainty Principle, one of its consequences is that when you learn a great deal about the position of a particle, you greatly increase the uncertainty of the ...
33
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7answers
4k views

How to create an annual celestial event for a world

Yesterday while Green, Andy and I were recording new episodes for the podcast we stumbled upon a bit of a problem that we need someone with physics/astronomy knowledge to help out with. We want to ...
32
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5answers
5k views

How can it be bigger on the inside

We have these "magical" items everywhere in fiction; from the classic rabbit coming out of a hat illusion, to the TARDIS from Doctor Who, to Newest Magical Beast Newt Scamander Briefcase. These items ...
32
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13answers
8k views

Why isn't my superhuman always hungry?

I'm writing a speculative fiction story that includes superhumans. The focus is on individual characters and their daily lives, and I'm trying to maintain some consistency by not throwing all the laws ...
32
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7answers
5k views

What would an efficient swimming creature in magma be like?

This question is specifically about the mechanics of an alien creature swimming in highly viscous magma, the unlikeliness of life surviving at magma temperatures etc isn't relevant. Just imagine it's ...
31
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8answers
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Could a WWI biplane fly if it were dropped from a high altitude instead of using a runway?

A society lives on geostationary platforms at some vast height above the ground. The platforms themselves are not affected by gravity, wind, etc. Their technology has only just reached the point where ...
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 ...
31
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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 ...
31
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4answers
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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 ...
30
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12answers
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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? ...