# Tag Info

## Hot answers tagged physics

### Can a planet stay cracked?

There is a crack in Mars called Valles Marineris. It is about as long as the contiguous USA. And here is a 3D rendering of it: This rift is comparable to your specs in length and width, but not ...

### Can a planet stay cracked?

No, it couldn't be remotely stable, and erosion is not going to matter. Even assuming the crack got formed by some very 'gentle' process that didn't destroy the planet outright, you’ve got to consider ...
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### Can a planet stay cracked?

The volume of the hole is about 10,500,000,000 cubic kilometers. The density of Earth is about 5,518,000,000 tonnes per cubic kilometer. The mass of the hole was about 6$\cdot$1022 kg. As such, the ...
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### Can Mars disintegrate entirely in this scenario?

One part of the question says: Before the fly-over, Mars's rotation can be accelerated to up to 1 Martian day per hour if that helps Mars to disintegrate. Would that help Mars break up into pieces? ...
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### Can a planet stay cracked?

Hot Mess: This is a tricky question to answer. The first big question is, "What caused the crack?" The likely sources of the damage will seriously affect how the crack looks and how it fills ...
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### Can a planet stay cracked?

Short answer: I suggest you use a small, artifically shaped and terraformed mostly iron nickel world to have a crack which is very large absolutely and also relative to the size of the world. Long ...
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Accepted

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Accepted

### Can you survive a reduction of particle mass?

It would reduce the mass of the W- and Z-bosons in the atoms that make up your body by a factor of 1000. Which would - due to the uncertainty principle - automatically increase the range of the weak ...
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Accepted

### How would the laws of physics need to be adjusted if there really were a preferred frame of reference for FTL?

There's really nothing needed to make a privileged frame consistent with what we currently know - you just have to make it so that the privileged frame is empirically undetectable with any experiment ...
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### Can a planet stay cracked?

No, by definition. People still debate if Pluto deserves to be called a planet or not. The current definition has three elements: In orbit around the sun. Large/massive enough to reach a hydrostatic ...
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Accepted

### Can Mars disintegrate entirely in this scenario?

Yes, and no need to introduce fast rotation, or nukes or anything similar. The Roche limit for liquid bodies is $d=2.544R \sqrt[3]{\frac{\rho_M}{\rho_m}}$, where $R$ is the radius of the more massive ...

### How could I calculate the necessary power to kill a fictional beast?

Hunters and hunting theorists have developed a number of formulae for calculating killing power: https://www.chuckhawks.com/killing_power_formula-2.html You can take any of these and plug in your game....
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### Can a planet stay cracked?

No, it is not stable. It's hard to account for everything that would effect such a scenario, but just to name a few things that would happen, first, all of the liquid water on the planet would try to ...
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### Can you survive a reduction of particle mass?

A regular human has about 5 kg of blood, pumped to a pressure of about 120/80 mmHg. Suddenly you have 1/1000th of the blood mass being pumped to the same pressure. That outta hurt. The air around you ...

### Can a planet stay cracked?

Just have to start calculating pressure, gravity differences of $1500$ km depth. Pressure alone guarantees interesting things happening rapidly. With density same as earth radius $3500$ km, mass would ...
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### How could I calculate the necessary power to kill a fictional beast?

It's all about placement. Elephants are about as big as trex's, and people have hunted them with spears. Hit them right and they die. If your aim is shitty, you need an elephant gun, which is ...
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### For a planet with a given equilibrium temperature, what is the maximum pressure possible?

I'm going to answer the question of how to find the SURFACE pressure, not the MAXIMUM pressure, since you can always just get a higher pressure by digging a hole. With that caveat, here's a rough ...
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### Can a planet stay cracked?

Even Creating a "Crack" is Impossible Let alone finding a way to make it stable. The Chicxulub impact created a geographic feature roughly 20km deep and 200km around. The kinetic energy that ...
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### Can a planet stay cracked?

It's easy to calculate the maximum permanent depth of a local, steep-walled crack in the planet: $Depth=strength/(density*gravity)$. Hydrostatic pressure in the rock at the crack's bottom can be ...
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### Ballistic properties of unobtainium

Boom. The biggest problem I see with your paraneutronium is that it has no repulsive force. Neutron is stuck to neutron somehow, every femtometer. If a piece of matter hits it, the electrons sail ...
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Accepted

### Ballistic properties of unobtainium

Here's a few alternative calculations: You will have problems when the speed of sound is insufficient to carry the information of the impact far enough to dissipate said impact before the material is ...
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### Using coilguns or VASIMR as thrusters in a game

Induction furnace / coilgun hybrid. I wince at lasers and fast moving pellets. Much waste, much danger. The horror of moving parts! I propose instead that you melt your reaction mass using an ...
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1 vote

### Using coilguns or VASIMR as thrusters in a game

Vasimir might be the better option in the sense that on paper at least easily tunable when it comes to your rocket thrust/efficiency ratio. My (lay) opinion would be that assuming the two competing ...
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1 vote

### Ballistic properties of unobtainium

Okay, it seems to me we can reason roughly as follows. Take the case of a 1 m object impacting at 100 km/s (around the high end of expected natural impact speeds, assuming an object coming from ...
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1 vote

### How do I create a "magic particle" to make magic work with physics?

Dark matter Dark matter and dark energy make up most of the universe. Some planets/civilizations/people have whatever it takes to interact with it. The rest of us have no idea; it's only mass to us. ...
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