49 votes
Accepted

Could an underground civilisation deduce the size and shape of their planet?

Trivially (It's not a complex problem, and they have access to sufficient information) but not easily (they need to do some serious engineering projects to get the data.) Steps conceptually figure ...
PcMan's user avatar
  • 26.3k
34 votes
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Black hole at the center of the planet

Your planet needs to be about 722500 times more massive than Earth for its core to undergo collapse into a black hole. Leaving aside the small detail that at this point your "planet" would ...
Darth Biomech's user avatar
33 votes
Accepted

How powerful would a volcanic eruption need to be to blast debris to the height of the ISS?

I don't think you could get a 16g volcanic bullet into space. I mean, we can get rid of the atmosphere for a moment, and recognize that $v=\sqrt\frac{E}{m}=\sqrt\frac{64365\text J}{16.362\text g}=1 ...
Cort Ammon's user avatar
  • 132k
32 votes

Could an underground civilisation deduce the size and shape of their planet?

As an underground civilization, we can assume that they have an elaborate system of seismographs. It helps, after all, to know when the ceiling is about to come down on your head. With knowledge about ...
10ebbor10's user avatar
  • 421
31 votes
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Scientifically plausible way to sink a landmass

The Islands are not Rising, the Sea level is falling. While the whole earth can not be under water, you can limit your game area to an archipelago where the starting island is slightly higher than the ...
Nosajimiki's user avatar
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30 votes
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An atmosphere that gets denser with increasing altitude, to support these flying creatures

Get rid of the planet Rather than a planet, your story can take place on an enormous space station. The cylindrical space station is under spin to simulate gravity by centrifugal force. The people ...
thegreatemu's user avatar
  • 2,412
27 votes

Black hole at the center of the planet

No A natural occurring black hole that comes into existence due to mass collapsing onto itself must have more mass than the Tolman–Oppenheimer–Volkoff limit, which has been estimated to be around 2.17 ...
The Square-Cube Law's user avatar
26 votes

Can the Little Prince's planet actually exist in our universe?

Assuming by "planet" you mean a roughly spherical body - encompassing both dwarf planets and "true" planets - then the smallest naturally occurring body is somewhere between 1 ...
Cadence's user avatar
  • 38.2k
21 votes

Impacts of a moon falling on an Earth-like planet?

What you are asking is basically the giant impact hypothesis: The giant-impact hypothesis, sometimes called the Big Splash, or the Theia Impact suggests that the Moon formed out of the debris left ...
L.Dutch's user avatar
  • 287k
21 votes

Under what conditions could a gold planet form?

Golden ring. A metal rich asteroid like 16 Psyche got too close to your planet - inside its Roche limit and the planet tore it into a ring. This asteroid is the heart of a dead planetesimal and is ...
Willk's user avatar
  • 305k
21 votes
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Is there a material lightning does not strike?

It's not the material per se which makes it lightning proof, but rather what's around it. When a difference of potential starts building up, sooner or later it will cause a discharge and produce the ...
L.Dutch's user avatar
  • 287k
20 votes

Can the Little Prince's planet actually exist in our universe?

I'll start looking at this from a slightly different perspective than Cadence's: surface gravity. Let's say that we want the Little Prince's planet to have Earth-like surface gravity. This means that ...
HDE 226868's user avatar
  • 101k
17 votes

If a world had a massive single giant world tree could it stop an earthquake?

The simple answer is "no" What we learn from studies like this is that unless the soil is perfect, roots tend to grow out more than they grow down. They would certainly have more trouble getting ...
JBH's user avatar
  • 122k
17 votes

What pressure, temperature and atmospheric challenges exist for human habitation 1 mile beneath the surface of the earth?

Use mines as examples: 1 mile deep (1.6km), is nothing compared to some modern mines. 10 minutes drive from here there is a mine that is 3.6km deep. We can make such mines livable, or at least ...
PcMan's user avatar
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17 votes

How powerful would a volcanic eruption need to be to blast debris to the height of the ISS?

No. Using mathematical predictions the maximum possible height for normal (aka non bolide induced) volcanic plume is just over 60km which is still hundreds of kilometers short of the ISS. The problem ...
John's user avatar
  • 81k
17 votes

How powerful would a volcanic eruption need to be to blast debris to the height of the ISS?

If you really want to hit the ISS, you'll need a lot of hand-waving. And even then, directly hitting the ISS is impossible for a rocky projectile thrown upwards - the acceleration would have to be so ...
LSerni's user avatar
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16 votes

An atmosphere that gets denser with increasing altitude, to support these flying creatures

Not within the constraints of our physics: as we are taught in primary school, gases tend to occupy all space in their container. This means that in an atmosphere, using a language a bit above primary ...
L.Dutch's user avatar
  • 287k
15 votes

Scientifically plausible way to sink a landmass

Mining! You don't need to create a reason for why a whole landmass might be sinking into the water... because real people already done that! As the great Tom Scott explains in his video about the ...
Samwise's user avatar
  • 4,444
14 votes
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Is an offset mountain range plausible?

It's not geologically impossible. If you want something that looks somewhat similar, there's the transverse faults located along seafloor spreading ridges that offset the ridges by sometimes long ...
Keith Morrison's user avatar
14 votes

Could an underground civilisation deduce the size and shape of their planet?

What they can do is start digging a tunnel in a straight direction, and shine a powerful light through it. How can they check that they are going straight? The always dig orthogonally to the direction ...
L.Dutch's user avatar
  • 287k
14 votes

Scientifically plausible way to sink a landmass

You could consider something like isostatic readjustment - due to glacial action. The weight of a glacier on top of a continent will depress the continent; essentially, this pushes the continent into ...
spaceisprettycool's user avatar
13 votes
Accepted

Can a liquid sand ocean exist naturally?

In reality? No. But believably? I believe so! You can't use fluid, this would coat and weight the sand and you'd quickly have mud, which is almost as solid as the dry sand in the first place. It ...
JBH's user avatar
  • 122k
13 votes

Scientifically plausible way to sink a landmass

. . . that minimal magic epoxy will disappear soon. . . The landmass is inaccessible because it is underwater. It is underwater because 1000 years ago the greatest wizards in the world came together ...
Daron's user avatar
  • 66.2k
11 votes

If a world had a massive single giant world tree could it stop an earthquake?

It would have no effect at all. Trees are not stronger than rocks (citation needed) and rocks couldn't stop an Earthquake. The Earth is already full, loaded with old roots and trees. Your tree can ...
Trevor's user avatar
  • 6,474
11 votes
Accepted

Could a robot that can survive at the center of the Earth also survive a nuclear explosion?

According to this site, the center of the Earth with its 6000° Celsius seems to be rather chilly when compared to the center of a nuclear explosion Temperatures of a nuclear explosion reach those ...
L.Dutch's user avatar
  • 287k
11 votes

Is there any scientific way a ship could fall off the edge of the world?

The problem with a cliff in the ocean a ship might fall over is that the water falls over it as well. That means that your ocean will drain vigorously until it's below the height of the cliff. You ...
ths's user avatar
  • 7,909
11 votes

Could an underground civilisation deduce the size and shape of their planet?

No, but... Thanks to the Foucault pendulum, an invention from the eponym French genius (XIX century), your civilization can follow this reasonning : The planet is spherical and it turns on itself ...
Freedomjail's user avatar
  • 1,608
11 votes

An atmosphere that gets denser with increasing altitude, to support these flying creatures

Your problem is that the nature of the universe is for heavy/dense things to be at the bottom of a gravity well and light/thin things are at the top. You can violently mix that up (see Jupiter's storm ...
JBH's user avatar
  • 122k
10 votes

Defining a superfluid ocean

You've got a few errors: Similarly, all lakes and streams above sea level are empty You'll still have lakes and streams, they just won't stay wet for very long. "Zero viscosity" doesn't mean "...
Mark's user avatar
  • 17.8k

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