Earth Should Be Hollow

[Into Darkness]

Gravity increases due to mass.
As you approach the centre of the planet the planets thickness below you shrinks because obviously you are leaving behind the upper layers and approaching the bottom layers.
As this is the case, it means gravity as you approach the centre of the planet should weaken.

Therefore I was thinking, if that is the case, then gravity would reverse or should I say start pulling in a different direction.
The minute you pass the mid point of the Earth when heading to the centre, gravity should be equal on each side, or perhaps even stronger on the upper side because realistically you've got more mass on top. This should mean then that when you pass a certain point on the way down and therefore gravity becomes stronger above, everything (all rock etc) below that point should actually be getting pulled upwards not downwards.

This in theory should create a hollow centre as gravity is pulling everything upwards.

The Earth therefore MUST be hollow.

I literally just realised this whilst thinking it through.

 

[LMFAOschwarz]

Gravity increases due to mass.
As you approach the centre of the planet the planets thickness below you shrinks because obviously you are leaving behind the upper layers and approaching the bottom layers.
As this is the case, it means gravity as you approach the centre of the planet should weaken.

Therefore I was thinking, if that is the case, then gravity would reverse or should I say start pulling in a different direction.
The minute you pass the mid point of the Earth when heading to the centre, gravity should be equal on each side, or perhaps even stronger on the upper side because realistically you've got more mass on top. This should mean then that when you pass a certain point on the way down and therefore gravity becomes stronger above, everything (all rock etc) below that point should actually be getting pulled upwards not downwards.

This in theory should create a hollow centre as gravity is pulling everything upwards.

The Earth therefore MUST be hollow.

I literally just realised this whilst thinking it through.

I've got questions like this, too, to which the conventional answers don't seem to add up to satisfaction.

 

[Melakon]

Great ideas often hit us when intoxicated, but this entire premise sounds like something out of Jules Verne.

 

[gturner]

The gravity does hit zero in the center of the Earth, but the pressure is already immense. Thus it's not hollow.

If you crunch through the equations for a gravitational field inside a hollow spherical shell, it's zero everywhere inside regardless of the mass of the shell. The same calculus says that the electric field inside a conductive spherical shell is zero, because any forces following square-law attraction or repulsion completely cancel inside the hollow part of a sphere. So the only non-cancelled gravitational force felt somewhere deep inside the Earth is from the spherical depths below, which can be treated as coming from a smaller planet with the same center.

Speaking of insights, the other day I realized PV=nRT is invalid in any accelerating reference frame, such as the surface of a planet.

 

[Metryq]

Earth is a giant matryoshka doll. In the early days of the Solar system, the Earth opened up, and the Moon popped out.

 

[Into Darkness]

I would have thought that as rock is being pulled down and rock is being pulled up towards the strongest point of gravity/mass, the pressure would be at it's highest around the Earths mid point rather than centre, this midpoint would be where the pressure is highest and the rocks would become superheated and turned to magma. This liquification of the Earths mid point would cause outward expansion and splitting of the Earths crust into tectonic plates.

As the Earth was originally forming it would have been a solid rock object until it reached a size where the gravity point moved outwards to the midpoint and as the gravity point moved midwards so too would everything at the centre.
We're talking a process of millions of years if course.
Also, as the midpoint of the Earth is where the centre of gravity is and thus the location of magma, this magma as we can see made it to the Earth surface through volcanic activity. As the magma rock seeped to the surface this would have opened up space for even more rock at the Earths centre to be pulled to the mid point causing the centre of the Earth to become even more hollow

The Earths magnetic field is being produced because the rock below the magma mid point is spinning faster than the rock above the magma mid point. The Magma is a form of lubrication which allows vast speed differences.

 

[Into Darkness]

I would also say, that as the lava reach the surface and the midpoint pulled more central rock towards it, the gravity point would keep shifting outwards and the Earth would expand in size. Eventually the process of outward expansion would slow down as the material the Earth is made of took up more "space" and eventually stop and the Earth would cool down, a process which is occuring now.
So I believe it's logical to assume the Earth was once a tiny solid rock but over billions of years it expanded and became hollow due to an outward moving "shell" of gravity.

I'll try to explain better:

Stage 1: Earth is a solid rock.
Stage 2: Earths size increases as rocks are pulled in from the solar system.
Stage 3: The gravity point on Earth moves outwards as the Earth increases in size.
Stage 4: The rocks below this moving gravity shell get pulled upwards and the rock above it get pulled downwards and the magma point moves outwards too because it's at the midpoint where the pressure is highest, rock at the Earths centre and surface is cooler then the rock at the Earth midpoint.
Stage 5: This midpoint magma leaks to the surface of the Earth, increasing the area on the surface.
Stage 6: Rock continues to get pulled upwards from the centre as the released magma opens up more space at the midpoint for it to move into.
Stage 7: This process of rock movement causes the gravity shell to move outwards even more because rock/mass is moving. This causes the now hollow centre to get bigger and the Earth to continue to expand in size on the surface.
Stage 8: Rock becomes more spread out because the Earth is not as compact as it once was, this leads to the cooling of the midpoint magma and a cooling of volcanic activity.
Stage 9: Eventually the magma midpoint will cool to such a point that the inner rock earth and outer rock earth on each side of the magma midpoint wont spin at different speeds, Earth will lose it's magnetic field and the Earths surface will burn as it loses it's protection.

 

[RoJoHen]

Well, it's also a question of density. I admit I'm far from an expert, but wouldn't the Earth's core be incredibly dense from all the pressure of the outside mass. There might be more "stuff" on the outside, but the inner core is basically a huge ball of iron.

 

[gturner]

The rock above does not exert a negative gravitational influence on the rock below because its force is exactly canceled by all the rock above that's on the other side of the planet (that's calculus for you, giving exact answers to such questions).

The pressure keeps building as you go down, so that at the core it's between 50 million and 53 million pounds per square inch.

 

[Crazy Eddie]

The rock above does not exert a negative gravitational influence on the rock below because its force is exactly canceled by all the rock above that's on the other side of the planet (that's calculus for you, giving exact answers to such questions).

The pressure keeps building as you go down, so that at the core it's between 50 million and 53 million pounds per square inch.

Just making sure I understand:

The pressure is so immense at the core, but there's not enough gravity to act against that pressure, therefore the core material should expand upwards since there is not enough gravity IN the core to contain it?

Interesting thought, but it think that assumes that the Earth's mass accreted from the contraction of a spherical mass instead of, as is generally assumed, an accretion disk of material that spiraled inwards and grew that way. The core would have collected first, and other material fallen in and deposited on top of it over time. Since the material above still puts pressure on the material below (it's still falling towards the center all the time) then the core becomes much denser than the upper layers. Also, SINCE the core is denser, then it would still have a somewhat greater gravitational pull than the rest of the planet and the above material would be accelerating downwards a bit faster than the calculus alone suggests it should.

 

[Silvercrest]

Great ideas often hit us when intoxicated, but this entire premise sounds like something out of Jules Verne.

Wow! This is the second S&T thread this month where I get to say:

Where's James Mason when you need him?

 

[gturner]

Well, imagine a hollow but very heavy planet, filled internally with gas, where all the mass is in the shell (or crust). The surface gravity would be determined by it's total mass and radius, and the weight of the crust would exert a tremendous inward force.

The gravitational forces inside the hollow sphere are zero (or as close to it, if the mass of the internal gas is small), and in such a case the internal gas would have uniform pressure everywhere, just like a big steel air tank. The pressure of the gas has to support the entire crust, so that pressure will be very large. So there aren't any non-canceled gravitational forces acting on the internal gas, yet its pressure would remain extremely large, again, just like a big high-pressure air cylinder.

 

[Kemaiku]

Well, it's also a question of density. I admit I'm far from an expert, but wouldn't the Earth's core be incredibly dense from all the pressure of the outside mass. There might be more "stuff" on the outside, but the inner core is basically a huge ball of iron.

A mass of iron that is hot enough to start turning to vapour but kept in a compressed dense liquified state by the mass of the Earth on top of it pressing down in all directions. Or something like that.

 

[YellowSubmarine]

The upwards gravitational pull of the Earth layers above you is approximately zero (as mentioned, gravitational forces inside a hollow Earth add up to zero, except for the irregularities in mass), so you only feel the downward pull from the Earth layers below you.

Which is why anyone inhabiting the inside of a Hollow Earth will be weightless, and a Dyson sphere is kinda impossible – the star will wander around aimlessly inside the sphere, because there is no gravitational interaction between the star and the Dyson sphere.

 

[HIjol]

The gravity does hit zero in the center of the Earth, but the pressure is already immense. Thus it's not hollow.

Speaking of insights, the other day I realized PV=nRT is invalid in any accelerating reference frame, such as the surface of a planet.

...the almost complete equation of a Perfect Gas...my sincere question is, what would constitute an Imperfect Gas?...and I am loving this thread!...my understanding, also, is that there is very dense iron at the center of the Earth, spinning rapidly...

 

[HIjol]

Great ideas often hit us when intoxicated, but this entire premise sounds like something out of Jules Verne.

Wow! This is the second S&T thread this month where I get to say:

Where's James Mason when you need him?

He is buying some shirts...some striped shirts...

 

[JarodRussell]

Shouldn't the sun be hollow as well then?

 

[varek]

I thought the gravitational force decreased with distance. So, as you get closer to the center of the Earth, the gravitational force should increase, rather than decrease, shouldn't it? Isn't gravity what turns sand into stone and carbon into diamonds? Therefore, I do not believe the Earth could be hollow.

 

[Tiberius]

Gravity increases due to mass.
As you approach the centre of the planet the planets thickness below you shrinks because obviously you are leaving behind the upper layers and approaching the bottom layers.
As this is the case, it means gravity as you approach the centre of the planet should weaken.

Therefore I was thinking, if that is the case, then gravity would reverse or should I say start pulling in a different direction.
The minute you pass the mid point of the Earth when heading to the centre, gravity should be equal on each side, or perhaps even stronger on the upper side because realistically you've got more mass on top. This should mean then that when you pass a certain point on the way down and therefore gravity becomes stronger above, everything (all rock etc) below that point should actually be getting pulled upwards not downwards.

This in theory should create a hollow centre as gravity is pulling everything upwards.

The Earth therefore MUST be hollow.

I literally just realised this whilst thinking it through.

Not quite.

You are correct when you say that you would feel weightless at the exact center of the Earth, because there is a (roughly) even amount of mass in each direction.

But in any other location, there would be some gravitational force pulling you towards the center of the Earth, even if it is very slight.

 

[JarodRussell]

Would you feel weightless or rather feel the pressure of billions of tons of material from all directions?