If the center of the earth was hollow what would happen if you stood in it?

[Beamin]

Say it was 100ft(32.74833495735m) wide hollow pit and you could go inside it. Would you float in the center being pulled from all sides from gravity or would you be able to walk around the walls in a circle?

[Rerouter]

It would be like being in microgravity, in any case there will be a bias to a certain side, so you would come to rest on the wall of the sphere, technically walk, but difficult,

[newbrain]

It would be like being in microgravity, in any case there will be a bias to a certain side, so you would come to rest on the wall of the sphere, technically walk, but difficult,

No

Sorry for the lazy answer, but I spent all afternoon and part of the evening doing integrals with my daughter...

[Rerouter]

I was working on the premise that due to large chunks of crust sunken in the mantle, the center of mass of the earth is constantly shifting, as this makes it a non uniform sphere, you would be biased to 1 or more points,

[Electro Detective]

That's the devils hangout and soul storage of trolls, serial sinners, traitors and sell outs     

stay up here as long as you can, it's a trip you don't need, even to curb curiosity   

[Cerebus]

It would be like being in microgravity, in any case there will be a bias to a certain side, so you would come to rest on the wall of the sphere, technically walk, but difficult,

No

Sorry for the lazy answer, but I spent all afternoon and part of the evening doing integrals with my daughter...

The Earth is not a spherical cow in a vacuum uniform sphere, it is an ovlate spheroid, so there is unequal distribution of mass meaning that you'd experience a slight force in the direction of the equator which, being roughly annular, would tend to centre you in the hollow (if you drift out of the plane of the equator that plane would seem attractive to your mass).

As to what would happen – you'd be crushed and fried. The temperature of the Earth's core is approximately 5700 Kelvin, well in excess of the boiling point of iron at atmospheric pressure (3134 K). The pressure at the core is estimated to be 3.3 - 3.6 million atmospheres. Under any vaguely realistic scenario you'd die instantly there, even if you were unrealistically transported there instantaneously by Mr. Scott in a super-dooper environment suit.

[TerraHertz]

I'll go with crushed virtually instantly. Even if somehow there was a cavity at the center, in which you hoped to experience near zero-G, that cavity couldn't be maintained by any conceivable physical barrier. The cavity would implode in nanoseconds. You'd probably be compressed to some pretty impure kind of diamond.

Btw, define 'center'? Do you mean the physical center (averaging radii to Earth's uneven surface), or the gravitational center?(Which if you include the Moon, is a point that orbits around the physical center. Even more complex if you include the Sun and other planets.)

[Rerouter]

I was taking it as a thought experiment, e.g. you find a teleporter to an unobtainium structure near the center.

A similar though would be what would happen in the center of a large asteroid, the net effect is the same.

[Halcyon]

I was taking it as a thought experiment, e.g. you find a teleporter to an unobtainium structure near the center.

A similar though would be what would happen in the center of a large asteroid, the net effect is the same.

Thought experiments are fun. Probably why most of us enjoy Back to the Future. Imagine taking your shiny new smart phone back 50 years (and magically have it work), could you imagine the looks on people's faces? It's fun to think about.

This was also largely the reason why I enjoyed the 'Spellbinder' children's television series as a kid.

[Distelzombie]

It could look like this if you'd survive: 0:29+

[Brumby]

Would you float in the center being pulled from all sides from gravity

This, if you were stationary.

or would you be able to walk around the walls in a circle?

You could only do this if you were walking quickly enough (or running) to create a sufficient "centrifugal" force to counter the walking action.  Gravity from the mass above and below the plane upon which you were standing would, for the most part, cancel out.

[Cyberdragon]

I was taking it as a thought experiment, e.g. you find a teleporter to an unobtainium structure near the center.

A similar though would be what would happen in the center of a large asteroid, the net effect is the same.

You use The Fall from Total Recall.

[calexanian]

+1 for essentially neutral gravity, and so much heat and pressure, you would not want to be there.

[Electro Detective]

I was taking it as a thought experiment, e.g. you find a teleporter to an unobtainium structure near the center.

A similar though would be what would happen in the center of a large asteroid, the net effect is the same.

You use The Fall from Total Recall.

...get the brakes checked and cleaned first !   

[KL27x]

Force of gravity is proportional to the inverse of radius squared. If you're at the center of the earth, the force of gravity is acting on the mass of your body with a huge amount of force. So imagine your belly button is at the center. Your head is barely 1 meter from center. That means your head weighs 10 million pounds, and your spine ain't that strong.

So even if you had a magical chamber in there to make the pressure 1ATM @ 70F, regular atmosphere, you would die instantly. The force of gravity would crush you. And no, you wouldn't be able to walk around the walls of the chamber, even as a zombie. Your mangled corpse would ball up in the gravitational center of earth, which would presumably be at the exact center of the chamber.

[Rerouter]

KL27x, you have any math supporting that?

The premise of this idea is that you are attracted in all directions (more or less) equally, thus the forces cancel,

On the surface, the entire mass of the earth (via vector sums) pulls you in to the ground without crushing you (if your skydiving or piloting an aeroplane you would be the exception due to rapid deceleration)

As to why there is insane pressures in the center of the earth is not due to gravity at that point, but rather gravity acting on the mass further out being pulled towards it,

The reason why the atmospheric pressure drops as you go up is a simple way of seeing this effect, same if you go diving in the ocean, the mass of the water above being accelerated by gravity is what creates the pressure. this continues down to the center, increasing the pressure, but not the gravity

As you head towards the center the vector sum of the acceleration become smaller, due to more of the earths mass being above you and to your sides. rather than beneath you,

https://ux1.eiu.edu/~cfadd/3050/Ch09Gravity/GrvFld.html

The link above gives a good starting point.

[Brumby]

Force of gravity is proportional to the inverse of radius squared. If you're at the center of the earth, the force of gravity is acting on the mass of your body with a huge amount of force. So imagine your belly button is at the center. Your head is barely 1 meter from center. That means your head weighs 10 million pounds, and your spine ain't that strong.

So even if you had a magical chamber in there to make the pressure 1ATM @ 70F, regular atmosphere, you would die instantly. The force of gravity would crush you. And no, you wouldn't be able to walk around the walls of the chamber, even as a zombie. Your mangled corpse would ball up in the gravitational center of earth, which would presumably be at the exact center of the chamber.

Sorry.  That is absolutely incorrect.

The proof comes from the sum of the gravitational effects from all of the components being equal to the gravitational effect of the whole.

Mathematically, this would involve an integral - but we can see the trend of such a calculation by slicing the Earth in 3 orthogonal planes to create 8 segments.  Calculate the gravitational pull of each segment and you will notice the spherically symmetric segment will have the same (or close enough to for this exercise) magnitude but opposite sign.  As a result, the sum of all 4 pairs will be zero - thus the gravitational pull at the centre of the earth will be zero.

[KL27x]

No, you don't need to be crushed by the pressure of the magma. The force of gravity would kill you by itself.

If you landed on the surface of a black dwarf, you would die instantly in the same way. You would weigh so much, your body couldn't support itself.

Pressure would kill you, too. But the force of gravity would be enough to do the job, by itself.

You know what happens if you take an MRI and there's a steel pin in your head, right? Imagine the MRI machine is 1 million x stronger and your whole body is made of iron.

The radius of the earth is nearly 4000 miles. At the surface you weigh 200 lbs. 3 feet away from the center, your body weighs 9.91 x 10^15 lbs.

So your head is gonna weigh about 1x10^15 lbs. And your feet are gonna weigh 1x10^15 lbs in the other direction. And close to your navel, the weigh of your kidneys, for instance, is going to approach infinity. 

Mathematically, this would involve an integral - but we can see the trend of such a calculation by slicing the Earth in 3 orthogonal planes to create 8 segments.  Calculate the gravitational pull of each segment and you will notice the spherically symmetric segment will have the same (or close enough to for this exercise) magnitude but opposite sign.  As a result, the sum of all 4 pairs will be zero - thus the gravitational pull at the centre of the earth will be zero.

Ohh, yeah. I see where I am wrong. That's cool.

The reason why the atmospheric pressure drops as you go up is a simple way of seeing this effect, same if you go diving in the ocean, the mass of the water above being accelerated by gravity is what creates the pressure. this continues down to the center, increasing the pressure, but not the gravity

I contend that if you climb high enough on a pole, you will weigh less due to force of gravity depending on the inverse of radius squared. This is one of the reasons that the atmosphere is less up high. But I see your point. The difference in going down a mineshaft is that you have mass above you, too.

So if you were magically at the exact gravitational center in a special chamber, then yeah. You ought to be fine. I wouldn't be the first volunteer, though.   

[Electro Detective]

Force of gravity is proportional to the inverse of radius squared. If you're at the center of the earth, the force of gravity is acting on the mass of your body with a huge amount of force. So imagine your belly button is at the center. Your head is barely 1 meter from center. That means your head weighs 10 million pounds, and your spine ain't that strong.

So even if you had a magical chamber in there to make the pressure 1ATM @ 70F, regular atmosphere, you would die instantly.

The force of gravity would crush you. And no, you wouldn't be able to walk around the walls of the chamber, even as a zombie.

Your mangled corpse would ball up in the gravitational center of earth, which would presumably be at the exact center of the chamber.

I experienced those same effects after accepting silly advice and joining Facebook   

As soon as I got out of that mindless lemming social media fiasco, the zombie symptoms faded and I could walk, talk and think normally again 


Coincidently, a lot of browser ad junkery went away too, hmmm   

[rbm]

Minute Physics did a video on this falling through the earth, but mentions the physics on your body at the centre of the earth, which should answer the question.

[StuUK]

Say it was 100ft(32.74833495735m) wide hollow pit and you could go inside it. Would you float in the center being pulled from all sides from gravity or would you be able to walk around the walls in a circle?

Not possible the Earth is flat apparently..... 

[Rerouter]

If you landed on the surface of a black drawf, what would kill you is the pressure gradient on the materials you are composed of, due to the acceleration of gravity by that dense mass, your neck cannot support the weight of your head, and causing more problems as you move down your anatomy.

same deal if you put a cup of water on the surface. the approximate acceleration is about 10,000 G's of acceleration near to the surface of an earth sized black drawf, this is overlooking the fact that the surface is not defined as a solid.


So a standard cup of water, lets say filled 10cm high, that would have 10 Bar of pressure between the top surface and the bottom.  (10 atmospheres, or 140 psi, whichever takes your fancy),
Now a humans blood vessels will start bursting somewhere when they experience a pressure of about 2.1 bar (relative to surrounding tissue), so its not hard to see why even lying down it would kill you.

Cool fact I learned while creating this message, the average person would suffer multiple burst blood vessels in there feet, if standing up in a 1.6m pool of metallic mercury, (ignoring the poisoning risks) and start popping arteries if they where a little over 2m tall in a 2m tall pool. (in either case you would not be comfortable, the buoyancy force would nearly rip your feet off if they where anchoring you to the bottom)

Ok back on track, the radius math applies on the assumption you can treat both objects as point masses of infinite density. When you have one inside the volume of another that math can no lnger be used (its assumptions are broken), and does require falling back to integrals of acceleration for the distrubution of mass around you.

Edit: Re-checked my math, in the mercury pool, them feet are coming off, the ankle stops being connected to the leg at around 8KN of force, the pool would have 95... so... fun times ahead for science. and I question the sanity of the researchers who had to put a number to that.

[Rerouter]

StuUK, are you saying a flat earth does not have a center point? and that you could not dig down at that center point far enough down to support a 100m radius sphere?

If the earth was disk shaped the same effect would occur using the currently popular mechanics of gravity, If you assume a disk being uniformly accelerated at 10m/s then well your stuck at the bottom of your sphere at 1G.

[KL27x]

Ok back on track, the radius math applies on the assumption you can treat both objects as point masses of infinite density. When you have one inside the volume of another that math can no lnger be used (its assumptions are broken), and does require falling back to integrals of acceleration for the distrubution of mass around you.

Perfectly stated. And very interesting about the pool of mercury.

Even before reading your comment, I sensed I was missing a piece of the puzzle, because a black dwarf can make a black hole (or something like that), but a star of the same mass doesn't. Difference in density.

So... if you put your magic chamber in the center of a black dwarf, would you explode?

[Rerouter]

If you put a magic chamber in the center of a black dwarf, most of the acceleration is cancelled, there will be mass imbalances and as you approach any wall of the sphere you would experience attraction to that wall,

For actual numbers I cannot find easy tools to calculate it, however I am of the opinion you could walk inside it, and any height you can jump to will not break your legs,  (same applies on other planets aswell, just way harder to do a clean landing without practice)