Gravity here in Earth (not on)

I just did a Boolean search and came up empty on what I have to say. (though i've missed threads similar to my own before, so sorry if i am repeated offender)

Anyway, I always noticed the topics in this forum about gravity and anti-gravity concepts and I have taken a keen a interest in them. And it got me athinkin about something I thought of a few years ago while in highschool: What is gravity like at the center of planet, particularly Earth? I know that gravity tends to hold us to the ground (I also thought of gravity holding the ground to us, but didn't compute) and it tends to disipate when an increase in distance from the earth or planet occurs. But I also thought it was kinda odd that lava flowed up through to the surface, I used to consider this anti-gravity until I realized the science of plate tectonics.
But at the theoritical center inside the earth would gravity cease? I think not. I think if a Rhesus monkey was placed in such a spot r times as an experiment, it would go either of two ways: 1) It would spin around this theoritic center like electrons of an atom but instead of a repeated course it would eventually reach the surface of earth and become grounded, like a spiral or 2) The gravitional forces acting on the "poor" monkey will derive from the surface of earth in every sort of direction so that it would simply rip the monkey from limb to limb and go off in all these directions.

Just wanted some feed back on what you guys think about this, if it's worth the time.

Yea it is pretty amazing that something so predominant in our lives and right there in our face day to day has yet to truely been solved. To answer your thoughts, I think we would have to know what causes gravity to work and so far we only have speculation (theories).

What ever is at the center of our planet, or any heavenly body must certainly be extreemly dense and moving slowly as everything must surely be crunched together which would make it hard for particles to move quickly I would think. Maybe its just a really big Diamond at the center.... heh

Gravity must increase as you get closer? since it decreases as you get further away. Must be intense..

I wonder if there could be tiny black holes holding suns together..

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If you found a solid rock planet, yes you would be essentially in freefall at its center. The gravity would be pulling at you in all directions at once cancelling itself out.

So in a sense as one goes deeper into the planet the less gravity there is pulling you in a single direction, because there is gravity pulling you back.

So the gravity function in its simplest form only applies to space that is external to the object. Space is stretched and warped down to the edges of the object, then it comes back up to zero as you move to the bodies center.

One problem though, even though you were losing weight, you would be under heat and pressures greater than hell.
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it has been solved... its a fairly basic physics concept

presuming the earth is a perfect sphere, which its not i know, at the center of a sphere all the forces would be canceling and "gracity" would be effectively 0.

the earth spinning really has nothing to do with gravity

the exact equation for gravity is actually gravity = (gravity constant)(mass_1)(mass_2)/(radius)^2

that being said yes your mass does help hold the ground to you, but your 70 kg compared to the 6.0 x 10^24 kg of earths mass really does not effect the equation much at all.

and that equation only work for going away from earth, for a spherical opject once you start going into it gravity drops off at 1/r instead of 1/r^2 untill it hits 0... at the center

I would go as far as saying we understand how gravity interacts on a macroscopic level, but the only quantum theory of gravity is string theory, which in itself is pretty shady, at least in my opinion. It's not even yet proven that gravity has particles.

Also, I hate the word "anti-gravity" for a couple reasons. First of all, gravitons have not even been found yet, and second, if they are found then they must have their anti-particle, but that does not mean they behave opposite of gravity. Anti-matter behaves the same way as matter, it's not like they do things exactly opposite. And my last gripe is probably the only thing close to "anti-gravity" I've encountered is dark energy.

OK, I know this is gonna make me sound stupid as hell...but here goes.

I remember A Simpsons episide from a few years back were Homer was like trapped in the "real world". the one we live in...

Anyways, It showed space as a blanket...think of it as a bed mattress that represents space and time.

If you put a bowling bowl in the middle of the mattress and place marbels on the mattess...whats gonna happen.....the marbels are gonna move towards the mattress,,,,,,

Kinda like gravity....

Hope that helps

Originally posted by Mozo
it has been solved... its a fairly basic physics concept

presuming the earth is a perfect sphere, which its not i know, at the center of a sphere all the forces would be canceling and "gracity" would be effectively 0.

the earth spinning really has nothing to do with gravity

the exact equation for gravity is actually gravity = (gravity constant)(mass_1)(mass_2)/(radius)^2

that being said yes your mass does help hold the ground to you, but your 70 kg compared to the 6.0 x 10^24 kg of earths mass really does not effect the equation much at all.

and that equation only work for going away from earth, for a spherical opject once you start going into it gravity drops off at 1/r instead of 1/r^2 untill it hits 0... at the center

U are missing the point. An equation only describes the effects of gravity and thus allows us to calculate forces etc. What we do not know is how gravity itself works.

Originally posted by ufo3

Originally posted by Mozo
it has been solved... its a fairly basic physics concept

presuming the earth is a perfect sphere, which its not i know, at the center of a sphere all the forces would be canceling and "gracity" would be effectively 0.

the earth spinning really has nothing to do with gravity

the exact equation for gravity is actually gravity = (gravity constant)(mass_1)(mass_2)/(radius)^2

that being said yes your mass does help hold the ground to you, but your 70 kg compared to the 6.0 x 10^24 kg of earths mass really does not effect the equation much at all.

and that equation only work for going away from earth, for a spherical opject once you start going into it gravity drops off at 1/r instead of 1/r^2 untill it hits 0... at the center

U are missing the point. An equation only describes the effects of gravity and thus allows us to calculate forces etc. What we do not know is how gravity itself works.

ahh, ok i see what you are saying.

well that is true, we don't know how it works, and we really don't know much about fundamental things we hold true and build on tope of.
for example we don't know where an atom has a positive part and a negative part, it just is.

its one of those things that everyone in the science community just kinda has to come to terms with and move on i guess, its something that bothers me also though

First of all I think you would have to give that poor monkey a lot of Bananas before it would agree to the experiment and equip it with a sturdy pair of Depends.

Personally, I think you're off track. If you could somehow transport a capsule to the center of the planet and have it survive the experience, I am pretty sure it would have one Earth gravity acting on it just as on the surface. The Moon has a strong effect on Earth, as we know and I am not so sure that just being at the center of a mass would negate the effect of mass attraction, or gravity.

If your theory of zero gravity at the core was true then the closer you got to the center the less gravity you would have. Half way there would be half gravity, etc. Going to the top of mount Everest would increase the gravitational effect on you. The gravity of one half of the planet would cancel out the gravity of the other half and we would all be tossed of into Space. Nope, I don't buy it, although I think it would make a good science fiction story. But you are gonna have to clean up after that monkey as I will be too busy having Pina Colada on a beach in Brazil watching the effects of Gravity on the bikini clad volley ball players.

Even according to that equation, if you're in the center of the Earth, your distance from its center is 0. Thus, plugging that in, you have a number divided by zero--which is undefined...

I think that hypothetically the monkey would be crushed. All that mass above his head is attracted to all that mass below his feet. All that stuff to his left is edging toward all that stuff to his right. May the force be with him.

If the center of Earth, the very center, were hollow, there'd be a single point where the gravitational forces sum to zero. All around you there would be slight pertubations that wouldn't really matter much.

Your distance being 0, and hence an undefined (or infinite) gravitational force, is wrong. That's a distance from the center of mass. Once you go inside something, there is a portion pulling you in, and a portion pulling you out. Gravity from the surface out decreases by the inverse square of your distance, but gravity likewise decreases when you travel inside the Earth. Think about it, on the surface all the mass is concentrated under you. Inside the Earth, a portion of it is above you. Most is still under you (that's why you can use the word 'under') but some is pulling you upwards. Eventually you get to zero.

Originally posted by Zaknafein
Even according to that equation, if you're in the center of the Earth, your distance from its center is 0. Thus, plugging that in, you have a number divided by zero--which is undefined...

I think that hypothetically the monkey would be crushed. All that mass above his head is attracted to all that mass below his feet. All that stuff to his left is edging toward all that stuff to his right. May the force be with him.

yeah... thats true :-P

and he wouldn't be crushed because he would have the forces from the earth pulling on him equally, more or less, in all directions, which is why it would be 0

Err... I'll have to disagree with you AMORY. Having been underground quite frequently I have never felt that I was being pulled up or even lighter. Nor have I felt lighter on mountain tops. I think it is a matter of scale. I don't think there is any evidence to suggest that going deper lessens gravity but I would love to see any Data that anyone could come up with on the subject and not just personal theories. Gravity is so little understood and it even drove Einstein crazy trying to figure it out.

Ive seen a program on tv which explained this quit well, one of the cool things was that if the earth was rock solid (no molten core/mantel), and a hole was drilled from one side to the other right through the core you could jump in one side and free fall picking up enough speed to pass the center then, the force of gravity would reverse slowing you down as you reach the other side. So down would litterally turn to up and youd come out at the right speed to land on your feet.

Originally posted by Terapin
Err... I'll have to disagree with you AMORY. Having been underground quite frequently I have never felt that I was being pulled up or even lighter. Nor have I felt lighter on mountain tops. I think it is a matter of scale. I don't think there is any evidence to suggest that going deper lessens gravity but I would love to see any Data that anyone could come up with on the subject and not just personal theories. Gravity is so little understood and it even drove Einstein crazy trying to figure it out.

Terapin, I'm sorry to dissapoint you, but you are wrong. This isn't a theory, this is physics.

The DEEPEST mankind has dug is about 12km. (although I know a number of married men who would say they've dug themselves deeper) Now, the density of the Earth is 5515 kg/m^3.

Now, we take all the mass above you 12km below the Earth. Let's assume that's 1/4 of a full circle (which is wayy too much, but I'm feeling generous ) You've got a mass there of 4 x 10^16 kg. Appreciable. Except, that entire mass would provide an acceleration upwards of 0.07396m/s^2, compared with 9.81 m/s^s on the Earth's surface. And you most certainly weren't even close to that deep.

Likewise, let's assume you were on Mount Everest which I'm willing to bet you haven't been on (8850 m). Now, at that height, your radius would be that PLUS the radius of the Earth (6380 km) which is roughly 6388.85km, for a total accelerating force downwards (using the mass of the Earth which is 6x10^24 kg) of 9.80464, compared to 9.81 at the surface.

There's your data right there. Highschool physics.

Originally posted by Terapin
Err... I'll have to disagree with you AMORY. Having been underground quite frequently I have never felt that I was being pulled up or even lighter. Nor have I felt lighter on mountain tops. I think it is a matter of scale. I don't think there is any evidence to suggest that going deper lessens gravity but I would love to see any Data that anyone could come up with on the subject and not just personal theories. Gravity is so little understood and it even drove Einstein crazy trying to figure it out.

Actually, there's plenty of evidence as Amorymeltzer says. Now, you might not have hauled a scale around with you, but researchers have done this very thing. The amount of change is fairly small until you get down (or up) a considerable distance.

And gravity did not "drive Einstein crazy." It's simple, basic physics and he would have had no problems with the calculations for Earth.

Gravity drove Einstein crazy because he could not fit it into a grand unified theory. Sure we can measure the force of gravity but we really have no understanding of how it actually works. How does one mass interact with another mass over a distance? What is the basic mechanism involved? NO one has found a Graviton or explained just what is occurring in the space between the two masses. There is a conceptual model of a weight on a membrane like the bowling ball in a mattress that creates a gravity well, but that is just an abstract way of thinking about it. Thus far no one seems to have an explanation that fits in with everything else. Einstein spent years trying to figure it out and never did and it irked him greatly.

OK so you have educated me about how gravity does indeed vary with Depth or Height from the center of the Earth and I thank you for reminding me that. I still have a hard time getting my head around the Idea that the center of the Earth in essentially a zero gravity point. I don't think the mass is evenly distributed enough to create that. We do know that the Gravity of the Earth is not equal in all places on the surface and that it does indeed undergo localized changes. They are currently observing an unexplained gravity change near parts of the Equator. (I forget exactly where, but I did post details on this in another thread somewhere but an ATS error deleted the majority of my posts recently) My guess is that the theoretical "zero G" area sloshes around a bit and is never stable.

Originally posted by TerapinMy guess is that the theoretical "zero G" area sloshes around a bit and is never stable.

Well, yeah, becaue mass (us, for example) is always moving, but the majority of it is the Earth itself, and things like people make little difference. The point of 'Zero G' is always at the center of mass, which can move. If you do the math, qualitatively, and think about it, you'll realize pretty quickly that it has to be zero at the center of an evenly distributed sphere.

Oh, and as for finding gravitons, it's not so simple. Massless particles moving at the speed of light that are infinitely small. Real hard. Especially since it could be wrong, especially on the macroscopic level.

[edit on 4/25/2005 by Amorymeltzer]

I was also wondering if it is possible for the monkey to collapse into himself. Say the force of gravity was so overwhelming that the forces closer to his feet forced his head towards his feet, vice versa for his feet and some how when the force becomes unbareable for his body to mantain form, he simple collapses, almost like a suction or what occured in Lord of the Rings when the black knight was killed by the woman. In a sense, he would simply disapear from existence and fade into oblivion and disperse into complete energy.
Now that we have discussed the application of gravity at the 'center' of the planet, how may this correspond if at all to the actions inside an atom or a human. May it be our soul that lies in the center of our body?

Originally posted by Frosty
I was also wondering if it is possible for the monkey to collapse into himself. Say the force of gravity was so overwhelming that the forces closer to his feet forced his head towards his feet, vice versa for his feet and some how when the force becomes unbareable for his body to mantain form, he simple collapses, almost like a suction or what occured in Lord of the Rings when the black knight was killed by the woman. In a sense, he would simply disapear from existence and fade into oblivion and disperse into complete energy.

Nah, but good movie. Near a black hole, the tidal forces of gravity are so great that the force is so different from your head and feet that spaghettification occurs. What you're describing would be if his feet were massive, really really heavy. In this case, no, in fact his head would (if the feet were massive enough) crash into the feet creating a relatively spherical shape. No disapearing.

Now that we have discussed the application of gravity at the 'center' of the planet, how may this correspond if at all to the actions inside an atom or a human. May it be our soul that lies in the center of our body?

Wha?! You won't find scientific proof for a soul, especially using the fact that the center of mass is useful.