Gravity

[jerryo]

explain gravity please

example:
if i dig a hole a few feet deep and walk to the edge and slip, i will fall into it
descending until i land at the bottom of the hole

(theoretically) if i dig a hole from one side of the earth to the
other side of the earth...what will happen if i fall in it ?

whats 'there' that pulled me into the hole in the first place..should disappear
with my removal of the dirt while digging the hole.

the hole i dug should cancel the mysterious 'gravity'

[Tormod]

The hole won't help you much. If you could theoretically dig a hole straight through the Earth it's center of gravity would be at the center of the Earth. So you'd fall and bounce back up, a little bit shorter every time, until you end up at the bottom.

The gravitational pressure at the bottom will crush you, however. There is no known materials that can cancel the force of gravity.

[damocles]

explain gravity please

example:
if i dig a hole a few feet deep and walk to the edge and slip, i will fall into it
descending until i land at the bottom of the hole

(theoretically) if i dig a hole from one side of the earth to the
other side of the earth...what will happen if i fall in it ?

whats 'there' that pulled me into the hole in the first place..should disappear
with my removal of the dirt while digging the hole.

the hole i dug should cancel the mysterious 'gravity'

I can't tell you what gravity "is".

I can tell you that if you fall through the hole drilled through the rotational axis of the Earth and if you aren't vaporized by the planet's internal heat you will undergo oscillation with period moment similar to(in a linear vector movement fashion) that of a foucalt pendulum or an oscillating spring, that over time you will find the distance you move back and forth through the center of mass(though the time interval will not decrease) decreases until you come to rest at the "center" of mass. That may take a very long time assuming no friction.

[jerryo]

thanks for your reply

what exactly is at the center of the earth ?

what substances make up this 'gravity' ?

you mentioned "There is no known materials that can cancel the force of gravity."

has any scientist ever tried to cancel this force or change its behaviour ?

if it can bend light it must be powerful....

[jerryo]

...somehow i did imagine falling past the center and being pulled back and forth (like a pendelum clock) until i rested at the center

i imagined it to be a very violent ride

gravity must certainly be the ruler of the universe !!!

[Tormod]

Originally Posted by jerryo

you mentioned "There is no known materials that can cancel the force of gravity."

has any scientist ever tried to cancel this force or change its behaviour ?

Of course. Most of them are mad scientists like the guy in the Back to the Future movies.

if it can bend light it must be powerful....

Actually, gravity is the weakest of all the forces of nature (ie, the strong and the weak nuclear forces, the electromagnetic force, and gravity). The other forces are much, much stronger.

If you fall from orbit to the ground, for example, gravity spends quite a while pulling you down. But the electromagnetic forces in the matter that makes up the ground will squash you in no time.

[damocles]

Jerryo;

First of all your questions really requiire answers from a physicist.
I am just an average guy when it comes to questions like this; but I'll give you what little I understand and trust that those who know this subject better will correct any errors I make so that both of us can learn.. D.

As I understand the state about what we know about gravity;
-it is the weakest of the four binding forces.
-it is the only force besides electromagnetism that seems to have an unbounded(within observer detection threshhold range) effect. Its strength though decreases with distance between objects.
-it is an asymmetric force(unlike electromagnetism) in that it has no repulsor effect associated with it known.(I may have to eat those words as there appears to be a "spatial inflation effect" observed recently that seems to be speeding up the expansion of the universe that the smart crowd are trying to somehow tie to gravity. Google vacuum energy or zero point energy for further explication. D.)

Since "gravity" seems to be tied to the property of mass and that in turn is a property we associate with "matter"(though if you were to see compressed "energy" in the densities that we see 'matter" you would have "gravity". Its crazy; but true!) There is nothing we know in existence that should be able to screen its effects unless we can find a way to do that with a binding force.(Good luck with that one! The energy densities needed to cancel the effects of gravity haven't been seen since the "cosmic egg".) In that case, all that would happen would be that gravity merges with one or all the binding forces at that moment and at that energy density.

Gravity refracts light slightly due to its weak interaction with the photon. The truly powerful force that dominates the universe at the moment is light. It is the means by which most volumetric information is transferred among matter.

For a quick basic primer, try this guy;

http://insti.physics.sunysb.edu/~siegel/plan.html

Pay close attention to what he writes abouit string theory.

ADDENDUM
The center of the Earth appears to be a liquid metal nickel iron core hotter at its center than the surface of the sun(6000 degrees kelvin) and maybe a hundred to a thousand times denser and harder than the most compressed material we have yet discovered or manufactured in our laboratories. It is a realitivly massive magnet at least two thousand kilometers in estimated radius-probably more. it is fair to say that the Earth is a spherical lump of iron covered by a mostly aluminum and silicon shell with a smidgeon of hydrogen carbon oxygen, some nitrogen and other trace elements providing a liquid and gas skin.

[Jay-qu]

basically with gravity the more mass the more force. so all materials pull the same - the center of the earth is primarily nickel and other metals - very dense, very hot. if you did have that hole going through as you fall your acceleration will slow down and eventually reverse becuase of the mass now above you... as far as canceling the force of gravity - one wouldnt know where to start, so as tormod said its a job for mad scientists

[emessay]

Originally Posted by jerryo

...somehow i did imagine falling past the center and being pulled back and forth (like a pendelum clock) until i rested at the center

i imagined it to be a very violent ride

gravity must certainly be the ruler of the universe !!!

Yes Jerryo, I agree with you that gravity must certainly the ruler of the universe, and most of mysterious like what's really blackholes functions to create gravity equlibrium of universes, etc and etc.

Like these quotes :
Einstein said matter pulls on the fabric of space-time around it. That warping is called gravity. He also said the movement of matter, such as the rotation of a planet, would send out ripples across space. Those ripples are called gravity waves.
David Shukman : "Scientists believe gravity moves through the universes in the form of waves"

Does universe gravity require something like channel to 'flow back' ? Where to flow back ? Is universe expanding or flowing back to somewhere ? Like rivers on earth flow back to blue ocean. Maybe..................

[starbuck]

If gravity is the weakest of all forces how do you explain blackholes, where nothing can escape not even light. I would think that it can be very strong.