06-06-2006, 10:00 PM
It's no mystery. There earth's core is solid. Solid objects don't need pressure on them to keep them solid. The liquid outer core circles the inner core because of gravitaional attraction. There's pressure on the inner core because the outer core, mantle, and crust are all being pulled towards the center. Why are they being pulled by the center? Actually, they aren't being pulled by the center, but to the center. Every bit of matter on the earth is actually being pulled by all of the other matter. The average of all these forces added up create the center of gravity, the geometric point where all the matter "appears" to be attracted to. It doesn't move towards that point because it's the center, but because all of the other forces point it that direction. Imaging 2 huges planets of equal size in space. They will have a gravitaional attraction to each other, right? So they will move closer to each other. Now, if you are residing in the center of gravity between those 2 objects, you won't be pulled either way by them because the one's gravitational pull cancels the other's out. But this does not stop the planet's from moving towards you! Gravity is still in play with those 2 planets and you will be crushed once they collide. This same concept applies with the earth. Even though you wouldn't feel any of the earth's gravitational force in the center, there is still a massive amount of matter being pulling towards the center, thus creating pressure.