Does Gravity Exist or Is It Just a Bend in Space-Time?

[Guesser7]

No I think you would slow down slightly as you go through the crust and eventually you would burst into flames. No seriously, if you could do this initial innertia and then centifugal force would either try to throw back out the hole you entered, and you would go up and down like a piston in a cylinder, or of if you passed through the core with the inertia you would probably barely make it outside of the boundary of the molten iron core. It is really a question of balance between gravity and centrifugal inertia.

 

[DaveC426913]

i thought the shell was thin

It is as thick or as thin as you define. If your sphere is 4000 miles in radius, about the size of the Earth it could be a shell of:
- 3900 mile thickness, leaving an interior hollow space a mere 100 miles in radius.
of the Earth
- 1 mile thickness, leaving an interior hollow space 3999 miles in radius.
- 1 inch thickness, leaving an interior hollow space 3999 miles 5279' 11" in radius.

These things don't actually exist, the point of this thread is: what is the gravity at the centre of the Earth? Or, if the Earth were hollow, what would the gravity be like inside? Any question like this can be answered by studying the general principle, which is known as Newton's Shell Theory.

 

[DaveC426913]

No I think you would slow down slightly as you go through the crust and eventually you would burst into flames. No seriously, if you could do this initial innertia and then centifugal force would either try to throw back out the hole you entered, and you would go up and down like a piston in a cylinder, or of if you passed through the core with the inertia you would probably barely make it outside of the boundary of the molten iron core. It is really a question of balance between gravity and centrifugal inertia.

Assuming there were nothing blocking your path, you would fall to the centre of the Earth and continue past it, rising right back up to the surface. You would just intersect the surface of the Earth at the peak of your arc before plunging back down again. The time for one complete passage back to your starting point would be about 90 minutes - not coincidentally, that is exactly the same length of time it takes to orbit the planet if you could do it at zero altitiude.