Conditions at the Centre of the Earth

[Dale]

Yes, that does make sense, but it isn't what I was thinking. Since it is entirely a work of fiction I think either is fine, but obviously the higher the temperature the lower the density and the more reasonable the numbers.

 

[John100]

Guys, thank you all for so much input and erudition. Frankly, I thought there would be a simple and straight forward answer. It's good to know that scientific debate is alive and well. I find it interesting that things, including air, are all trying to get to the centre of the Earth, but when they get there, if they could, through our theoretical tunnel, they would find that the force wanting them to be there has vanished. But the air would still express a sort of memory of that force through its pressure.
Now, how about a tunnel to the centre of a Black Hole? Will there be differing answers for that, or is it actually a simpler problem?

 

[Dale]

Now, how about a tunnel to the centre of a Black Hole? Will there be differing answers for that, or is it actually a simpler problem?

Yes, the pressure is infinite and even unobtanium can't hold up. Of course, even this relies on a bad assumption, namely that quantum gravitational effects are negligible. We will know more about this when we have a working theory of quantum gravity.

 

[DaveC426913]

...things, including air, are all trying to get to the centre of the Earth, but when they get there, if they could, through our theoretical tunnel, they would find that the force wanting them to be there has vanished...

Let's clear this up. The force wanting them to be there is specifically the weight of everything above them pressing down on them. That is a very real force.

Think of it this way:

You are lying on the ground, with a 10 tonne rock on your chest. Almost. The 10 tonne rock is actually sitting on a block of wood, which is in turn, sitting on your chest. The wood only weighs 5 pounds.

The weight that is right on your chest (the wood) is contributing virtually nothing (a paltry 5 pounds) to the 20,005lb. force that is crushing the life out of you. The lightness of the wood does not eliminate the heaviness of what's on top of it.

Now back to the column of air. Just because the last few hundred miles of air weighs only 5 pounds, does not mean you are not feeling the 10 tonne weight of the 3600 miles of air on top of it.

 

[Oldfart]

Let's clear this up. The force wanting them to be there is specifically the weight of everything above them pressing down on them. That is a very real force.

That seems rather misleading...

Fish swimming near the bottom of the deepest part of the ocean are not pressed down against the bottom, and a small bird would meet no resistance from the weight above it as it flew upward from the center of the earth.

OF