I went down to the bottoms of the mountains; the earth with her bars was about me for ever: yet hast thou brought up my life from corruption, O LORD my God.(Jonah 2:6) KJV
Jonah gives us direct observation of the pillars of the earth, he calls them bars. Something directly observed is called empirical. Thanks to Jonah the pillars of the earth aren’t metaphorical nor theoretical, they’re empirical.
We’ve used a reference to the sides of the pit to ascertain that the pit includes the Earth’s core and the great gulf of open space around it. The bars of the pit refers to “the Earth with her bars,” which were seen by Jonah.
This is an eye-witness account of the internal structure of the Earth. We have to conclude that Jonah drowned in the sea and was resurrected in the belly of the whale. However, for a brief period of time, he was actually in sheol, hell, in the same location as were Abraham and Lazarus in Luke 16:19-31. He saw for himself what the interior of the Earth looked like. To him the pillars of the Earth looked like bars.