We have developed a 3D spherical hollow Earth model (SHEM). If the Earth has experienced radial shrinkage and it's diameter decreased, we can so some simple calculations to figure out what the original radius was.
The current generation of Trekkie scientists assume that you can measure the mass of the sun from a deep space probe. That's what popular science (SciPop) is now, an inductive rationalization of the Star Trek universe.
It's very useful to know the volume of material in the Earth's crust and mantle, but before we move on it's also worthwhile to note that the Earth's crust and mantle have several Biblical synonyms.
Calculating the mass of the Earth takes circular reasoning and an assumption based on circumstantial evidence. It falls apart when you try to prove that there's no open space inside the Earth.
If you use circular reasoning to induce a rationalization of the premise that there's no hell, but there is a hell, and then you code your rationale as math, does hell disappear?
I had a tweet that asked the question: Why is the interior of the Earth hot? This started a conversation that revealed what we really know about the interior of the Earth. It started like this: