I’m a hypothetical billionaire, so let’s discuss financing this project and the chances of success, what we’ll need to get it done, and so forth. Theoretically, it would seem possible.
At the south pole the earth is 12,715 and a half miles in diameter, or about 7900 miles to the center, but at the equator the diameter is 12,756.32 kilometers or 7,926.41 miles to the center. The earth is thicker at the equator and it would take a deeper hole to drill from there. We can make a drill 12.7 miles shorter if we drill from Antarctica. So let’s start drilling there.
From Antarctica, our drill will need to be 3,950.5 miles long to reach the center of the Earth. That’s 300 miles longer than the distance between New York and Paris.
To build a drill like that we’ll have to use a modular design. We’ll start with a shorter drill bit and keep making it longer as we drill deeper until it reaches 3,950.5 miles long.
The drill would need to be really thick and made of some really strong stuff to get through granite and just generally tough layers of rock. A drill tip with diamond heads is probably the way to go. As we drill down, the bit will get dull from time to time and we’ll have to pull the whole drill bit out to replace the head. That might have to be done several times a day.
Eventually, at some depth or other, you’re going to encounter molten rock. In the core itself is molten iron. Your drill bit will melt. All that trouble for nothing.
It doesn’t sound practical to drill to the center-most point of the earth by drilling from anywhere.