What Sieben was mentioning with the cone to the center of the earth and expanding infinitely into space is called the Ad Coelum Doctrine.
I would recommend reading the article “Law, Property Rights, And Air Pollution” by Rothbard (specifically the Technological Unit section):
And also “The Privatization of Roads And Highways” by Walter Block. Chapter 14 covers Ad Coelum, and building bridges over, and tunnels under property, and elsewhere in the book he covers the topic of easements:
http://mises.org/resources/4084/The-Privatization-of-Roads-and-Highways
There is also this topic from the boards entitled “Homesteading The Sea”:
https://forum.freecapitalists.org/t/homesteading-the-sea/4206
I would also point towards Kinsella’s articles on criticizing the concept of “mixing your labor” meaning you own a given piece of property, and instead argues for first use has the best claim. Here is one I found quickly: