4 ms·

Hallow Earth, perhaps with dinosaurs still living there is, of course, BS. However, it may not be all barren in there either, e.g. this report from 2006 talking

by Jun8 2y ago

Hallow Earth, perhaps with dinosaurs still living there is, of course, BS. However, it may not be all barren in there either, e.g. this report from 2006 talking about bacteria nearly 2 miles in: https://www.princeton.edu/news/2006/10/20/two-miles-underground-strange-bacteria-are-found-thriving https://www.princeton.edu/news/2006/10/20/two-miles-undergro.... So, as a Friday afternoon thought, one can hypothesize the existence of large-ish (~hundreds of meters) empty cavities within the mantle with some simple animal life (worms, insects?), which doesn't sound totally off the rails to me. I wonder if our current seismic analysis technology can detect such cavities (chatGPT says waves to propel core have wavelengths on the order of kilometers).

andrewflnr 2y ago
No, "within the mantle" is definitely off the rails. It's really hot down there, way hotter than cooking temperatures. A few highly specialized microbes can survive conditions like that, but not animals. Also the pressure is high enough that rock acts like liquid. Large cavities cannot survive. I think this started to be a problem even for the Kola borehole, the walls of the hole just started squishing in.
- drjasonharrison 2y ago
  The Kora Borehole got to 12,262 metres deep, and was stopped due to a lack of funds.[1] """ Drilling penetrated about a third of the way through the Baltic Shield of the continental crust, estimated to be around 35 kilometres (22 mi) deep, reaching Archean rocks at the bottom.[13] Numerous unexpected geophysical discoveries were made: During the drilling process, the expected basaltic layers at 7 kilometres (4.3 mi) down were never found, nor were basaltic layers at any depth.[14] There were instead more granites, deeper than predicted. The prediction of a transition at 7 kilometres was based on seismic waves indicating discontinuity, which could have been caused by a transition between rocks, or a metamorphic transition in the granite itself.[14] Water pooled 3–6 kilometres (1.9–3.7 mi) below the surface,[14][15] having percolated up through the granite until it reached a layer of impermeable rock.[16][17] This water did not naturally vaporize at any depth in the borehole.[15] The drilling mud that flowed out of the hole was described as "boiling" with an unexpected level of hydrogen gas.[18] Microscopic plankton fossils were found 6 kilometres (3.7 mi) below the surface.[1] """ [1] https://en.wikipedia.org/wiki/Kola_Superdeep_Borehole https://en.wikipedia.org/wiki/Kola_Superdeep_Borehole

by Jun8 2y ago

andrewflnr 2y ago

No, "within the mantle" is definitely off the rails. It's really hot down there, way hotter than cooking temperatures. A few highly specialized microbes can survive conditions like that, but not animals. Also the pressure is high enough that rock acts like liquid. Large cavities cannot survive. I think this started to be a problem even for the Kola borehole, the walls of the hole just started squishing in.

drjasonharrison 2y ago
The Kora Borehole got to 12,262 metres deep, and was stopped due to a lack of funds.[1] """ Drilling penetrated about a third of the way through the Baltic Shield of the continental crust, estimated to be around 35 kilometres (22 mi) deep, reaching Archean rocks at the bottom.[13] Numerous unexpected geophysical discoveries were made: During the drilling process, the expected basaltic layers at 7 kilometres (4.3 mi) down were never found, nor were basaltic layers at any depth.[14] There were instead more granites, deeper than predicted. The prediction of a transition at 7 kilometres was based on seismic waves indicating discontinuity, which could have been caused by a transition between rocks, or a metamorphic transition in the granite itself.[14] Water pooled 3–6 kilometres (1.9–3.7 mi) below the surface,[14][15] having percolated up through the granite until it reached a layer of impermeable rock.[16][17] This water did not naturally vaporize at any depth in the borehole.[15] The drilling mud that flowed out of the hole was described as "boiling" with an unexpected level of hydrogen gas.[18] Microscopic plankton fossils were found 6 kilometres (3.7 mi) below the surface.[1] """ [1] https://en.wikipedia.org/wiki/Kola_Superdeep_Borehole https://en.wikipedia.org/wiki/Kola_Superdeep_Borehole