First time I knew about concave earth, it was only about one year ago (after 58 years of life thinking convex heliocentric, moon landings, etc..I met flat earth with 56 yo). At first I thought I would be very easy to debunk (just one reason is enough...if strong enough). But each time I tryed to find arguments to debunk concave, I found myself debunking all other models (and met geo convex in 2014 with the principle), specialy the convex heliocentric mainstream that have a motion for earth of about 1 million km per hour in 7 directions, and a misterious dark matter, much more misterious than ether. By October 2014, I already had put dark matter in garbadge and elected ether.
I must confess that the great work of LSC (Steven Christopher*) was an important factor for electing ether. But ether is present in convex geocentric and flat model (maybe?) too.
* Hollow earth of Edmund Halley, observations of Brahe, experiments by Ulysses Grant Morrow and Cyrus Teed, (except electric knowledge of Nikola Tesla that never admited gravity and relativity as mainstream science still describe it), geometry of Mostafa Abdelkader, the intuition of Peter Bender (a german pilot), the article of Karl E. Neupert, the book of Johannes Lang and the work of Rolf Kepler are nothing compared with the work and research of Steven Joseph Christopher, That is amazing!