"This ultimately led [Einstein] to the realisation that gravity is best described and understood not as a physical external force like the other forces of nature but rather as a manifestation of the geometry and curvature of space-timeitself." This is in the introduction of the paper you shared...
1) it still somehow works like other fundamental forces since it derives from asking invariance under a local symmetry group
2) it is different from other forces since the symmetry group associated to it is directly symmetries of space-time (rather than some internal U(1) vector bundle like maxwell or SU(3) nuclear strong force)
3) in weak fields like on earth it mostly reduces to a conservative force driven by a gravitation potential (what you experience while climbing a mountain)
3 bis) like (mostly) anything in physics there is a duality i.e. there are regimes where you can consider it as a force, and there are regimes where you cant.
read the textbook, i know it's a 1000 pages but it's a great introduction :)
Give the commentor some credit -- I doubt they'd link a paper they are not familiar with.
Also in the paper:
"In a certain sense the main effect of curvature (or gravity) is that initially paralleltrajectories of freely falling non-interacting particles(dust, pebbles,. . . ) do not remainparallel, i.e. that gravity is an attractive force that has the tendency to focus matter."
Maybe don't immediately look for ways to discredit someone's contribution to the discourse without examining all of the content they have shared?
As the parent comment says, everything in physics depends on how you observe ("... best described").
Like Sean Carroll said in the Veritassium video about the "many worlds" [1], there's no such such thing as "pressure", it is just the interaction of fluid molecules. For practical purposes though, it is best described as a scalar called "pressure".
> best described and understood not as a physical external force
"best described as not a force" is not the same statement as "is not a force".
In physics and mathematics there can be multiple different, complementarity descriptions of the same thing. In fact, if you can reach the same result by two very different routes that seems to make it more robust.
