Is it not amazing to know that we can know, why does linear acceleration of galaxies occur by studying linear acceleration of whirlpools in water current?
Please, see
"A new alternative theory of gravity where gravity is particles behaving as a fluid forming two types of swirls Annular swirls and oval swirls".
https://www.researchgate.net/figure/Figure-3-Conceptual-depict-shows-the-entire-curvature-revolves-together-around-center_fig3_330763968