Still a lot of mystery about gravity.
A guy I knew made top-of-the-line gravity meters. He was hired by the Air Force to try to determine if there was such a thing as “negative” gravity which was pushing mass farther away.
Their long-range missiles weren’t tracking properly, in spite of taking into account the varying mass of the earth going across various terrain.
He told me his work was inconclusive. He figured they just didn’t have accurate info on the various land masses. But he also kept an open mind about “anti-gravity” forces.