Many different things can cause similar movements, you could detect something pulling those atoms in 1 direction, and something else pushing them back at the edge of the pebble which is closest to earths center of gravity. But you would not know what is causing that pull, only from where it is coming and how strong it is.
Many different things can cause similar movements, you could detect something pulling those atoms in 1 direction, and something else pushing them back at the edge of the pebble which is closest to earths center of gravity. But you would not know what is causing that pull, only from where it is coming and how strong it is.