Two stones do not visibly come closer to each other due to their mutual gravitational attraction because the immense gravitational pull of Earth completely overshadows their tiny forces. While gravitational force exists between any two objects with mass, the strength of this force is directly proportional to their masses and inversely proportional to the square of the distance between them.
The Dominance of Earth's Gravity
When two stones are placed on Earth, they are both subject to Earth's overwhelming gravitational force. The Earth is astronomically more massive than any two stones placed upon it.
- Mass Disparity: The Earth's mass is approximately 5.972 × 10^24 kilograms. In contrast, a typical stone might weigh only a few grams to a few kilograms. This colossal difference in mass means that the gravitational force exerted by the Earth on each stone is billions of times stronger than the minuscule gravitational force the two stones exert on each other.
- Overpowered Attraction: As a result, the primary gravitational pull experienced by each stone is towards the center of the Earth. The almost immeasurable attraction between the two stones is entirely masked and practically unobservable. It's like trying to feel the gentle breeze from a butterfly's wings while standing in a hurricane – the hurricane's force completely overpowers any sensation from the butterfly. The stones are effectively pulled to Earth rather than towards each other.
Conditions for Observable Mutual Attraction
For two objects, such as stones, to visibly pull each other closer due to gravity, very specific and highly controlled conditions would be required. These conditions are generally not found in our everyday environment:
- Total Isolation from Massive Objects: They would need to be in a vacuum, far away from the gravitational influence of any other significantly massive celestial bodies (like planets, moons, or stars). In such an isolated scenario, the weak gravitational force between them would be the dominant force, allowing them to slowly accelerate towards each other.
- Absence of Other Forces: There should be no other significant forces at play, such as air resistance, friction with a surface, or electromagnetic forces, that could prevent their subtle movement.
In the vastness of the universe, it's practically impossible to find a scenario where two small objects are totally isolated from any massive object, which is why we don't observe everyday objects "gravitating" towards each other on Earth. The gravitational force between them is real, but its effect is negligible compared to the Earth's pull.
