What force exists between all bodies, regardless of size?

Mutual gravitation is a fundamental force that exists between all bodies with mass, regardless of their size. This force is described by Newton's law of universal gravitation, which states that every point mass attracts every other point mass in the universe with a force that is directly proportional to the product of their masses and inversely proportional to the square of the distance between their centers. This means that even the smallest particles and the largest celestial bodies experience gravitational attraction.

In contrast, the electromagnetic force operates between charged particles and is not applicable to bodies without a charge. The strong nuclear force, which holds the components of atomic nuclei together, acts at very short ranges and does not affect bodies at larger scales. Frictional force is a force that arises between surfaces in contact and depends on the characteristics of those surfaces, making it not universal in the same way gravitational force is.

Therefore, mutual gravitation is the only force that universally applies to all masses, highlighting its significance in the understanding of both terrestrial and astronomical phenomena.