Which factor is responsible for the formation of the solar system?

Charge refers to the electromagnetic force that affects particles based on their electrical properties. While charge influences various phenomena in the universe, it does not drive the large-scale dynamics necessary for the formation of celestial bodies. The initial collapse of the solar nebula into a solar system is primarily governed by gravitational forces rather than electromagnetic interactions.

Friction is a force that resists the relative motion of two surfaces in contact. In the context of the solar system formation, friction among particles within the protoplanetary disk can play a role in slowing down and aiding the accretion process, but it is not the driving force behind the initial formation of the solar system. Without gravity, friction would have little effect on the overall structure and dynamics of the forming system.

Heat is a form of energy associated with the motion of particles and can influence the physical state of matter. While heat generated from gravitational compression and other processes affects the conditions within the solar nebula, it is not the primary factor that leads to the formation of the solar system. Gravity is the essential force that brings together the materials to form celestial bodies.