What is the role of gravity in galaxy formation?

The role of gravity in galaxy formation is fundamental, as it essentially acts as the glue that draws matter together over time. Initially, the universe was filled with a nearly uniform distribution of gas and dark matter. Small fluctuations in this matter density allowed gravity to begin pulling together clumps of gas and dark matter. This process leads to the gradual accumulation and clumping of matter, leading to larger structures such as galaxies.

As gravity pulls these clumps together, they become denser and can collapse under their own weight, eventually forming stars and galaxies. The gravitational interactions between these clumps also help to coalesce them into larger systems. As such, the mechanism of gravity is critical in the evolutionary process of galaxies, shaping their structure and distribution across the cosmos.

In contrast, other options reference different aspects of gravity's role but do not directly address its central function in galaxy formation. For example, while gravity does play a role in stabilizing orbits within galaxies, the core question concerns the initial formation and organization of galaxies themselves.