What is dark matter proposed to do in the universe?

Dark matter is a significant concept in astrophysics, and it is proposed to have a crucial role in providing the gravitational framework necessary to hold galaxies and galaxy clusters together. The presence of dark matter helps to explain the observed rotational speeds of galaxies, which cannot be accounted for by the visible matter alone. This suggests that there is a substantial amount of unseen mass exerting gravitational effects, thus maintaining the structure of the universe on a large scale.

This leads to the understanding that dark matter is not directly observable, as it does not emit, absorb, or reflect light in a way that can be detected using traditional telescopes. Instead, its influence is inferred from gravitational interactions. Without the presence of dark matter, the gravitational pull necessary to keep galaxies intact would be insufficient, leading to the prediction that they would not form or have the structure we observe today.