Final answer:
Observational evidence for dark matter includes the rotational speeds of stars in galaxies, gravitational lensing effects, and cosmic microwave background radiation fluctuations, all suggesting the presence of significant unseen mass influencing galactic structures and the universe's large-scale framework.
Step-by-step explanation:
The observational evidence in favor of there being a great deal of dark matter in the universe includes several compelling lines of inquiry and discovery:
- Studies of the motion of stars within galaxies and of galaxies within clusters have shown that there's more mass than what is visible in the form of stars and gas. The rotational speeds of stars in galaxies are too high to be accounted for by just the visible matter, suggesting the presence of a significant amount of unseen matter.
- Gravitational lensing, a phenomenon predicted by the general theory of relativity, indicates the presence of dark matter through the bending of light from distant sources, revealing mass not accounted for by visible objects.
- Measurements of the cosmic microwave background radiation (CMB) also support the presence of dark matter. Fluctuations in the CMB indicate the distribution of mass in the early universe, which includes dark matter.
The sum of these observations supports the hypothesis that dark matter is a major component of the universe, influencing the structure and evolution of galaxies and the large-scale structure of the cosmos.