The presence of dark matter is believed to extend throughout the universe, not just within and around galaxies. Observational evidence, such as the rotation curves of galaxies, gravitational lensing, and the large-scale structure of the universe, strongly suggests the existence of dark matter.
Dark matter is a form of matter that does not interact with light or other electromagnetic radiation, making it difficult to directly detect. Its presence is inferred from its gravitational effects on visible matter and light. According to current cosmological models, dark matter is thought to be a dominant component of the total matter content in the universe, comprising about 85% of the matter.
On galactic scales, dark matter plays a crucial role in explaining the observed motions of stars and gas within galaxies. The gravitational influence of dark matter helps to account for the observed high velocities of objects far from the galactic center, which cannot be explained by the visible matter alone. The distribution of dark matter is thought to extend beyond the visible extent of galaxies, forming a larger-scale halo-like structure.
Moreover, on larger scales, dark matter is believed to be an important component in the formation and evolution of the cosmic web, which consists of filaments and clusters of galaxies that span vast regions of the universe. The gravitational pull of dark matter helps drive the formation of structure in the early universe, leading to the clumping of matter and the subsequent formation of galaxies and galaxy clusters.
While dark matter is thought to be pervasive throughout the universe, its exact nature and properties remain unknown. Numerous experiments and observational efforts are underway to directly detect or indirectly infer the presence of dark matter particles and gain a deeper understanding of this mysterious component of the cosmos.