宇宙网（Cosmic Web）是一个包含气体、星系和缠绕在宇宙空隙周围的相互连接的丝状物和团状物的网络，横跨数百万光年，代表了宇宙的最大尺度。 天体物理学家在20世纪60年代就已经预测到了，20世纪80年代的计算机模型为这个庞大的网络提供了一个直观的表现。
The cosmic web is a vast, intricate network of matter that makes up the large-scale structure of the universe. It consists of interconnected filaments of dark matter and gas, along with galaxies and clusters of galaxies. The cosmic web forms the skeleton of the cosmos, linking dense regions of matter with vast, empty voids in between.
The formation of the cosmic web and large-scale structures can be understood through the following points:
1. **Dark Matter**: Dark matter plays a crucial role in the formation of the cosmic web. It provides the gravitational framework that attracts ordinary matter (baryonic matter) to form galaxies and clusters. Dark matter clumps under its own gravity, forming the initial structures in the universe.
2. **Cosmic Inflation**: In the early universe, during the period of cosmic inflation, tiny quantum fluctuations were stretched to macroscopic scales. These fluctuations seeded the density variations in the universe.
3. **Gravitational Attraction**: Over billions of years, regions with slightly higher density began to attract more matter due to gravity, leading to the growth of structures. This process, known as hierarchical clustering, results in smaller structures merging to form larger ones, like galaxies forming clusters and superclusters.
4. **Gas Dynamics**: Along the filaments of the cosmic web, gas flows towards denser regions. This process leads to the formation of galaxies along these filaments, which are then connected by the web.
5. **Observations and Simulations**: Observations, such as those from large-scale galaxy surveys and the Cosmic Microwave Background (CMB) radiation, along with computer simulations, support the existence and structure of the cosmic web. These tools show how galaxies are not randomly distributed but are organized into a web-like pattern.
In summary, the cosmic web is the large-scale structure of the universe, formed by dark matter and ordinary matter through gravitational interactions and the initial conditions set by cosmic inflation. It explains the distribution and arrangement of galaxies, clusters, and voids, providing a comprehensive picture of the universe's structure.
