Large-scale structure of the universe

The distribution of galaxies and matter across the cosmos, organized into a cosmic web of filaments, clusters, and vast voids.

Cosmic inflation: A hypothesized early period of rapid expansion that stretched quantum fluctuations to cosmic scales. Inflation supplied the primordial fluctuations that later grew into structure.
Galaxy cluster: A gravitationally bound system containing hundreds to thousands of galaxies, hot gas, and dark matter. Clusters mark dense nodes where cosmic filaments meet.
Galaxy redshift survey: An astronomical survey that measures galaxy positions and redshifts to map their three-dimensional distribution. Redshift surveys expose the filaments, clusters, and voids across large volumes.
Cold dark matter: A dark-matter model in which particles moved slowly compared with light when cosmic structures began forming. It predicts abundant small-scale structure that shapes the web's detailed hierarchy.
Cosmic microwave background: The relic radiation released when the early universe became transparent, carrying a map of tiny temperature variations. Its temperature variations reveal the seeds from which structure grew.
Galaxy filament: An elongated concentration of galaxies and dark matter connecting denser regions of the cosmic web. Filaments form the web's connecting strands.
Weak gravitational lensing: Small coherent distortions in background galaxy images caused by intervening gravitational mass. Lensing maps the web's total mass, including invisible dark matter.
Warm dark matter: A dark-matter model with faster early particle motion that suppresses the formation of small structures. It reduces small-scale clumping relative to the standard cold-dark-matter picture.
Gravitational instability: The growth of density variations as gravity draws matter toward regions already denser than their surroundings. It amplifies primordial contrasts into sheets, filaments, and bound systems.
Cosmic void: A large region of space with substantially fewer galaxies and less matter than surrounding regions. Voids define the emptier spaces between filaments and clusters.

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