What Is the Cosmic Web?

The cosmic web is the universe's biggest known structure, dwarfing galaxies and clusters in size and complexity. It's a massive, complex network of interconnected filaments and low-density regions that spans the entire observable universe. Mostly made up of dark matter, these massive threads of galaxies and gases stretch over millions of light-years. Together, they create a cosmic tapestry that connects galaxy clusters and helps shape the universe on the grandest of scales.

In this article, you'll discover the different parts of the cosmic web. You'll find out how it formed and evolved, showing how small density fluctuations in the early universe, enhanced by gravity, led to this vast structure. You'll also gain insights into how the cosmic web plays into the galaxy's formation, dark matter's distribution, and the overall structure of the universe.

Dark Matter Filaments

Dark matter filaments are large, thread-like structures that make up a significant part of the cosmic web, linking galaxies and galaxy clusters. According to Philosophy of Cosmology, these filaments are thought to be leftovers from the initial quantum fluctuations of the early universe, which gravity has amplified over billions of years. Recent findings, based on 3D cosmological simulations and real data from the Sloan Digital Sky Survey, suggest that these massive structures might be the biggest spinning objects in the universe.

Modern techniques, such as gravitational lensing, have been instrumental in identifying and mapping these elusive structures. This process happens when the gravitational field of a massive object, such as a dark matter filament, warps the light from a galaxy in the background. Female scientists, such as Vera Rubin, and other experts in the field have made significant breakthroughs using these techniques, contributing to our understanding of the cosmic web.

Galaxy Superclusters

Galaxy superclusters are vast assemblies of smaller galaxy clusters and groups among the largest structures in the universe. According to Astronomy & Astrophysics*, *superclusters formed over billions of years by gravity and originated from small density variations after the Big Bang. These fluctuations grew to form galaxies, clusters, and superclusters, which are interconnected by filaments in the cosmic web. Superclusters impact galaxy distribution and motion, playing a stable and crucial role in shaping the cosmos.

Superclusters serve as nodes within the cosmic web, linked by filaments of dark matter and galaxies. These connections influence galaxy evolution, star formation, and the distribution of matter throughout the universe. One such supercluster is Laniakea.

Laniakea Supercluster

The Milky Way galaxy is part of the Laniakea supercluster, an enormous structure made up of about 100,000 galaxies spread across 520 million light-years. The discovery and mapping of Laniakea have been significant in enhancing our understanding of the cosmic web. This supercluster encompasses the Virgo Cluster, to which the Milky Way belongs, and defines the boundaries of our local cosmic neighborhood.

Laniakea's significance comes from its gravitational influence on the flow of galaxies in its region. Studying Laniakea helps astronomers understand the motion and distribution of galaxies, offering insights into the dynamics of space and the universe's evolution.

Gas Filaments and Intergalactic Space

Gas filaments are essential parts of the cosmic web, filled with huge amounts of gas and trace elements. Mostly made up of hydrogen from the Big Bang, these filaments contain over 60% of the universe's gas and help fuel areas where stars are formed, making them vital for galaxy formation.

These gas filaments are among the faintest structures in the universe, making them difficult to detect. However, advanced telescopes have captured images confirming their presence and significance. These filaments act like highways, funneling gas to galaxies and aiding star formation. The gas within them serves as a reservoir, supplying material for galaxies to grow and form stars. As galaxies use this gas, they evolve and shape the universe's structure.

The Cosmic Web of Galaxies and the Big Bang

The link between the cosmic web and the Big Bang theory is critical to understanding just how the universe's largest structure came to be. After the Big Bang, the early universe was a hot, dense mix of particles with quantum fluctuations that acted as seeds for future cosmic structures. According to a European Space Agency article, these fluctuations, influenced by dark matter, formed the gas filaments that shape the cosmic web of galaxies we see today. The CMB further reveals how these early fluctuations evolved into the complex structures of galaxies and clusters.

As the universe expanded and cooled, the cosmic microwave background (CMB) radiation provided a glimpse of the universe at 380,000 years old. The CMB reveals tiny temperature variations corresponding to density fluctuations. These fluctuations, under the influence of gravity, gradually coalesced, leading to the formation of galaxies and clusters. This evidence supports the Big Bang theory and helps us understand how matter is distributed throughout the universe.

The cosmic web forms through the interaction of dark matter and regular matter. Dark matter, due to its gravitational pull, creates a framework that guides the distribution and movement of regular matter. As normal matter cools and forms hydrogen atoms, it's pulled into the gravitational wells produced by dark matter, forming galaxies along the strands of the cosmic web.

Dark Energy and Expansion of the Universe

Dark energy is critical in how the universe expands and shapes the cosmic web. About 70% of the universe is governed by this enigmatic force, believed to drive the rapid expansion of space. NASA's Hubble Space Telescope has revealed that the universe's expansion rate increased about 7.5 billion years ago, and dark energy is credited for that change. This repulsive force pushes galaxies apart and significantly affects the universe's large-scale structure.

Dark energy's effects are most noticeable on cosmic scales, driving galaxies apart at increasing speeds. Unlike gravity, which pulls matter together, dark energy exerts a negative pressure, causing the universe to expand faster over time. Distant supernovae observations revealed unexpected dimness and distance, indicating the universe's accelerating expansion. This cosmic tug-of-war influences the universe's fate. Models suggest ongoing acceleration might lead to the "Big Rip," tearing apart galaxies, stars, and atoms.

From superclusters like Laniakea to gas filaments, each cosmic web component is vital for our understanding of the cosmos. By studying these structures, scientists and the world may gain insights into the universe's past, present, and future and unravel the mysteries of dark matter and energy and the ever-fascinating Big Bang.