Cosmic Web

4-31-2024 — Written by Kevin Jie

Space can be observed on 5 levels, these levels are: planets, star systems, galaxies, galaxy clusters, and the cosmos.

From our position in the universe, these 5 levels become: Earth, the solar system, the Milky Way galaxy, the Local Group, and the cosmos.

These so-called “5 levels” are what Astron refers to as the 5 Visions of Space.

Although the first 4 visions are relatively self-explanatory, the last vision, the cosmos, is so incomprehensibly large that there is almost no definition for it.

Really, the cosmos is just “everything else”.

However, the cosmos can be partially defined, even though it itself spans indefinitely in all directions.

Well is that it?

The cosmos is the structure of the observable universe in its entirety?

Well, it isn’t that simple.

Defining the cosmos itself is another matter for another time, but the structure of the cosmos is far more than just galaxies.

If the cosmos is a web, and the galaxies are the strings, then what are the gaps?

Believe it or not, these do have names, and can be defined.

These are called galactic voids, massive gaps in space that lie between the connections of the cosmic web.

Galactic voids can span anywhere from 10 to 100 megaparsecs, or around 32.6 to 326 million lightyears.

These voids aren’t actually complete emptiness.

In these voids lie sparse rogue galaxies and wandering blackholes.

The cosmos is an intertwining structure composed of galaxies.

Each galaxy is chained together by one another through gravity

This explains why more populated regions have galaxies that are closer together.

Larger and more densely populated regions are called galaxy clusters, ours in specific is the Local Group.

Smaller less-dense areas on the other hand, are barely held together; some even losing galaxies as they escape the group’s gravitational pull.

These wandering celestial structures are called rogue galaxies; lost in space as they float in one direction until influenced by something.

These smaller groups and wandering bodies act as the bridges between larger groups.

Upon viewing the cosmos on a larger scale, we can see that the larger groups – connected by smaller ones – create a web-like pattern across space.

This web-like pattern is a well-ordered whole and is what we call the cosmos.

Now that we have the basic understanding of the cosmic structure, we can further define a few terms.

Galaxy superclusters are massive collections of galaxies that – similarly to galaxy clusters – are held together by gravity.

Something you may notice if you have ever observed a depiction of the cosmic web, there are splotches of faint undefined gas-like volumes of space that appear near galaxies.

These volumes of space, or rather the volume, is called the intergalactic medium, absurdly hot areas of space, made up of plasma and other gasses.

In fact, strands of the intergalactic medium are so hot that they can reach upwards of millions of degrees.

Furthermore, NASA states, “Much of the Intergalactic Medium is made up of hydrogen and helium,” remnants from the big bang.

However, over the time of its existence, much heavier elements, like silicon and sulfur, have been added due to supernovae across the universe.

Prior to talking about the voids of the cosmos, we mentioned that galaxy clusters are connected by other galactic structures that stand in between each nearby cluster, forming the strings of the cosmic web.

These connecting strings are referred to as galactic walls.

All together, this forms the complete general understanding of the cosmic web on a universal scale.

With this knowledge, much of the video below can be explained.

This video actually comes from NASA’s own depiction and explanation of the cosmic structure in detail.

Original Astron Document:

Space: Cosmic Web