Today we will talk about the void; by the meaning, we know that void means nothing or space but do you know that voids are not empty? They also have some galaxy clusters, and this is one of the most extensive parts of our observable universe, so what is a void? How void is created? And where we are? Let's find the answer to these questions one by one.
What is Void?
In physical cosmology, observations of large-scale structures suggest that galaxies cluster are around specific points in space and time. These points can be identified as low-density regions called Space voids. The mention of large-scale voids is essential for understanding galaxy formation. Voids located in high-density environments are more minor than voids situated in low-density spaces of the universe. Other voids include Supervoids, Huge-Void, Very Large Void, Giant Void, and Abell void. Galaxies form some kind of clusters (group), and these clusters arrange themselves as branches called filaments, all connected with some sort of force, and the gap between filaments are voids. These gaps are because of low density, So why do voids have lower density?
Reason Behind the difference in density
The universe's density is measured as the number of galaxies per unit volume. So why do voids have lesser density; to know the reason, we have to go to the past of our universe; the cause was at the beginning 13.7 billion years ago, everything started with the Big bang, the most giant blast from which everything was created after explosion everything was very hot or in the form of plasma with almost same density everywhere, and then some kind of wave generated called baryon acoustic oscillation which changed the density of our universe; Calculations show that one way to make such a big void would be to put a mass on the order of 200 million lightyears away from us with about 1/200th the density of ordinary hydrogen atoms. Another way is to have a supercluster 10 billion lightyears away with approximately 1/10th the density of regular hydrogen atoms. In the beginning, these gaps were not too big, but with time these gaps became huge, even more than a filament, and now these are known as Space voids.
When did we get aware of the void?
In 1970 scientists were doing Redshift surveys; in this survey, scientists wanted to know at what speed galaxies were getting far from each other with the expansion of the universe. In this, the wavelength of light from different objects helps predict the galaxy's location. In the survey, scientists found that galaxies are not distributed in a definite manner, some galaxies are close where some are very far, and in some places, galaxies are in the form of clusters. In 1978 Stephan Gregory and Laird A. Thompson published their research papers which gave us clues about the presence of the void.
Some most immense voids
In astronomy, voids are the space between filaments (the largest-scale structures in the universe), which contain very few or no galaxies. Voids typically have a diameter of 23 megaparsecs or more and roiling volumes of space that can be hundreds of times larger than the typical size of a supercluster. They are too huge but with the most diminutive galaxies, and there are many voids too. one of them is Bootes Void; this void is about 700 million lightyears far from our earth; its diameter is almost 330 million lightyears, and this void was found by an American astronomer Robert Kirshner in 1981, we had been located 60 galaxies in Bootes void, but we cannot say this indeed since it is too far. There is a possibility that many universes were destroyed in the time it took light to reach us. The fact is our galaxy is also located in a void. We are almost near the centre of a void.
Now we know that voids are not just space but huge lower density reason with few galaxies in them; they are between filaments, and filaments are the group of clusters and superclusters; we also found the answers to how is a void created and what is the reason of difference in density after this we had read some history of void and then, at last, we get aware of the size of void and two biggest voids one is Bootes and surprisingly our Milkyway is located in the second one.