Seven hundred million light years is practically nothing - this is the empty place in the observable universe. The Great Emptiness has puzzled scientists for almost 40 years, forcing them to put forward the most unusual hypotheses about its nature.
When you look up at the sky at night, it can seem as if the stars are infinitely scattered throughout space in a uniform manner. But it is known that this is not so. Stars are clustered in galaxies, and galaxies cluster together to form gravitationally bound clusters. In general, the situation is such that neighboring galaxies are located relatively close to each other (on a cosmic scale), and the void does not extend over very large areas of space.
However, there is one special case known as Bootes's Void. This is an incredible area of empty space, not observed anywhere else in the known universe.
This area was discovered in 1981 by astronomer Robert Kirchner and his team. Void Bootes is sometimes called the Great Void - it is a huge spherical region of space in which there are very few galaxies. It is located about 700 million light-years from Earth, in the direction of the constellation Bootes (hence the name). Initially, astronomers talked about their amazing discovery in the article "A million cubic megaparsec void in Bootes" (A million cubic megaparsec void in Bootes).
Pretty empty void
In diameter, this supervoid is 330 million light years, which, in turn, is equal to 0.27% of the diameter of the observable universe (93 billion light years across). The volume of this region is approximately 236 thousand cubic megaparsecs. In other words, it is the largest known void in the universe.
Void map Bootes / Richard Powell.
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Soon after the discovery of the Bootes void, astronomers began to notice how unique this area is. At first, they were able to find only eight galaxies in it, but further observations helped to find 60 galaxies in a huge space with a diameter of a quarter of a billion light years. According to astronomer Greg Aldering, if the Milky Way were in the center of the Bootes void, we would have learned about the existence of other galaxies only in the 60s of the XX century.
By comparison, our native Milky Way has about two dozen neighbors in a region of space just three million light years across. Considering that the average distance between galaxies in the Universe is several million light years, then in such a huge space as Bootes's entrance, with a similar density, there would be about 10 thousand galaxies.
Like soap bubbles
Naturally, scientists are eager to find out how such an anomalous region of space could have formed. Computer models suggest that smaller voids - which are much more common - formed after galaxies approached, as a result of gravitational interaction. Because of this, neighboring regions have become empty, and as this process intensifies, the areas become larger.
However, this does not explain the existence of the Bootes void. Not enough time has passed since the birth of the Universe for gravitational forces to “clear” a space of this scale.
Attempts to find an explanation have led to the development of a new theory, suggesting that supervoids are formed as a result of the merging of smaller voids. Aldring once noticed that galaxies in voids take on curious tubular shapes, and this seems to be an important clue. In addition, he suggested that Bootes's void was formed after the merging of smaller voids - similar to how soap bubbles merge into one large bubble. As for the "tubular" galaxies, then, most likely, these are remnants of boundaries between smaller voids.
The Dyson Sphere, built around a star to collect its energy, as imagined by the artist / J. Wong.
You can also assume an even more radical scenario, which has hardly been considered in the scientific literature. So, Bootes' void could have formed as a result of the expansion of the third type of civilization on the Kardashev scale. In the process of colonization, the "bubble" of civilization expands away from the native system of civilization, which obscures every star (and then every galaxy) in its path, covering it with a Dyson sphere. This could explain the fairly even spherical shape of the void. Considering that Bootes' void is located about 700 million light-years from Earth, and intelligent life in the Universe could have arisen about four billion years ago, such an ancient civilization had ample time to implement this amazing cosmological engineering. Yes, this is pure speculation, but,given the strangeness of the phenomenon itself, this hypothesis can be considered.
Scary and empty place
The nature of emptiness provides food for thought. Surely, visitors to this area would be, to put it mildly, overwhelmed by such isolation, given the extreme distances between galaxies, and the view of distant space that would appear "blacker than black."
Moreover, Bootes' entrance is probably the most "ideal" vacuum in space, the effects of which are also worth paying attention to. It would rarely contain not only stones and dust, but also various kinds of particles. For the interaction of particles in this huge void, epochs can go away, if at all possible there.
Map of galactic voids in the observable Universe / Andrew Z. Colvin.
The extremely low density of matter in this region of space means that when some kind of "structure" - neutrinos, for example - gets into it, on the one hand, it will look exactly the same when it comes out hundreds of millions of years later. The same goes for photons. Particles of matter with a much greater mass than neutrinos and photons will naturally be attracted to the edges of the void. Because of this property of preserving the state of the voids, Bootes can one day be regarded as an ideal time capsule.
Be that as it may, the discovery of super-void greatly influenced traditional cosmological thinking. Since then, astronomers have repeatedly revised their understanding of galaxy formation, given what is known about the highly uneven distribution of matter in the universe.
After all, Bootes' entrance is another humble reminder of the vastness of space. The universe we see is unimaginably huge for our understanding, and our place in it is surprisingly small and insignificant - a microscopic flash in gigantic space. But no matter how lonely we may seem to ourselves on our little blue dot, in any case, we have the opportunity to contemplate the starry landscape when we turn our eyes to heaven.
Vladimir Guillen