Is the universe being torn apart? The culprit may be the empty vacuum!

Could the empty vacuum be the culprit behind the expansion of the universe?

A vacuum filled with dark energy may be causing the universe to expand

This is an artistic rendering of the cosmic web. Its structure resembles a giant spider web, with a large number of purple filaments and some orange filaments dotted on a black background. (Image source: Volker Springel et al., from the Max Planck Institute for Astrophysics)

Vast tracts of almost completely empty space that make up most of the universe may be causing its expansion to accelerate, new research suggests. That means these vast tracts of empty space may explain the existence of dark energy, a mysterious force tearing the universe apart.

Welcome to the world of vacuum

If all the matter in the solar system and the Milky Way is removed, an interesting phenomenon will be discovered: the cosmic web, the largest structure in nature, on this scale, even an entire galaxy is just a point of light structure. Astronomers call the long, thin ropes they observe filamentary structures, and the denser ones clustered structures. The space between them is almost entirely empty. These spaces are the huge cosmic vacuum, the smallest of which is 20 million light years long, and the largest space is more than 160 million light years.

Like the gaps in a spider's web, the vacuum occupies the vast majority of the volume of the universe, even though it is almost empty. In fact, aside from the cosmic web, which stretches to the end of the observable universe, the cosmic vacuum is the largest thing in the universe.

Energy of the Void

Astronomers first detected the cosmic vacuum in the late 1970s, but the result was ignored until then. Instead, astronomers and cosmologists focused on exploring the structure of matter in the visible part of the universe, such as galaxies and star clusters. Through these studies, astronomers discovered a surprise in the 1990s: dark energy.

Dark energy gets its name from the accelerating expansion of the observable universe, which means that the universe is not only expanding every day, but also expanding faster and faster.

Astronomers at this time had no idea why the universe's expansion was accelerating, except that it began about 5 billion years ago. Hence the term "dark energy" - a huge cosmological puzzle with a cool name.

What is the relationship between vacuum and dark energy? First, the effects of accelerated expansion are not felt inside star systems or galaxies, because the gravitational pull between matter is much stronger than it. For example, neither our solar system nor the Milky Way is getting bigger because of dark energy, but because the space between matter is almost completely vacuum, it is more susceptible to this expansion. Therefore, it is very necessary to study the properties of this accelerated expansion where the expansion effect is strongest.

A new research paper published by a team of theoretical physicists in Iran has taken this idea a step further. In this paper, which was pre-published on the database arXiv in July and finally published in the Monthly Notices of the Royal Astronomy: Letters, the authors argue that dark energy is not found in the vacuum, but that the vacuum causes the generation of dark energy.

In the Dark

How do these huge regions of vacuum cause the expansion of the universe to accelerate? According to the authors, the answer is not only because the vacuum exists, but also because the vacuum generates momentum.

The cosmic vacuum not only exists, but like all other large structures in the universe, it has grown from a relatively low starting point to its current size. Billions of years ago, all the matter in the universe was evenly distributed, with similar densities in different places. As time went by, areas with more matter began to attract more matter than areas with more evenly distributed matter. As more matter gathered, these areas generated stronger gravity and grew faster. Over billions of years, matter gathered to form galaxies, star groups, and star clusters.

As this structured matter is created, the vacuum region will grow. But rather than viewing it as a passive process, we can measure the growth of the vacuum by measuring the pressure it exerts on the surrounding matter. For example, as the vacuum region grows, the boundaries of galaxies will gradually become thinner and disappear, and all the vacuum will merge together. Over the next few billion years, the vacuum will dissolve the cosmic web, forcing all matter to be separated into clusters of vacuum hundreds of millions of light years long.

This pressure, like all other matter and energy in the Universe, can distort the vacuum of space and time. The distortion of space and time means that the vacuum expansion will push the boundaries of galaxies and cause them to separate.

The authors found that all large-scale vacuums in the universe together dissolve the cosmic web, causing the accelerated expansion of the universe. This accelerated expansion of the vacuum-driven force matches the current dark energy hypothesis.

Astronomers still need further research to prove this point. On the one hand, we need more vacuum measurements to better calculate the total pressure produced by the vacuum, and on the other hand, we need to know more about dark energy, especially whether its energy has changed over the past few billion years. In addition, there is an interesting point: Maybe dark energy is not produced by some external force or process in the universe but is just a byproduct of the normal evolution of the cosmic vacuum.

This article first appeared in the journal Life Sciences.

BY:Paul Sutter

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