Gravity vs dark energy: what ensures the existence of the Universe

© Illustration RIA Novosti . Alina Planinarenje UniverseGravity vs dark energy: what ensures the existence of the Universe© Illustration RIA Novosti . Alina Polyanina

Dark energy is one of the phenomena of the Universe, the existence of which became known twenty years ago, but scientists to this day know her nature, not so much.

When Einstein in the early twentieth century deduced the gravity equation, it is assumed that there must be some force which will counteract the attraction of objects to each other. At that time scientists believed that our universe is static. But gravity acts in such a way that all objects with mass are attracted to each other. Therefore, the universe is not «shapeways,» there must be another force opposing gravity. Einstein introduced the equation the constant — cosmological constant, which was supposed to balance the gravity. But from the equality obtained showed that the universe is not static, but expanding, which was contrary to the existing theory. Scientist called the constant his great mistake, but it was a great prophecy.

In the late 1990-ies it was found that in remote galaxies, supernovae have brightness less than that which possessed, according to the earlier measurements. That is, the distance to these galaxies was greater than the distance calculated by the old formula: D=2R/2sin(α/2), where D is the distance to the star, R is the radius of earth’s orbit, α — the angle that would be visible to the average radius of earth’s orbit from the center of mass of a star.

The researchers concluded that the universe is not just expanding, but accelerating. Then these observations were experimentally confirmed by measuring the «irregularity» of the background radiation (a remnant energy of the Big Bang) and observing the formation of clusters of galaxies.

In addition to the impact on the expansion of the Universe, about dark energy is known very little. It shapes our world by 68%, has a low density, homogeneous and does not interact (at least, so that it was noticeable) with ordinary matter, except for gravity.

The nature of dark energy is difficult to determine because it is too different from the usual phenomena. The fact that in physics in the description of processes is important, not the value of the energy and its change. For example, when a potential difference occurs, the voltage (the electrons move from one point to another), and when changing the temperature we can determine exactly how many degrees the body is heated or cooled.

The exception to this is gravity — it has a constant energy, and not the difference in the values of the latter. The phenomenal field that affect the rate of expansion of the Universe, was called the vacuum energy, or dark energy. The field «spilled» over the entire space and has everywhere the same density. The presence of errors in cosmological observations leaves room to assume the existence of a weak dynamics of the vacuum energy.

«The fact that our experience of research of the Universe is negligible compared to the time of her life. For example, we photograph a large old oak tree every day for several months and do not notice any changes. On the basis of the experiment we conclude that the plant over time did not change. But probably our camera simply can’t detect minor changes, besides the time of the experiment too little? It is reasonable to assume that the constancy of dark energy is only apparent, and in fact we are seeing a dynamic field, only evolyutsioniruet it very very slowly. Therefore, final conclusions about the properties and nature of dark energy to do while early», — says Dmitry Gorbunov, associate Professor of the Department of fundamental interactions and cosmology the Moscow Physical-technical Institute.

But if the universe is expanding, why our senses do not feel? The fact that large concentrations of matter (e.g., galaxies) represent the gravitational system. And there’s a certain balance between the action of dark energy and gravity, through which such systems remain stable. And run the Universe is realized through the expansion of interstellar space.