New dark energy model

Try imagining for a moment that the entire universe freezes. According to a new dark energy model, that happened about 11.5 billion years ago, when the universe was about the size of a quarter today.

This model, published online May 6 in Physical Review D, was developed by researcher Sourish Dutta and physics professor Robert Cherrer at Vanderbilt University, in collaboration with physics professor Stephen Hsu and graduate student David Reeb at the University of Oregon.

The process of transforming the universe - similar to freezing - is a separate aspect of the latest attempt to understand dark energy - the mysterious sound that cosmologists think makes up 70% of all. energy and matter in the universe and are expanding the universe at a faster rate than ever before.

Another characteristic that distinguishes the new model is that it gives a predictable test of the expansion rate of the universe. In addition, small explosions generated by the largest collision between dark energy-stimulating particles, and these stimuli, can appear as strange subatomic particles never seen before.

Scherrer said: 'One of the drawbacks of many dark energy explanations is that it is very difficult to test them. We design models that can interact with ordinary matter and have observable results'.

This model links dark energy to vacuum energy. Like some existing theories, this model assumes that space itself is a source of energy to expand the universe. For many years, scientists believed that the energy of empty space was zero. But the discovery of quantum physics has changed this view. According to quantum theory, vacuum is full of pairs of particles that exist and disappear so quickly that it cannot be detected.

The subatomic activity is a reasonable source for dark energy because they both spread the same space. This distribution is consistent with the evidence that the average density of dark energy does not change when the universe expands. This property is in contrast to ordinary matter and energy, because as the universe expands, the energy and matter are normally diluted.

The ultimate fate of the universe depends on the true nature of dark energy.Based on its properties, the universe could be torn apart, or the current expansion reversed into contraction, or any other possibility.(Photo: NASA / CXC / M. Weiss)

The above theory is one of the theories that dark energy belongs to a completely new field called quintessence. Quintessence is similar to other basic fields including gravity and electromagnetism, but there are some special properties. For example, the intensity of this field is the same throughout the universe.Another important feature is that it plays an anti-gravitational role that makes objects move away from each other instead of pulling together like gravity.
In its simplest form, the intensity of the quintessence field does not change over time. In this case it acts as a cosmological constant, a term Albert Eisntein adds to the theory of relativity to keep the universe from contracting because of gravity. When the evidence shows that the universe is expanding, Einstein abandoned this term, because the expanding universe is the solution to the relative equation. Then, in the late 1990s, supernova studies (intense light explosions that illuminated the entire galaxy contained millions of stars) indicating that the universe was not only expanding, but also that the speed of expansion was faster, not slow down as scientists predicted. This confuses cosmologists, who argue that gravity is the only distance force between astronomical objects. So they don't know what's pushing things apart. The simplest way to explain this strange phenomenon is to return to Einstein's cosmological constant with its anti-gravitational properties. Unfortunately, this explanation has some serious drawbacks, so physicists have tried to find other anti-gravity agents. These agents often need quintessence or even more exotic fields. All of these fields have not been discovered in nature, but their composition shows that they do not interact much with ordinary matter and radiation.

One of the consequences of allowing quintessence to interact with ordinary matter is the ability of the school to undergo a transition - freeze - when the cosmic temperature drops to a level equivalent to 2.2 billion years later. Big Bang. Therefore, the energy density of the quintessence field will remain at a relatively high level until this transition, when it suddenly drops to a significantly lower level. The conversion process can release part of the dark energy inside the field in the form of dark radiation. According to this model, dark radiation differs from light, radio waves, microwaves and other common types of radiation: It is completely undetectable by any device. However, nature provides a detection method. According to Einstein's theory of relativity, gravity is generated by the distribution of energy and momentum. So changing energy and momentum due to dark radiation can affect the gravitational field of the universe, which slows the expansion of the universe.

In about 10 years, astronomical surveys charting the expansion of the universe by measuring the luminosity of the most distant supernovae will probably be able to detect the slowdown in the rate of expansion at which tissue This picture predicts. At the same time, new molecular accelerators, such as the Large Hadron Collider in Switzerland, can generate energy large enough to stimulate quintessence fields and these stimuli can appear as exotic particles. new.

Research funded by the US Department of Energy.

References:
Sourish Dutta, Emmanuel N. Saridakis, and Robert J. Scherrer.Dark energy from a quintessence (phantom) field rolling near a potential minimum (maximum).Physical Review D, 2009;79 (10): 103005 DOI: 10.1103 / PhysRevD.79.103005