The end of the expansion of the universe would soon be

In 1998, researchers discovered, through two parallel studies, that SN Ia-type supernovae moved faster and faster away from each other. Those supernovaquestions of binary systems containing a white dwarfconsidered as a landmark in cosmologyalso called standard candlesbecause their brightness remains constant over time. However, as the researchers assessed the distance that separated them as a function of time, they observed that it increased more and faster as a function of time! We already knew at that time thatUniverse was about to expand, but the model of it big bang assumed a slowdown of this expansion: observations showed the opposite.

Dark energy of unknown origin fills more than 70% of our universe

The only explanation found on this phenomenon involved the presence of one pressure negative caused by an unknown substance. Named ” dark energy “, Calculations have since shown that it fills more than 70% of the energy content of our universe without us being able to identify it. Undiscoverable despite numerous attempts, several theories have nonetheless attempted to model it. The most common model today is standard cosmological modelwhich presupposes constant acceleration and depends on cosmologically constant Λ, which represents vacuum energy. In this case, the acceleration is constant, so the expansion will continue indefinitely. But let’s look at another model, lesser known: it assumes a dynamic dark energy, that is, variable over time.

More precisely, dark energy would be like a substance determined by a scalar field, called quintessence. Each point in space is associated with a value of this quintessence V (Φ), which depends on the energy density and fabric which surrounds it. It then varies over time, and is thus against the theory that associates dark energy with cosmologically constant. Her wavelength would be in the order of magnitude of the universe, giving it almost zero kinetic energy. Since the pressure associated with the quintessence depends on the ratio of kinetic energy to potential energythis is negative, therefore coherent with a repulsive energy.

Acceleration would turn into deceleration within a few million years

According to this model, the quintessence can interact with ordinary matter when it is in large quantities, such as star system, or even larger, a galaxy. Right at the beginning of the universe, when it was still compact, the quintessence and matter would thus have interacted strongly and created a kind of acceleration boom. Like stars moving away, the fabric density decreases to become almost a constant, hence also the interaction with the quintessence.

In a study published in the journal Proceedings of the National Academy of Sciences, a group of cosmologists explored the idea of ​​quintessence. And their model predicts several changes for the expansion of the universe: First, its acceleration will slow down and stop soon, so instead of expanding the universe, it will contract little by little. Their calculations assume a gradual increase in kinetic energy and a parallel decrease in potential energy: hence the evolution towards a positive pressure which tends to contract the universe instead of stretching it: ” as the positive potential energy density decreases and the kinetic energy density exceeds it, the current phase of accelerated expansion will end and slip over into a period of decelerated expansion. So, when the scalar field continues to scale down the potential, the potential energy density will become negative enough that the total energy density and thus the parameter for Hubble H

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