In 1998, scientists discovered, through two parallel studies, that SN Ia . type supernovae They were moving away from each other faster and faster. these Supernovaissues Binary systems containing a white dwarfare landmarks in cosmologyalso called Standard candlesbecause they are brightness It remains stable over time. However, when the researchers evaluated their distance as a function of time, they noticed that it increased even more rapidly as a function of time! We already knew at the time that a filebeing It was expanding, but a model the great explosion This expansion is assumed to slow: observations have shown the opposite.
Dark energy of unknown origin occupies more than 70% of our universe
The only explanation that has been found for this phenomenon involves the presence of a the pressure Negative caused by an unknown substance. the name of the thing dark energy Calculations have since shown that it fills more than 70% of the energy content of our universe, without us being able to recognize it. It can’t be detected despite many attempts, yet many theories have tried to model it. The most commonly used model today is Standard Cosmic Modelwhich assumes a constant acceleration and depends on cosmological constant Λ, which represents the vacuum energy. In this case, the wheel is stationary, so the expansion will continue indefinitely. But let’s look at another, less well-known model: it assumes the presence of dynamic dark energy, that is, changing over time.
More precisely, dark energy will be like matter defined by a standard field called essence. Each point in space is related to the value of this core V (Φ), which depends on the energy density and Theme which surrounds it. Then it changes over time, thus opposing the theory linking dark energy cosmic constant. Ha wavelength It would be the size of the universe, giving it nearly zero kinetic energy. Because the pressure associated with the core depends on the ratio between kinetic energy and potential energythis is negative, and therefore coherent with repulsive energy.
The acceleration will become a deceleration in a few million years
According to this model, the substance can react with ordinary matter when it is in large quantities, such as a star systemor a larger galaxy. Thus, in the beginning of the universe, when it was still compressed, the substance and matter were interacting vigorously, creating a kind of acceleration boom. then on behalf of stars Moving away, the density of the substance decreases to become semi-constant, thus interacting with the substance as well.
In a study published in the journal Proceedings of the National Academy of Sciences, a group of cosmologists explored the idea of substance. Their model predicts many changes to the expansion of the universe: first, its acceleration will slow and soon stop, and then instead of expanding the universe will shrink little by little. Their calculations postulate a gradual increase in kinetic energy and a parallel decrease in potential energy: hence the evolution towards positive pressure that tends to contract rather than expand the universe: As the positive potential energy density decreases and the kinetic energy density exceeds that, the current phase of accelerated expansion will end and smoothly transition into a period of decelerated expansion. Then, as the scalar field continues to reduce the potential, the potential energy density will become negative enough for the total energy density, hence a parameter Hubble H
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