In 1998, researchers discovered, through two parallel studies, thatmoved faster and faster away from each other. Those questions of considered as a landmark in also called because their 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 that was about to expand, but the model of it 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 onenegative caused by an unknown substance. Named ” “, 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 which presupposes constant acceleration and depends on , 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. Each point in space is associated with a value of this quintessence V (Φ), which depends on the energy density and which surrounds it. It then varies over time, and is thus against the theory that associates dark energy with . Her 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 this 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, 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 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, 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 H