The long-held theory that the rapid expansion of the universe is led by a mysterious force called dark energy has been challenged by a new study.
The study by a team of Hungarian and American scientists noted that the current standard models of the universe are flawed as these fail to consider the impact of the large-scale structure of the universe. An illusory concept like dark energy would not have crept in if the changing structure of the universe has been rightly considered.
Dark Energy Concept Questioned
Led by Gábor Rácz of Eötvös Loránd University in Hungary, the study questioned dark energy by offering an alternative to the reigning cosmological models.
The study spots flaws in the current models in terms of approximations for the origin and evolution of the universe and staggering neglect of its structure and matter.
"Our findings rely on a mathematical conjecture which permits the differential expansion of space, consistent with general relativity, and they show how the formation of complex structures of matter affects the expansion," said László Dobos, co-author of the paper and also from the same university.
According to Dobos, many vital issues were sidelined in the earlier models. If these are taken into perspective, it is easy to explain the acceleration of the cosmos without dark energy as a factor.
Dobos noted that the theory of relativity still remains the key to understanding of the universe's evolution. But Dobos highlighted "coarse approximations" to Albert Einstein's equations of relativity as having side effects - the need to point to dark energy - in order to back up observational data.
Dark Energy As A Pervasive And Mysterious Force
Ever since the Big Bang happened 13.8 billion years ago, triggering the birth of the universe, the cosmos has been expanding. That the universe is expanding was asserted by astronomer Edwin Hubble and has been proven by studies of galaxies.
Enthusiasts of dark energy have been projecting it as a mysterious force accelerating the growth of universe. It is believed that dark energy makes up 68 percent of the observable universe's energy.
In the latter part of 20th century, "dark matter" came into prominence, with astronomers asserting its evidence to explain the movement of stars within galaxies. They said dark matter is covering 27 percent of the universe's total content, with "ordinary matter" confined to just 5 percent.
In the case of dark energy, the concept unfurled as a new component in the 1990s from the studies on explosions of white dwarf stars in supernovae.
Dark energy currently has no properties describing the nature of its existence, which is why it's assumed to be an essential part of empty space referred to as the cosmological constant, represented by the Greek letter lambda (Λ). The cosmological constant was proposed by Einstein for explaining why the scattered mass through the universe is not pulling back under its own gravity.
The combination of dark matter and dark energy as factors in explaining the evolution of the universe is what is known as the Lambda Cold Dark Matter (ΛCDM) model, and it assumes that the universe expands uniformly. While this model is based mostly on Einstein's general theory of relativity, it still leaves much to conjecture.
These approximations are what the researchers of the new study are contesting, saying that these assumptions fail to take into account how large-scale structures in the universe influence its expansion.
New Expansion Model
The new mathematical simulations on the expansion of the universe take into consideration how gravity influences the particles that represent dark matter. The new model shows how matter clumps together and how matter is not distributed evenly in space. The large-scale structures, which look like empty spaces, create sections where evolution happens at different rates.
The new model counters the Lambda Cold Dark Matter model and says the expansion varies at different regions depending on the structural changes.
If the new finding receives acceptance, it will impact many models about the evolution of the universe and research in physics.
The study has been published in the Monthly Notices of the Royal Astronomical Society.
Euclid Mission Of ESA To Study Dark Matter
Meanwhile, the Euclid mission of the European Space Agency will be studying dark energy and dark matter.
Expected to be launched in 2020 aboard a Soyuz rocket from French Guiana, Euclid will take an average 30 days to make its way to gravitationally stable area Lagrange point. It will have a course of six years and 15,000 square degrees of sky in its survey.