It was only 20 years ago, when astronomers discovered that the universe was expanding at an accelerated rate. Without an obvious cause, the concept of dark energy was introduced. Dark energy exerts a force on the universe and is thought to make up 68 percent of it.
However, there are no accepted candidates for what dark energy is and the debate about its very existence has raged since its first proposal. A new paper, published in the Monthly Notices of the Royal Astronomical Society, suggests that we might not need dark energy after all.
The study, led by researchers at the Eötvös Loránd University in Hungary, suggests that matching precise astronomical observations with the approximated models of the universe might have created the need for dark energy while, in reality, it doesn’t exist. In the words of Shakespeare, the fault is not in our stars but in ourselves.
The different regions in the universe, they believe, expand at different rates depending on how matter is distributed there while the cosmos retains an average accelerated expansion. Current standard models don't take this into consideration.
"Einstein’s equations of general relativity that describe the expansion of the universe are so complex mathematically, that for a hundred years no solutions accounting for the effect of cosmic structures have been found,” co-author Dr László Dobos, said in a statement.
“We know from very precise supernova observations that the universe is accelerating, but at the same time we rely on coarse approximations to Einstein’s equations which may introduce serious side-effects, such as the need for dark energy, in the models designed to fit the observational data."
To test this the researchers constructed a computer simulation to compare a standard cosmological model (with normal matter, dark energy, and the equally mysterious dark matter) with one that only had dark matter and normal matter. The requirement was that the latter one, known as the Avera (Average Expansion Rate Approximation) model, has the same critical density as the standard model.
The simulations show a good agreement between each other and between the observations both in the early and recent universe. The Avera model does actually better match the apparent discrepancy between the local and past expansion rates of the universe.
This idea is an intriguing addition to the universe expansion debate, although it is still too early to tell if it can deal a fatal blow to dark energy.