Dark matter is estimated to be make up 27% of the Universe and has been described as the glue that holds everything in place. A new study suggests that amount of dark matter might be declining, as a result of being consumed by dark energy. If correct, there are some serious implications for the future of the Universe. Valentina Salvatelli of Università di Roma was lead author of the paper, published in the journal Physical Review Letters.
Dark energy and dark matter do not emit, reflect, or absorb light, which means they cannot be detected directly with any existing technology. This makes it difficult to study and test their nature. Astronomers study these concepts indirectly based on the structure of the Universe and perceived gravitational influence on matter and radiation that can be detected and measured.
"This study is about the fundamental properties of space-time. On a cosmic scale, this is about our Universe and its fate. If the dark energy is growing and dark matter is evaporating we will end up with a big, empty, boring Universe with almost nothing in it,” stated senior author David Wands in a press release. "Dark matter provides a framework for structures to grow in the Universe. The galaxies we see are built on that scaffolding and what we are seeing here, in these findings, suggests that dark matter is evaporating, slowing that growth of structure.”
Nearly 20 years ago, a discovery that resulted in the 2011 Nobel Prize in Physics revealed that the expansion of the Universe isn’t constant or slowing—it is accelerating. It was believed that the density of dark energy served as the "cosmological constant” and the vacuum of space provided the expansive force.
Using data from sources including the Sloan Digital Sky Survey, Wands’ team compared growth patterns. He believes his team has found what appears to be evidence of dark energy draining dark matter in a way that cannot be explained by existing models. Wands notes that the amount of available data currently available far exceeds that which existed when that theory was made before the turn of the millennium, and the standard model simply does not encompass everything. They propose that dark energy is increasing through an exchange with dark matter.
"Since the late 1990s astronomers have been convinced that something is causing the expansion of our Universe to accelerate. The simplest explanation was that empty space - the vacuum - had an energy density that was a cosmological constant,” Wands continued. “However there is growing evidence that this simple model cannot explain the full range of astronomical data researchers now have access to; in particular the growth of cosmic structure, galaxies and clusters of galaxies, seems to be slower than expected.”
Not everyone is completely sold that this new hypothesis explains everything. Dragan Huterer of the University of Michigan, who was not involved with the research, noted that the modeling used in the paper was a simple one which did not include any interactions, and simplified scenarios such as this have already been known to have trouble fitting precisely in line with current theories. However, due to the mysterious nature of dark energy and dark matter, this new hypothesis should be considered going forward with this type of research.