One of the most accurate surveys of the structure of the universe has suggested that it is “less lumpy” than thought, in findings that could indicate mysterious forces at work.
Posts written by Dark Energy Survey and South Pole Telescope Mapping the distribution of matter with the goal of understanding the competing forces that have shaped the evolution of the universe and governed its eventual destiny. The incredibly detailed analysis adds to evidence suggesting there may be an important component missing from the so-called Standard Physical Model.
“Looks like there are a few less [clumpiness] Eric Baxter, an astrophysicist at the University of Hawaii and co-author of the study, said:
The results don’t cross the statistical threshold that scientists consider strong enough to claim a discovery, but they do follow similar findings from previous surveys showing a gap between theoretical predictions and what’s actually going on in the universe.
“If the results hold, it’s very exciting,” said Dr. Chihuai Chang, an astrophysicist at the University of Chicago and lead author. “The point of physics is to test and solve models. The best case scenario is to help us understand more about the nature of dark matter and dark energy.”
Since the Big Bang 13 billion years ago, the universe has expanded, but matter has also cooled and coalesced as gravity pulled on denser regions, creating a cosmic web of galaxy clusters and filaments. As scientists work to understand this cosmic tug-of-war, a strange picture emerges in which only about 5% of the universe’s contents are explained by ordinary matter. Roughly 25% is what’s called dark matter, which is invisible mass that contributes to gravity, but is otherwise invisible. The remaining 70% is dark energy – a mysterious phenomenon that is said to explain why the expansion of the universe is being accelerated rather than slowed down by gravity.
The latest work uses data from the Dark Energy Survey, which has been surveying the sky for six years from a mountaintop in Chile, and the Antarctic Telescope, which looks for faint traces of radiation crossing the sky from some of the universe’s first moments. Either way, analyzes using a phenomenon called gravitational lensing, in which light bends slightly as it passes through massive objects, such as galaxies and clumps of dark matter, have allowed scientists to infer the distribution of matter in the universe.
Separately, scientists can infer the structure of the earliest universe from the heat left over from the big bang and use computational models to “fast forward” and see if they match observations.
Analysis showed that the material did not “clump” as expected. According to Professor Carlos Frink, a cosmologist at Durham University who was not involved in the study, there are three possible explanations. First, it could be the result of interference with the data or systematic errors in the telescope. It’s also possible that instead of a major rewriting of cosmological theory, poorly understood astronomical phenomena could explain the results. “For example, supermassive black holes at the center of galaxies can generate huge jets of radiation that could, in principle, push matter around and smooth it out a bit,” he said.
A third, more interesting, option is that the difference is explained by entirely new physics, such as the existence of a new type of neutrino, the strange behavior of dark energy, or an unconventional form of dark matter. “Of the three possibilities, I hope it’s the last, I’m afraid it’s the second, but I suspect it’s the first,” said Frink.
Results Published in Physical Review D.
