Analysis of data from the 10 m South Pole Telescope is providing new support for the most widely accepted explanation of dark energy – the source of the mysterious force that is responsible for the accelerating expansion of the Universe.
The results also are beginning to home in on the masses of neutrinos, the most abundant particles in the universe, which until recently were thought to be without mass. The data strongly support the leading model for dark energy, Albert Einstein’s cosmological constant – a slight modification to his theory of general relativity – even though the analysis was based on only a fraction of the SPT data collected and only 100 of the more than 500 galaxy clusters detected so far.
“With the full SPT data set, we will be able to place extremely tight constraints on dark energy and possibly determine the mass of the neutrinos,” said Bradford Benson, a postdoctoral scientist at the University of Chicago’s Kavli Institute for Cosmological Physics. Benson presented the SPT collaboration’s latest findings on April 1 at the American Physical Society meeting in Atlanta, USA.
The most widely accepted property of dark energy is that it leads to a pervasive force acting everywhere and at all times in the Universe. This force could be the manifestation of Einstein’s cosmological constant, which effectively assigns energy to empty space, even when it is free of matter and radiation. Einstein introduced the cosmological constant into his theory of general relativity to accommodate a stationary universe, the dominant idea of his day. He later considered it to be his greatest blunder after the discovery of an expanding Universe.
In the late 1990s, astronomers discovered that the expansion of the Universe appeared to be accelerating, according to cosmic distance measurements based on the brightness of exploding stars. Gravity should have been slowing the expansion, but instead it was speeding up. Einstein’s cosmological constant is one explanation of the observed acceleration of the expanding Universe, now supported by countless astronomical observations. Others hypothesise that gravity could operate differently on the largest scales of the Universe. In either case, the astronomical measurements are pointing to new physics that have yet to be understood.
Source: University of Chicago