A team of astronomers has used NASA's Hubble Space Telescope to reveal that the universe is expanding approximately five to nine percent faster than expected.
The data - set to be published in The Astrophysical Journal - was obtained by refining the universe's expansion rate to a level of accuracy unprecedented in the field. Using innovative techniques to improve the precision of distance measurements, the team was able to reduce uncertainty to just 2.4 percent.
"This surprising finding may be an important clue to understanding those mysterious parts of the universe that make up 95 percent of everything and don't emit light, such as dark energy, dark matter, and dark radiation," said Adam Riess of Johns Hopkins University and lead author of the study.
The team looked for galaxies possessing both Cepheid stars and Type Ia supernovae, which can be used for distance determination due to their brightness. After measuring the brightness of 2,400 Cepheid stars in 19 galaxies, the team calculated their distances to approximately 300 Type Ia supernovae in other distant galaxies.
Using these distances, the team compared them to the expansion of space by using the stretching of light from receding galaxies. Afterwards, the two values were used in the calculation of the universe's expansion with time, also called the Hubble constant.
The results revealed a new Hubble constant with a value of 73.2 kilometers per second per megaparsec, which means that in another 9.8 billion years, the distance between cosmic objects with double.
Since this constant doesn't match the predicted expansion rate of the universe, the team used data from the big bang by NASA's Wilkinson Microwave Anisotropy Probe (WMAP) and the European Space Agency's Planck satellite mission to determine that the predictions are approximately five to nine percent smaller than the Hubble constant in the current study, suggesting that the universe is expanding faster than we thought.
"If we know the initial amounts of stuff in the universe, such as dark energy and dark matter, and we have the physics correct, then you can go from a measurement at the time shortly after the big bang and use that understanding to predict how fast the universe should be expanding today," Riess said. "However, if this discrepancy holds up, it appears we may not have the right understanding, and it changes how big the Hubble constant should be today."
The findings were published in the May 17 issue of the pre-print server arXiv.
