It’s not news that the universe is expanding, but a team of astronomers have discovered that the universe is expanding at a 5 to 9 percent faster rate than scientists initially believed. This discovery is a result of the efforts of John Hopkins University and the Space Telescope Science Institute, led by Nobel Laureate Adam Riess.
“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,” Riess said.
Riess and his team used stars and supernovae as “cosmic yardsticks.” They measured the brightness of 2,400 Cepheid stars in 19 different galaxies, which pulsate in a way that allows scientists to compare their true brightness to their apparent brightness and figure out how far away they are, and 300 Type Ia supernovae, which flare with a brightness so reliable it can be used to measure distance.
“You start at two ends, and you expect to meet in the middle if all of your drawings are right and your measurements are right. But now the ends are not quite meeting in the middle and we want to know why,” explained Riess.
Riess and his team estimate the rate of expansion is 45.5 miles per second per megaparsec (3.26 million light-years). That means that the distance between cosmic objects will double in another 9.8 billion years.
The team made the discovery by refining the measurement of how fast the Universe is expanding, a value called the Hubble constant, to unprecedented accuracy, reducing the uncertainty to only 2.4 percent.