The universe is expanding much faster than we thought! Nasa and the European Space Agency concluded together that the “universe is expanding 5% to 9% faster than predicted.” They used the Hubble Space Telescope to discover these findings. Just as a reminder for those that don’t remember, the Hubble Space Telescope was launched into low Earth orbit in 1990. It orbits outside Earth’s atmosphere and takes high-resolution images. These images allow astrophysicists to determine the rate of expansion of the universe.
Nasa and the European Space Agency used the Hubble Space Telescope to “measure the distance to stars in 19 galaxies beyond the Milky Way.” Scientists are trying to understand why the current rate of expansion did not match previous predictions from measurements of radiation left over from the Big Bang. Adam Riess, a U.S. astrophysicist and Professor at Johns Hopkins University and the Space Telescope Science Institute said, “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.”
The researchers discovered the new expansion rate is 73.2 kilometers per second per megaparsec. A megaparsec is 3.26 million light years. The problem is that the “speeds do not match predictions for an expansion rate from other observations made by Nasa’s Wilkinson microwave anisotropy Probe, or the European Space Agency’s Planck satellite.” One showed the cosmic expansion rate at 5% and one at 9%. The probe and the satellite were put into orbit to observe the aftermath of the Big Bang when space and matter were created.
One reason for the difference in rates may be that there are unknown subatomic particles that travel as fast as the speed of light. Another possibility for the discrepancy could be due to another idea called “dark energy.” Dark energy is a mysterious anti-gravity force that could be pushing galaxies away from each other causing the rate of expansion to increase.
Reiss stated, “This may be an important clue to understanding those parts of the universe that make up 95% of everything and that don’t emit light, such as dark energy, dark matter and dark radiation.”
Another team member, Lucas Macri of Texas A&M University added, “We know so little about the dark parts of the universe, it’s important to measure how they push and pull on space over cosmic history.”
As the Hubble space telescope continues to orbit, distance estimates become more precise calculations. Each bit of information slowly adds on to the big picture of how the Earth is expanding. Reiss and his team’s research will be published in the Astrophysical Journal.