The universe’s expansion rate has fascinated astronomers for a long time. Since the initial studies by Edwin P. Hubble and Georges Lemaitre in the 1920s to the discovery of ‘dark energy’ in the 1990s, the field has advanced slowly but steadily. The Hubble Space Telescope has provided a huge amount of data to study and is one of the most potent space-based observatories, helping astronomers understand cosmic mysteries.
In 30 years of existence, the telescope has taken over 1.3 billion photographs. It is now focusing on a more challenging mission — finding how quickly the universe is expanding. So far, the findings suggest that something unusual is happening in the universe, NASA said.
Technological advancements means that scientists can now study the universe’s expansion much more precisely. And there seems to be a discrepancy. NASA said there was a difference in the rate of the universe’s expansion and observations after the Big Bang, suggesting “something weird” was going on.
“The cause of this discrepancy remains a mystery. But Hubble data, encompassing a variety of cosmic objects that serve as distance markers, support the idea that something weird is going on, possibly involving brand new physics,” NASA said.
To understand the phenomenon, they are studying data gathered by the Hubble Space Telescope on a set of “milepost markets” in space and time that can be used to track the expansion rate as they move away.
NASA said the telescope had calibrated more than 40 “milepost markers” since its launch in 1990.
“You are getting the most precise measure of the expansion rate for the universe from the gold standard of telescopes and cosmic mile markers,” Nobel laureate Adam Riess of the the Johns Hopkins University in Baltimore, Maryland, and Space Telescope Science Institute said.
The study of the universe’s expansion began in 1920 with measurements by Hubble and Lemaitre. Hubble said galaxies outside the Milky Way appeared to be moving away from it. He added that the further they were from the Earth’s galaxy, the faster they were moving away. Since then, scientists have been trying to measure this expansion.
When the telescope started gathering data, it discovered that the rate of expansion was quicker than models had predicted — 67.5 km per second per megaparsec against observations of around 73.
This discrepancy made scientists reassess their understanding and start over. The scientists are now waiting for the new James Webb Space Telescope to start sending data so that they can dive deeper into this mystery.