New data from NASA‘s Hubble Space Telescope has highlighted that there are discrepancies in the two techniques for measuring the universe’s expansion rate.
The findings from the Hubble Space Telescope suggest that new theories of physics could be needed to explain the forces behind the universe’s expansion.
The lead researcher and Nobel laureate Adam Riess of the Space Telescope Science Institute (STScI) and Johns Hopkins University, in Baltimore, Maryland, explained: “This is not just two experiments disagreeing. We are measuring something fundamentally different. One is a measurement of how fast the universe is expanding today, as we see it. The other is a prediction based on the physics of the early universe and on measurements of how fast it ought to be expanding. If these values don’t agree, there becomes a very strong likelihood that we’re missing something in the cosmological model that connects the two eras.”
Cosmic distance ladder
Scientists use a “cosmic distance ladder” to determine the distance of objects in the universe. The method depends on accurate measurements of the distances to nearby galaxies, with stars as mileposts.
Astronomers use these values along with other measurements of the galaxies’ light to calculate the universe’s rate of expansion (relating distances to the redshifts of galaxies, the amount of light which is stretched as it travels to Earth through the universe), known as the Hubble constant.
The previous Hubble constant estimates have ranged from between around 67 to 73 kilometres per second per megasec. This means that they estimated that two points in space 1 megaparsec apart, the equivalent of 3.26 million lightyears away, are moving away from each other at the speed of between 67 to 73 kilometres.
Riess added: “The Hubble tension between the early and late universe may be the most exciting development in cosmology in decades. This mismatch has been growing and has now reached a point that is really impossible to dismiss as a fluke. This disparity could not plausibly occur just by chance.”