How Fast Is The Universe Expanding?

Astronomers have recently discovered that the universe is expanding faster than what other scientists had previously thought.

Space.com reported that scientists have estimated the Hubble constant at about 44.7 miles per second per megaparsec (1 megaparsec is equal to almost 326 million lightyears). The universe's expansion rate, which was named after American astronomer Edwin Hubble, was derived after the team observed the behavior of light coming from bright distant galactic cores called "quasars."

The research team led by Sherry Suyu from the Max Planck Institute for Astrophysics in Germany and Frédéric Courbin of the école Polytechnique Fédérale de Lausanne in Switzerland studied how five nearby galaxies affect the light streaming through these quasars. With the use of NASA's Hubble Space Telescope, Spitzer Space Telescope and other ground-based instruments, they based their projections on the spacecraft's measurements of the cosmic microwave background -- the light scientists believe was left by the Big Bang 13.82 billion years ago.

This unique method landed them to a higher rate compared to what the European Space Agency announced in 2015. According to the ESA's satellite mission, the Hubble constant was about 41.6 miles per second per megaparsec.

"Our method is the most simple and direct way to measure the Hubble constant, as it only uses geometry and general relativity - no other assumptions," Courbin said in a statement.

According to the press release, the Planck estimation, however, agrees with another set of calculations based on Cepheid variable stars and supernovae. This was announced by the team led by Nobel laureate Adam Reiss in 2016.

"The expansion rate of the universe is now starting to be measured in different ways with such high precision that actual discrepancies may possibly point towards new physics beyond our current knowledge of the universe," Suyu explained.

This study will be published in a series of five papers in the journal Monthly Notices of the Royal Astronomical Society.