The Rate of Expansion of the Universe Further Refined By Scientists

The Hubble Constant, the unit used to measure the rate at which the universe is expanding, just got a bit of an overhaul thanks to a team of scientists spanning the globe. 

The scientists led by Marco Ajello, Abhishek Desai, Lea Marcotulli and Dieter Hartmann of Clemson University collaborated with six other scientists to create the new measurement using state-of-the-art technologies and techniques.

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Clemson scientists get more precise with the speed of expansion 

“Cosmology is about understanding the evolution of our universe – how it evolved in the past, what it is doing now and what will happen in the future,” said Ajello, an associate professor in the College of Science’s department of physics and astronomy in a press release highlighting the results. “Our knowledge rests on a number of parameters – including the Hubble Constant – that we strive to measure as precisely as possible. In this paper, our team analyzed data obtained from both orbiting and ground-based telescopes to come up with one of the newest measurements yet of how quickly the universe is expanding.”

Edwin Hubble, the American astronomer who lived from 1189-1953, came up with the concept of the expanding universe.  He was the first astronomer to conclude there were multiple galaxies and that they were moving away from each other at a speed that was in proportion to their distance. Hubble had estimated the expansion at a rate of 500 kilometers per second per megaparsec. Megaparsec is around 3.26 million light-years.

With the use of skyrocketing tech, astronomers refined that measurement to a rate of between 50 and 100 kilometers per second per megaparsec. Those measurements have gotten even more precise over the years. 

New insights come from more precise calculations

Now the Clemson scientists, using the latest gamma-ray attenuation data from the Fermi Gamma-ray Space Telescope and Imaging Atmospheric Cherenkov Telescopes concluded the rate is 67.5 kilometers per second per megaparsec. 

“The astronomical community is investing a very large amount of money and resources in doing precision cosmology with all the different parameters, including the Hubble Constant,” said Dieter Hartmann, a professor in physics and astronomy. “Our understanding of these fundamental constants has defined the universe as we now know it. When our understanding of laws becomes more precise, our definition of the universe also becomes more precise, which leads to new insights and discoveries.” Their findings were published in The Astrophysical Journal. 

The Clemson scientists have used the same techniques in past work. In an earlier project, the team measured all the starlight ever emitted in the entire history of the universe.