The universe may be growing at a slower pace than we thought.
A team of Clemson University astrophysicists developed a new technique for quantifying the all-important Hubble Constant.
And their findings pump the breaks on recent kilometers-per-second-per-megaparsec estimates.
The concept of an expanding universe was promoted by astronomer Edwin Hubble (yes, that Hubble).
In the early 20th century, he became one of the first scientists to deduce that the universe was comprised of multiple galaxies; subsequent research revealed that galaxies were moving away from each other at a speed in proportion to their distance.
(A galaxy two megaparsecs—3.26 million light years—away recedes twice as fast as a galaxy one megaparsec away, for example.)
Hubble initially estimated the expansion rate to be around 500 km/s/Mpc (with a megaparsec being equivalent to about 3.26 million light years).
That number, known as the Hubble Constant, has been radically revised over the years—slowed to between 50 and 100 km/s/Mpc)—as science and technology advance.
Now, in a study published by The Astrophysical Journal, Clemson researchers devised a new, slower measurement: approximately 67.5 km/s/Mpc.
“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,” Marco Ajello, an associate professor in Clemson’s department of physics and astronomy, said in a statement.
They used gamma rays and extragalactic background light (EBL) to analyze their hypotheses.
When our understanding of laws becomes more precise, our definition of the universe also becomes more precise, which leads to new insights and discoveries,” Clemson professor Dieter Hartmann added.
A common analogy of the expansion of the universe is a balloon dotted with spots, each one representing a galaxy. When the balloon is blown up, the spots spread further apart.
“Some theorize that the balloon will expand to a particular point in time and then re-collapse,” according to Abhishek Desai, a graduate research assistant in the Clemson department of physics and astronomy.
“But the most common belief is that the universe will continue to expand until everything is so far apart there will be no more observable light,” he continued. “At this point, the universe will suffer a cold death. But this is nothing for us to worry about. If this happens, it will be trillions of years from now.”
Phew.
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