Universe Size and Expansion Calculation Method Refined by PhD Candidate

A PhD candidate at The International Centre for Radio Astronomy Research (ICRAR) at University of Western Australia in Perth has made the daunting task of calculating the size of the universe by refining the method of figuring out how quickly it is expanding.

Ever wondered how big is the universe? Here's a glimpse: The nearest spiral galaxy to the Milky Way is the Andromeda, which is 2.5 million light-years from Earth but it is not the closest galaxy. That distinction belongs to the Canis Major Dwarf Galaxy, which is a mere 25,000 light-years from Earth. That puts it quite close to Earth because our own solar system is 30,000 light-years away from the center of Milky Way. And, if you're wondering what is a light-year, it is 5,865,696,000,000 miles.

In other words, the universe is pretty huge, to say the least, and astronomers are still trying to calculate its size. The task is daunting but their job may have just become easier thanks to Florian Beutler, who has refined the Hubble constant, which is "a key number in astronomy because it’s used to calculate the size and age of the Universe."

As the Universe expands, other galaxies go farther away from our galaxy, the Milky Way, and the Hubble constant determines how fast they are moving and how far they are from us.

"By analysing light coming from a distant galaxy, the speed and direction of that galaxy can be easily measured. Determining the galaxy’s distance from Earth is much more difficult. Until now, this has been done by observing the brightness of individual objects within the galaxy and using what we know about the object to calculate how far away the galaxy must be," ICRAR reported.

Though based on well-established assumptions, the method is, however, prone to "systematic errors," prompting Beutler to refine the approach.

Beutler’s work draws on data from a survey called 6dF Galaxy Survey, which covers more than 125,000 galaxies and is the biggest survey to date of relatively nearby galaxies.

"Galaxies are not spread evenly through space, but are clustered. Using a measurement of the clustering of the galaxies surveyed, plus other information derived from observations of the early Universe, Mr. Beutler has measured the Hubble constant with an uncertainly of less than 5%," the report said.

Professor Matthew Colless, Director of the Australian Astronomical Observatory and one of Beutler’s co-authors, said Beutler's method of "determining the Hubble constant is as direct and precise as other methods, and provides an independent verification of them."

"The new measurement agrees well with previous ones, and provides a strong check on previous work," the professor said.

According to ICRAR, the measurement "can be refined even further by using data from larger galaxy surveys."