Researcher computes universe’s expansion speed

A researcher has come up with one of the most accurate measurements ever made of how fast the universe is expanding.

Florian Beutler, doctoral candidate with the International Centre for Radio Astronomy Research (ICRAR) at The University of Western Australia, has calculated how fast the universe is growing by measuring the Hubble constant.

"The Hubble constant is a key number in astronomy because it's used to calculate the size and age of the universe," said Beutler.

The Hubble constant links how fast galaxies are moving with how far they are from us, the Monthly Notices of the Royal Astronomical Society reports.

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, according to an ICRAR statement.

Beutler tackled the problem using a completely different method. He draws on data from a survey of more than 125,000 galaxies carried out with the UK Schmidt Telescope in eastern Australia.

Called the 6dF Galaxy Survey, this is the biggest survey till date of relatively nearby galaxies, covering almost half the sky.

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, Beutler has measured the Hubble constant with an uncertainty of less than five percent.

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