Australasian Science: Australia's authority on science since 1938

Exclusive articles for subscribers

By Stephen Luntz

Subscribe now for access to exclusive online articles

The full text of this article can be purchased from Informit.

Distant Galaxies Rarer
Gravitational lensing is creating the impression that there were more galaxies in the early universe than actually existed, a paper in Nature has concluded.

Gravitational fields cause light to bend, and galaxies are powerful enough to bend light around them to form a lens, making distant objects brighter than they would otherwise be.

“There are only a few direct lines-of-sight to very distant objects in space,” says Prof Stuart Wyithe of the University of Melbourne’s School of Physics. “Our finding shows images from the earliest galaxies reach us more often via a gravitationally bent path. What you see is not exactly what is really there.”

The lens effect often distorts the shape of the galaxy, but more importantly means that cosmic censuses overestimate the number of galaxies appearing in the first 500 million years of the universe’s existence.

Wyithe says the finding does not overthrow models of the development of the universe: “The information we have about star formation this early in the universe is very meagre”. However, he thinks it is something that will need to be taken into account when the James Webb Space Telescope begins a much more detailed survey of the most distant galaxies.

Exercise Can Feed Unhealthy Cravings
An insight has been gained into why some...

The full text of this article can be purchased from Informit.