Mapping the universe in 3D will give us a clear picture of that weird invisible stuff that pervades the universe, dark matter.
Credit: SPDO/TDP/DRAO/Swinburne Astronomy Productions
Unlike the debunked 'face' on Mars, the Square Kilometre Array will seek real aliens, expanding the volume of space that can be searched for alien radio signals by a factor of 1000.
Credit: NASA, MRO, MGS, Stereo Anaglyph: Patrick Vantuyne
He may be a genius, but whether Einstein was right about gravity waves - very long amplitude waves that supposedly distort space-time, will form part of the fundamental physics tested by the Square Kilometre Array.
Credit: Ferdinand Schmutzer
ALIENS: the big question is who else is out there? Like SETI (the search for extraterrestrial intelligence), the Square Kilometre Array will scan the sky for radio wave frequencies comparable to those of TV transmitters. But with a baseline of 3,000 to 5,500 km, it will expand the volume of space that can be searched for alien signals by a factor of 1000.
TESTING EINSTEIN: Einstein explained gravity as a curvature in space-time, and the theory of general relativity has withstood stringent tests. The Square Kilometre Array will take this a step further, using the regular 'tick' of pulses of light from distant, compact stars called pulsars and looking at how this regularity - equivalent to the most precise atomic clocks on Earth - stands up in pulsars near massive black holes, which pack some serious gravitational punch.
PROBING MAGNETISM: the universe is magnetic and the effects of these magnetic fields - varying enormously in strength and scale - on the evolution of the cosmos are poorly understood. What makes and maintains these fields is a mystery. "Magnetic fields play a key role in fundamental physical processes throughout the universe," says astronomer Bryan Gaensler from the University of Sydney, who aims to map the magnetism of the Milky Way and beyond using the Australian SKA Pathfinder telescope (ASKAP).
DARK TIMES: Cosmic background radiation revealed the smooth universe 300,000 years after the universe's birth, yet the first stars and galaxies arrived hundreds of millions of years later. Tracing the signal of ancient hydrogen gas before, during and after the first stars formed, the Square Kilometre Array should reveal detailed properties of the universe's first luminous objects.
DARK ENERGY: It drives galaxies further apart and could tell us if, when, and how the universe will end. Charting another billion or so galaxies in the furthest reaches of space in just one year of operation, the Square Kilometre Array will provide a 3D-map of the cosmic web of space and matter, giving us a much better picture of dark energy.
GALACTIC EVOLUTION: What makes galaxies form and grow, how does dark matter - the 'missing' substance that dominates galaxies - fit into the equation and what is it? Whereas projects such as the Sloan Digital Sky Survey have given us a glimpse at the strangeness of distant galaxies, Square Kilometre Array will look at many more galaxies up to 9.5 billion years back into space to see how galaxies evolved then and now.
GROWING EARTHS: Though theories abound, more than 4.5 billion years after our planet formed we're in the dark regarding evidence of planet formation. What we need is to observe the dusty disks of thousands of different stars. Dust has a large surface area, which transforms intercepted starlight into heat - scanning these thermal emissions in detail to understand how planets form will be one of the main tasks of the Square Kilometre Array.
BUILDING SOLAR SYSTEMS: Of the more than 500 exoplanets discovered to date a surprising number are gas giants like Jupiter close to their star. The Square Kilometre Array will look for telltale gaps in the protoplanetary disks around stars to shed light on whether many more stars have these gas giant planets, where in the solar system the planets sit and whether or not they are in the 'habitable zone' of their star.
NEW GALAXIES: The WALLABY sky survey aims to use ASKAP, which can 'see' 2/3 of the sky, to survey large areas of the sky, discovering a good half a million new galaxies and helping to understand why fewer new stars are being born in this latter period of the universe's history. The Square Kilometre Array will take these searches even further.
AND FINALLY: As will all giant tools of science, it's the unexpected discoveries that will most profoundly change our understanding of the cosmos. The Square Kilometre Array will stretch over an area possibly five times larger than the world's biggest radio telescope, the European Low Frequency Array. It's likely the cosmos - infinitely ungraspable in size and complexity - harbours some strange objects and processes that we have not yet begun to imagine.
Heather Catchpole is the deputy editor of Cosmos.
