TruthTheOnlyDefense
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In the beginning, the universe was dark. And then the first star ignited, and lo, there was light.
Scientists around the world are racing to pinpoint that first ignition. And thanks to painstaking calculations - and a calamitous stuff-up - Australia is winning.
The prize at stake is a chance to influence the design of one of humanity's most complex scientific experiments, the Square Kilometre Array. Oh, and maybe a Nobel prize.
The array, due for completion next decade, is a set of antennae, spanning the globe, designed to see back to the beginning of the universe.
"It’s very competitive," says Dr Nichole Barry, the University of Melbourne-based scientist who just grabbed the lead.
Dr. Nichole Barry is researching the first star.Credit: Simon Schluter
The first starlight
In the moments after the Big Bang, the universe was filled with simple atoms of hydrogen gas. This black, gas-filled universe is known as the Dark Age.
Gravity slowly pulled the hydrogen together, eventually into huge clumps. The pressure in the centre of those clumps crushed the hydrogen together, causing it to explode. The first stars were born.
"It’s the last major unexplored epoch in the history of our universe," says Professor Steven Tingay, a member of Dr Barry’s team and deputy director of the International Centre for Radio Astronomy Research.
In this artist's impression of the early universe, neutral hydrogen, in red, is gradually ripped apart by the first stars, shown in white. Credit: Paul Geil and Simon Mutch
"We know quite a lot about what happened in the universe immediately after the Big Bang. We have a pretty good handle on what’s going on around us today. What we don’t understand is how we got from the Big Bang to here."
Dr Barry’s team, and teams from around the world, are competing to find the extremely faint energy emitted by the hydrogen gas just before the moment of first ignition.
How faint are we talking? Imagine the tiniest amount of energy you can, says Dr Barry – the energy of a single atom flipping over.
Then let that energy travel for 12 billion years, through stars and planets, galaxies and black holes, until it reaches Earth. That’s the signal everyone is hunting.
A "radio colour" view of the sky above a tile of the Murchison Widefield Array radio telescope. The Milky Way is visible as a band across the sky and the dots beyond are some of the 300,000 galaxies observed by the telescope. Credit:Curtin/ ICRAR/ JohnGoldsmith
Why look for it?
Radiation from the first stars ripped up the hydrogen, killing the signal's source. By capturing the signal, and then looking for areas where the signal stopped, you could spot the first stars in the universe.
"And we have just gotten the closest that anyone has ever come to measuring it," says Dr Barry.
The race to the dawn of time
Three years ago, it looked like the Americans had the race all sown up. PAPER, a South African telescope operated by an American team, published some amazingly good results – orders of magnitude better anything else.
Using complicated math tricks, PAPER thought they had filtered out all the noise, leaving just the hydrogen signal. But on closer inspection, they discovered they had filtered that out too. They had to retract all their results.
"There are two different paths you can take: the path that’s risky, but gets you low limits fast," says Dr Barry.
"Or you can take the harder, more time-consuming path, but more reliable.
"We don’t use a tonne of these fancy mathematical tricks. We’re just extremely precise in everything we do."
Dr Barry’s team, including scientists from America, Canada, Japan and India, uses data from the Murchison Widefield Array, a collection of small antennas that sprawl across the West Australian desert like an invasion-force of alien metal spiders.
To get their result, they spent hundreds of hours hand-tuning the data to get it as precise as possible, yielding the most accurate picture ever of the universe’s Dark Age.
It won’t be forever, though. PAPER are redoing their work and will come back with a new estimate.
"Eventually, my number will be beaten," Dr Barry says. "Hopefully, I will try to beat it myself."
https://www.theage.com.au/national/...ralia-just-took-the-lead-20190909-p52pi8.html
