How did the Universe light up – filling a billion years of cosmic history: 2011 Malcolm McIntosh Prize for Physical Scientist of the Year

Prime Minister’s Prizes for Science, Prime Minister’s Prizes for Science 2011

Stuart Wyithe

The Universe was born in a hot Big Bang. But after 300,000 years of expansion it became a cold dark place—no galaxies, no stars, no light. A billion years later nuclear fusion lit up the Universe as hydrogen atoms clumped to form stars and galaxies.

We can still detect the heat of the Big Bang. And our best telescopes can see the light of the early galaxies. But how did the first stars and galaxies form? What triggered the cosmic dawn? What happened during the Universe’s billion-year Dark Age?

This is one of the great unknown eras of cosmic history—particularly because there is no light nor other forms of high energy radiation to analyse. Stuart Wyithe’s theories may lead to some answers.

The ideas that this young theoretical physicist is generating on pen, paper and desktop computer will guide the questions to be asked by a new multi-billion-dollar generation of telescopes including the Square Kilometre Array, the James Webb Space Telescope, and the Giant Magellan Telescope.

For his work on the physics of the formation of the Universe, Professor Stuart Wyithe receives this year’s Malcolm McIntosh Prize for Physical Scientist of the Year.

“Stuart Wyithe is the best young scientist with whom I have ever worked in almost 35 years on the faculties of Harvard and Princeton, bar none,” says Professor Edwin Turner of the Princeton University Observatory, “and he is by far the most productive and prolific. He is also the most important and influential theoretical astrophysicist in Australia and among the top 10 or so in the world in my judgment.”

Stuart Wyithe became interested in astronomy when he was young. He grew up in the Blue Mountains where, away from the bright lights of Sydney, the night sky had meaning. At secondary school, he was involved in an astronomy club run by a keen teacher. They used to go camping on the western plains to observe the heavens. (Closer to home, he also became an inveterate rock climber.)

He describes his introduction to academic life as ‘chequered’—moving to Sydney, enrolling in chemical engineering, and then quitting after two years to go travelling. When he returned, it was to finish an honours degree in physics at the University of Melbourne. By this time, he knew what he wanted to do and immediately enrolled in a PhD in astrophysics.

After his first year, Stuart took advantage of a Visiting Student Research Collaborator program to go to Princeton, initially for a semester. That was the last Australia saw of him for several years. He completed his doctorate at Princeton, and then he moved on to Harvard University as a NASA Hubble Fellow, not entirely without ulterior motive. “There was a woman involved, of course,” Stuart says. “She is now my wife.” She’s also a leading young researcher at the Walter and Eliza Hall Institute of Medical Research.

Stuart Wyithe (credit: Prime Minister’s Science Prizes/Bearcage)

The time in America was very productive. “[Stuart and I] are co-authors of 15 papers in the refereed literature,” says Edwin Turner, “of which 11 were submitted during his graduate school years. He is deservedly first author of all but one of these publications, and carried out the work for the majority of them during his two years in Princeton. It is clear that he is an exceptionally energetic and efficient worker. The quality of his work is no less impressive.”

In fact, in the 14 years since he started his PhD, Stuart has published more than 100 papers, five of which appeared in the prestigious British journal Nature, and for the vast majority of which he has been the lead author.

He was also once one of Australia’s top rock climbers, although, with a young family, he has curtailed this activity somewhat. At one stage some years ago, he held the dual distinction of having made the climb rated most difficult by any Australian and also the most difficult climb ever made by anyone within Australia.

Initially Wyithe worked on gravitational microlensing, a technique used to gain information on distant stars and on planets outside the solar system by observing the bending of light as it passes through a gravitational field. Nearby stars, for instance, bend the light of more distant stars as it passes in front of them.

But more recently Stuart’s work has focused on the evolution of the structure of the Universe. “Astronomy is all about trying to understand how the Universe came to look the way it does, as well as how it works. What’s not understood is how the galaxies themselves formed. This is inexorably linked with the transition from a Universe of cold, uncharged, atomic hydrogen to being ionised and hot. This ‘Epoch of Reionisation’ is the last non-understood event in the history of the Universe.”

Stuart Wyithe (credit: Prime Minister’s Science Prizes/Bearcage)

“The obvious candidate for the energy that drove this process is the formation of stars, and that is where most attention has been focused.” Another possible source is the formation of supermassive black holes. And it is in these two possibilities that Stuart has been most interested.

“The reason that Wyithe’s work has had so much impact,” says Professor Matthew Colless, Director of the Australian Astronomical Observatory, “is that not only does it elucidate a fundamentally important epoch in cosmic evolution, but it has also focused on making explicit, detailed and testable predictions for the large-scale structures that should be observed. These predictions strongly suggest that there are rich observational signatures of the Epoch of Reionisation just beyond the limit of current facilities.”

The next generation of powerful astronomical instruments either planned or under construction—the Square Kilometre Array, the James Webb Space Telescope, the Giant Magellan Telescope, and Australia’s own Murchison Widefield Array and Skymapper—is designed to plug this information gap.

“The study of the cosmic dawn is deemed to be of such importance that the top recommendation of the 2000 decadal survey in astronomy and astrophysics in the US, which I co-chaired, was [to build] a successor to the Hubble Space Telescope to address this problem,” says Professor Christopher McKee of the University of California, Berkeley.

“Furthermore, that committee also recommended that the US participate in initial work on a very large radio telescope, the Square Kilometre Array (SKA), which would be able to observe the universe in this epoch.”

Stuart Wyithe (credit: Prime Minister’s Science Prizes/Bearcage)

Australia and South Africa are competing to host the SKA, a giant radio telescope that will cost some two billion dollars to construct.

Stuart Wyithe now chairs the science committee for the Murchison Widefield Array, a revolutionary electronic telescope being constructed by a US-Australian-Indian consortium in Western Australia. It will test some of the ideas to be incorporated into the SKA.

“In my view,” says Professor McKee, “by illuminating our origins, Dr Wyithe’s work benefits all mankind. On a far more practical level, if his contributions to the proposal to build the SKA in Australia are successful, he will certainly have benefited his nation.”


2003 PhD (Astrophysics), The University of Melbourne
1997 Bachelor of Science (Honours), The University of Melbourne

Career highlights

2011–2017 Melbourne node leader, Australian Research Council (ARC) Centre of Excellence for All-sky Astrophysics
2011–2016 ARC Australian Laureate Fellow
2011–2013 Editorial Board for Scientific Reports, Nature Publishing Group
2010–2011 Chair, Murchison Widefield Array Science Council
2009 Pawsey Medal, Australian Academy of Science
2008–2010 ARC Discovery Project: Imaging the dark ages of the Universe and understanding the early evolution of the Universe. S Wyithe, RJ Sault, J Hewitt
2008–2009 ARC Linkage International Project: The first galaxies and the end of the dark ages of the Universe. S Wyithe, A Loeb, M Dijkstra
2008 David Syme Research Prize, Faculty of Science, The University of Melbourne
2007–2011 ARC Discovery Project Queen Elizabeth II Fellow, School of Physics, The University of Melbourne
2007 Edgeworth David Medal, Royal Society of NSW
2006 Woodward Medal for Science and Technology, The University of Melbourne
2006 Dean of Sciences Award for Excellence in Research, Faculty of Science, The University of Melbourne
2006 Named one of the inaugural Cosmos Magazine ‘Bright Sparks’
2006-present Lecturer progressing to Professor (in 2010), School of Physics, The University of Melbourne
2005–2007 ARC Discovery Project: End of the dark ages of the Universe. S Wyithe, DG Barnes, A Loeb
2004–2007 ARC Discovery Project Australian Postdoctoral Fellow, School of Physics, The University of Melbourne
2004 Research Fellow, Princeton University
2002–2003 Research Fellow, The University of Melbourne
2001–2002 NASA Hubble Fellow, Harvard University
1999–2001 Visiting Student Research Collaborator, Princeton University
1999 Postgraduate Overseas Research Experience Award

External links

View a profile of Stuart Wyithe at