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Dark matter pioneer nets PM's science prize

Ken Freeman

Professor Ken Freeman: his findings changed our understanding of galaxy formation (Source: Bearcage/Prime Minister's Science Prizes)

PM's science prize A renowned astronomer who introduced the revolutionary concept of dark matter has been awarded one of Australia's top science prizes.


"It's a fantastic recognition. It's a real career highlight," says Freeman.

In the late 1960s, Freeman discovered that stars, gas and dust in spiral galaxies were rotating in a way that suggested they only made up a small fraction of galactic mass.

He proposed there must be a large amount of "invisible matter" that exerted the gravity capable of pulling the material in the galaxy inwards, so it didn't just fly off in a straight line.

Freeman's ideas, published in a paper in 1970, led to a decade of debate. Many, including Freeman himself, wondered if some mistake had been made in gathering data on galaxy rotation.

"You have your uncertainties in those sorts of periods," he says.

But in 1978 new data on the rotation of 10 galaxies closed the case, says Freeman.

Eventually, what is now known as "dark matter" came to be accepted.

Today, astronomers believe that a typical galaxy is made up of 97 per cent dark matter and only three per cent luminous matter.

Such a large amount of dark matter had tremendous consequences for galaxy formation, says Freeman.

"It completely changed the whole paradigm of our understanding of galaxy formation," he says.

Recent research suggests dark matter has a spherical shape extending as much as 10 times the distance of stars in a galaxy.

Freeman also found that all galaxies have the same brightness per unit area - something referred to as "Freeman's Law".

"Galaxies are different sizes but the number of stars per unit area is very similar and that hadn't been spotted before," he says.

Together with Professor Joss Bland-Hawthorn, Freeman also founded the field of galactic archaeology, which uses chemical fingerprints in stars to detect "fossils" of the early Milky Way, and gives clues on how it was constructed.

Beating cancer

At the same ceremony Dr Mark Shackleton from the Peter MacCallum Cancer Centre, was awarded the $50,000 Science Minister's Prize for Life Scientist of the Year.

Research by him and colleagues on melanoma changed the way researchers view and develop treatments for cancer.

"The techniques that we developed have enabled us to crack open the inner world of tumours in this disease and study the malignant potential of individual cells," says Shackleton.

He and colleagues challenged the prevailing view that treatments only needed to target the most aggressive melanoma cells within tumours.

"Pretty much every melanoma cell in a tumour is as bad as every other cell in terms of the cell's potential to cause formation of tumours and spread of the cells," says Shackleton.

"The implication was that any therapies that aren't going to eliminate all cells were doomed to be ineffective."

He says this has triggered a "combination therapy" approach to cancer.

"We need to go after every cell and as many different types of cells as possible," says Shackleton.

Cleaner gas

Professor Eric May from the University of Western Australia was awarded this year's $50,000 Malcolm MacIntosh prize for Physical Science for his work towards making liquid natural gas a cleaner resource.

May and his team study the fundamental properties of how fluids behave, particularly the pressure and temperature at which gas is converted to a liquid.

"We're now working on improving the efficiency of the liquefied natural gas process," he says, explaining that current processes burn 10 to 12 per cent of the gas to make liquefied natural gas.

"Even a one or two per cent decrease in that number would have a significant impact on the amount of energy that's being used, and therefore the amount of carbon emissions that are coming from the plant."

May is also researching the potential of reinjecting carbon dioxide back into the gas field to reduce carbon emissions.

Michael van der Ploeg of Table Cape Primary School in Tasmania and Anita Trenwith of Salisbury High School, north of Adelaide will each receive the $50,000 Prime Minster's Prize for Excellence in Science Teaching.

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