Victoria Mine Lab to Take the Lead in Dark Matter Research

Dark matter is said to be the dark ring produced in the above photo after two galaxies collide. (NASA, ESA, M. J. Jee and H. Ford et al. (Johns Hopkins Univ.) )

A laboratory one kilometre below ground in regional Victoria is set to become the southern hemisphere’s epicentre for dark matter research.

Plans for the $10 million Stawell Underground Physics Laboratory will take shape deep in an unused section of gold mine.

“In our universe, the matter that we are made of is a very small amount—less than five per cent—(of) all the material of the universe. So we need to understand what the majority of the universe is made of, that’s why we look for dark matter," lab director Professor Elisabetta Barberio told AAP on April 4.

“Dark matter exists. This is the discovery of what type of particle dark matter could be.”

The laboratory will be deep underground where there is no light from the sun or stars.

Tuesday’s federal budget allocated $5 million over two years to the University of Melbourne to start work on the centre.

“The facility will be the first of its kind in the southern hemisphere and will support Australian astroparticle researchers to become global players in dark matter research,” the budget outlined.

The project is a joint venture with Australian National University, Swinburne University of Technology, and the University of Adelaide.

Researchers at the new base hope to compare their results against those of Gran Sasso Underground Physics Laboratory in Italy.

The Commonwealth cash will go towards the excavation and first stage of the lab, expected by the end of 2019.

If the lab is to be used for other activities such as medical research related to cancer and geological erosion, another $5 million is needed to finish the space, Professor Barberio said.

“We hope this extra $5 million will come from the state government,” she said.

“We are in negotiations with the state government. They are very supportive because it will be a very big boost for regional Victoria.”

The state Labor government has been contacted for comment.

Did ‘Dark Matter’ or a Star Called Nemesis Kill the Dinosaurs

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The dinosaur extinction 66 million years ago was most likely caused by a comet or big asteroid hitting the Earth. But given that asteroids don’t actually hit our planet very often, could this really be the whole story? Many scientists are now asking whether some sort of cosmological event could have boosted the number of comets at the time, making such a collision more likely.

In a recent book, American cosmologist Lisa Randall suggests that a huge disk of “dark matter” – a type of invisible matter that is five times more common than “normal” matter – could have been responsible. When sweeping past our solar system such a disk would cause a tiny perturbation in space, amounting to a flicker in the gravitational force that can knock comets out of the solar system’s Kuiper belt or the Oort cloud just outside and send them towards the Earth.

But how credible is this theory? And are there other cosmological events that could explain the issue?

A Tricky Question

Mounting astrophysical and cosmological evidence suggests that there is a lot more dark matter in our galaxy than normal matter. Although it is invisible, we know it is there because of the gravitational pull it has on objects surrounding it.

The fact that it is dark simply means that it does not emit or absorb light, which makes it difficult to spot. Most cosmologists believe this matter, which is after all part of our galaxies and galaxy clusters, moves slowly, and is “cold” (because fast-moving particles are hot).

Randall suggests that there’s a whole disk of dark matter in our own galaxy. For it to have an effect on us it would need to be roughly aligned with the visible disk of the Milky Way so that the solar system oscillates around it as it travels around the galactic centre. But this is problematic because to be able to explain observations made so far, cosmologists believe dark matter would form large spherical halos around galaxies rather than disks.

To get around this, we need to make dark matter weirder than it already is. Randall suggests that there is more than one type of dark matter in the form of a “contamination”, which she says could comprise 5-10% of the total dark matter. This kind of dark matter is different because it can interact with itself just like normal matter does. While the majority of dark matter can flow through itself without stopping, this special so-called “dissipative” dark matter can halt itself from moving and thereby form a galactic disk, like normal matter does. But, as Randall admits in her research papers, we do not know for sure that such dark matter would form a disk.

Konstantinos Dimopoulos contributed to this article