The Atacama Cosmology Telescope in a Chilean desert, recently decommissioned and to be replaced with a stronger telescope, has measured the oldest light in the universe. Deborah Kellner

Unravelling the mysteries of dark matter

  • June 15, 2023

For the first time ever, what we see now through a glass darkly includes dark matter. St. Paul predicted we will one day see this reality, indeed reality itself, face to face (1 Cor 13:12). For now, Jesuit cosmologist Fr. Adam Hincks is pouring over the new dark matter data and working with hundreds of other scientists to expand our understanding of the universe.

Hincks is one of 160 collaborators who early this spring revealed the world’s first ever map of dark matter, covering one quarter of the entire sky. The University of Toronto professor of astronomy and astrophysics, who also holds the Sutton Family Chair in Science within the St. Michael’s College Christianity and Culture program, has been working on mapping the 14-billion-year history of the universe since he was a graduate student at Princeton University in the mid-2000s. Hincks spent those years travelling down to the Atacama desert in Chile, helping to commission the giant Atacama Cosmology Telescope, writing computer programs and refining the instruments that could reach out across hundreds of millions of light years to show us what happened at the dawn of time.

Hincks’ research strives to show us “the baby universe.” The key to it all is the very oldest light there is — the “cosmic microwave background.”

The dark matter that Hincks and his colleagues have mapped is not a trivial part of reality. It is 85 per cent of all the matter there is. And we hardly know anything about it.

“Two or three decades ago, astronomers were studying how stars were moving in galaxies and how galaxies were moving relative to each other. They couldn’t explain, they couldn’t figure out, what was causing all of that motion,” Hincks told The Catholic Register. “There wasn’t enough mass to cause the stars and the galaxies to orbit in the ways that they were. So they deduced that there had to be more matter there than we could see.”

The matter we can see glows. Dark matter is not like that.

“We don’t know, physically, what it’s made out of,” said Hincks. “We know that regular matter is made out of atoms that have a nucleus, a proton and neutrons and then electrons going around. We understand how ordinary matter works. This dark matter, we don’t know what it’s made of. We just know that it’s there.”

Hincks and his collaborators have figured out that dark matter is cold. They also know that, just like the matter we can see, dark matter is pretty much everywhere. The map, produced by the Atacama Cosmology Telescope using a technique called “gravitational lensing,” shows that it’s not evenly distributed. Dark matter is organized into a kind of web, with filaments of the cold, unseen stuff reaching out across the universe to connect with massive clumps or knots, leaving some parts of the universe a lot emptier than others.

“As we make more and more measurements of its properties, surely we can learn more and more about what it might be made of,” Hincks said.

Not knowing is the very thing that makes science exciting for Hincks. In just the way that young children constantly ask“why?”scientists delight in finding new questions waiting to be asked.

“Scientists, at our best, are like that small child,” he said.

The man who came up with the very theories that drive the entire field of modern cosmology had the same insight in the middle of the last century.

“The important thing is not to stop questioning. Curiosity has its own reason for existence. One cannot help but be in awe when he contemplates the mysteries of eternity, of life, of the marvellous structure of reality. It is enough if one tries merely to comprehend a little of this mystery each day,” Albert Einstein told Life Magazine in 1955. 

Hincks explains the centrality of not knowing, and the questions that arise from what we don’t know, with the help of another Canadian Jesuit — philosopher, theologian and economist Fr. Bernard Lonergan.

“Lonergan said somewhere that as human beings we want to know everything about everything. But the paradox is that we definitely don’t know everything,” Hincks said. “So we have this thirst, or this desire, to know more. The more we know, the more questions we have… That’s kind of deeply significant both about who we are as human beings, but then also about reality itself — that this universe we live in can’t be, at least not yet, contained or grasped by the human intellect.”

Far from excluding the intellect from the life of faith, not knowing but seeking to know is how a human being engages faith.

“There’s an analogy to the journey of faith,” Hincks said. “On the journey of faith, we’re seeking to grow more and more in our relationship with God, to grow in holiness, to grow in knowledge of Him, to grow in charity and love for our brothers and sisters. In that journey there’s always more to learn.”

The knowledge Hincks gathers, along with the data he collects and the questions he asks, does not render the insights of the past disposable. Centuries old theological insights still move Hincks.

“St. Thomas Aquinas spoke about God being in all things most intimately,” he said. “He says that near the beginning of the Summa Theologica.”

The Jesuit immediately links that insight to the spirituality of St. Ignatius of Loyola.

“St. Ignatius will also talk about God labouring in creation — labouring in creation to achieve His purposes and to bring about salvation, and to attract and to draw human beings to Himself.”

As science expands our understanding of the natural world by revealing to us more and more about dark matter, Hincks feels an increasing need to be connected with the natural world of our ordinary existence.

“There’s a real value to not forgetting creation down here on Earth,” he said.

The desert telescope Hincks helped commission in 2007 was decommissioned in September last year and the new Simons Observatory is being built right next door to the ACT in Chile. Its greater capabilities are encouraging Hincks to ask even more questions. He wants to know more about some of the most distant galaxies in the universe.

“These galaxies have giant black holes in the middle of them that create these enormous jets of matter that just flow out and glow very brightly,” he said. “We’re studying those galaxies.”

And the reality we face just gets bigger and bigger.

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