‘One little kid told me I was wrong, and he was right – I was delighted!’

10 Jan 2018

Dr John Regan, Marie Skłodowska-Curie fellow at Dublin City University. Image: DCU

DCU’s esteemed astrophysicist and black-hole expert Dr John Regan tells us about the challenge of understanding a universe we know so little about.

Given the sheer scale of the known universe, there is no shortage of questions for astronomers and astrophysicists. In the case of Dublin City University’s (DCU) Dr John Regan, his biggest question is about how black holes are formed.

While currently a Marie Skłodowska-Curie fellow at DCU, Regan’s astronomy research really took off once he acquired his PhD from the Institute of Astronomy at Cambridge University in the UK.

During his time there, he worked on trying to understand the formation of the first supermassive black holes in our universe, with his thesis mapping out some pathways that could provide solutions to how such objects, 1bn times the mass of our sun, could be created so early in the universe.

After Cambridge, he held postdoctoral positions in Helsinki and at the Institute for Computational Cosmology in Durham University before arriving at his current posting in DCU.

In March of last year, Regan made headlines around the world for leading a project that found substantial evidence to support one particular formation theory for supermassive black holes.

The theory suggests that these giants rapidly accumulated mass during the early formation of the universe, as molecular hydrogen cooled and deflated a primordial plasma of hydrogen and helium to form stars and galaxies.

What inspired you to become a researcher?

I remember being asked a question by my physics teacher in secondary school: “What would happen if you travelled away from a clock at light speed?” That concept was mind-blowing for a 14-year-old!

The universe is filled with incredible physics such as neutron stars, objects so dense that a teaspoon amount would weigh 1bn tonnes here on Earth.

By studying the universe, you get to explore the most exotic phenomena we know about and be part of the discovery of new and exciting processes and objects, such as the recent discovery of gravitational waves.

Albert Einstein’s theory of general relativity predicted their existence 100 years ago. We spent at least 20 years building a machine to detect them, and no one knew if it would really work until two years ago.

Now, we have a new window on the universe and we are detecting black holes we wouldn’t otherwise be able to ‘see’, and who knows what else gravitational waves will tell us?

Can you tell us about the research you’re currently working on?

I’m working with colleagues in the US about an idea on how all the supermassive black holes in massive galaxies may have originated from supermassive stars.

These supermassive stars could only form in the early universe, and we think we have a mechanism that makes them much more abundant than previously thought.

I actually came up with the theory with another colleague in Heidelberg over a coffee more than one year ago!

The theory probably can’t explain the very first black holes but it may provide a mechanism for the vast majority, which would be a very big step forward. We need to poke the theory some more first to see if it holds.

In your opinion, why is your research important?

Humans are the only species we know about that wonder. We have the ability to look out into the universe and try to understand where it is and what it is that we live in – that’s an incredible facility and opportunity to have.

It can be very easy to forget that we live on a small rock orbiting a fairly normal star in a standard galaxy.

We should wonder how that all came about and ask questions about the universe. We don’t know an awful lot of about it, but trying to figure out the right question is something we are very good at – but it takes time.

Finally, I also think it’s important that Ireland shows that it can be a world leader in basic research. Everything doesn’t need to be about an economic return.

What are some of the biggest challenges you face as a researcher in your field?

Ireland has been rather poor at funding basic research and has focused on funding applied research over the last few years. Compared to other similarly sized countries, Ireland is not performing all that well, as we saw with our universities sliding down the rankings.

We don’t appear to have national funding mechanisms in place to support world-class research. It may be getting a little better but, compared to other countries, we’re well down the pecking order. That’s the honest truth.

I’ve seen some metrics that suggest Ireland is a leader in research, but I’d bet if you walk into any university and ask around, most people will lament the current state of affairs.

Is there a good perception of your research among the general public?

People are genuinely very interested in astrophysics and astronomy. We held a space week event in DCU in October of last year and a big crowd turned up.

We had talks on exoplanets, black holes and gravitational waves. The public are really engaged and I was delighted to see so many families and young children there. One little kid even told me I was wrong about something, and he was right – I was delighted!

What are some of the areas of research you’d like to see tackled in the years ahead?

We still don’t understand the physics all that well of how black holes actually accrete gas – it’s a complex problem. Basically, the small-scale physics near the black hole is hard, and that is an area I’d like to spend more time working on in the future.