
Roan Haggar grew up in the British countryside of Kent, known as the Garden of England, where the night skies were dark and the stars innumerable.
Perhaps that’s why, as an astrophysicist with a PhD from the University of Nottingham, he explores the enormity of the universe, and likes to put numbers – enormous numbers – on the phenomena out there. As a member of The Three Hundred Project, a large catalogue of galaxy clusters simulated with physics models, he is measuring scales that boggle even the biggest mind.
When not tallying the universe’s multitudes, he leads public outreach for the Waterloo Centre for Astrophysics, and can often be found clinging by fingers and toes to indoor rocks. He has delivered dozens of public talks, media appearances and exhibits designed to get more people engaged with science.
In this Q&A with FirstPrinciples, Haggar explains why he sees science as an adventure in uncharted territory, and shares the scientific fact that perpetually blows his mind.
FirstPrinciples: What compels you to tackle fundamental questions for which the answers are so elusive?
Roan Haggar: It’s a natural human feeling to want to explore. What’s on the other side of that hill? What’s underneath this rock? Asking the fundamental questions about our universe is the closest most of us can get to exploring beyond the Earth.
The fact that these questions are so difficult to answer is what makes them so exciting.
FP: Why do you focus specifically on astrophysics?

RH: I think most people have looked up at the sky at some point and thought “What’s actually out there?” or “Where did we come from?”
To me, those big, fundamental questions about our existence are the most exciting ones to ask, and astrophysics is the best way to answer them. There are so many beautiful objects in our universe — galaxies, nebulae, the cosmic web — and it’s incredible to me that we can launch telescopes into space to take photographs of these things.
Trying to understand how the laws of physics can create these structures is what really excites me about astrophysics.
FP: What do you find most surprising or amazing about our universe?
RH: The size of our universe constantly blows my mind. Eight planets orbit our Sun, but our galaxy, the Milky Way, contains about 100 billion (one-hundred-thousand-million) other stars just like the Sun. On top of that, we now think there are about one trillion (one-million-million) other galaxies out there. That means our Sun, responsible for all the life we’ve ever known on Earth, is just one out of one-hundred-thousand-million-million-million stars in our universe!
It’s a bit of a misconception that astronomers can actually understand these kinds of numbers, but we really can’t — there’s no-one on Earth who can comprehend just how big that really is.
FP: What keeps you up at night?
RH: How did the universe start? It’s a question that becomes more frustrating the more you think about it!
There’s so much that we know about the early stages of our universe, right back to one trillionth of a second after the Big Bang. But what happened before that? It’s something that feels so close, but also seems so far away. At a point, it almost becomes a philosophical question, and those are much harder to answer.
FP: What discovery or advance do you hope to witness (or be part of) in your lifetime?
RH: Dark matter has to be one of the most incredible discoveries of the past hundred years. Observing the effects of dark matter throughout our universe has given us a pretty good understanding of how much dark matter there is, and what its properties are. But we’ve never seen dark matter directly, and so it’s still a complete mystery what it’s actually made from!
There are a hundred different ideas, ranging from black holes to neutrinos to some new mysterious particle, and there is work going on right now searching for all of these.
Whatever it is, it will totally change our view of physics, and it’s something that I can’t wait for.