Exploring the invisible universe: An interview with Licia Verde MAE#
From childhood wonder to cosmic mysteries, Licia Verde discusses dark matter, dark energy, and why discovery is as much about the journey as the destination.
About Licia Verde MAE#
Professor Licia Verde MAE is a leading cosmologist renowned for her work uncovering the universe’s hidden components – dark matter, dark energy, and its large-scale structure. Her research has propelled major advances in cosmology, from pioneering statistical methods that relate galaxy surveys to dark matter, to contributing key insights to NASA’s WMAP mission. Currently, she is ICREA Professor at the Institute of Cosmos Sciences, University of Barcelona.
Professor Verde has received numerous accolades, including the 2012 Gruber Cosmology Prize, the 2018 Breakthrough Prize (with the WMAP team), and the 2024 Medal of the Spanish Royal Physics Society
She was elected as a Member of Academia Europaea in 2025. At the 2025 Building Bridges Annual Conference, she will deliver a plenary speech titled Cosmology.
Read the interview#
What first sparked your curiosity about the universe and made you want to understand how it works?
It took me a while, however, to understand that math had to become my friend if I wanted to go beyond the surface in exploring space, the universe, and how it all works. In fact, it wasn’t until I read Galileo – mostly as a literature assignment – that it truly clicked.
It also helped that, during the 1970s, there was a great fascination with physics, and documentaries about physics were shown in prime-time television slots. I could follow those too, and my parents were patient enough to indulge my extravagant curiosity about physics and astronomy.
I was also fortunate to have very good and inspiring teachers, even though I first pursued classical studies before “seeing the light” and deciding to study physics.”
Your research focuses on what makes up most of the universe, including dark matter and dark energy- can you explain what these mysterious components are and how they influence the cosmos we see around us?
However, dark matter, to a good approximation, interacts only gravitationally. It does not shine and does not feel electromagnetic interactions. When I clap my hands, my hands clap (d’oh). Even though they are made of atoms – and atoms are mostly empty, with tiny nuclei and electrons far away from them – my hands still collide because electromagnetic forces make them do so. If my hands were made of dark matter, I could not clap; they would simply pass through each other.
The effects of dark matter are gravitational. We see dark matter’s gravitational pull on luminous matter, and we see its effect on space-time. As Einstein’s general relativity predicts, mass deforms space-time. From all this, we know there’s a lot of mass out there that cannot be accounted for by the atoms we know exist.
Dark energy, on the other hand, is something completely different. If dark energy were chocolate, then you could put it in a box, and if you were to double the volume of the box, you would get double the chocolate. But, alas, it is not chocolate. It is energy associated with the vacuum. Now it makes (some) sense – if you put nothing in a box and then double the volume of the box, you get twice nothing.
As counterintuitive as it seems, in the form of a cosmological constant, this strange thing was actually introduced by Einstein as a constant term in his equations of general relativity – by hand. His newly developed theory of gravity predicted an unstable universe. But since the universe appeared old and unchanging, it seemed it had to be stable and static – hence the additional term. It turns out that although the universe is not static, Einstein was still correct in adding that term. The universe is undergoing accelerated expansion.
Normal matter, radiation, or even dark matter cannot drive such acceleration. You wouldn’t expect to throw a ball into the air and have it suddenly accelerate upward as if propelled by a rocket. Well, dark energy sort of behaves like that. Its effect is seen as the accelerated expansion of the universe. Galaxies, on average, are running away from each other at an ever-increasing pace (that’s the 2011 Nobel Prize). It also has other, subtler effects, as it influences the history and evolution of structures in the universe.
In terms of structure growth, dark matter accelerates clustering, while dark energy slows it down – a bit like a tug-of-war. Dark matter seemed to be winning in the earlier phases, when the universe was significantly younger; later, dark energy started to win."
When we chart the positions and motions of galaxies, what hidden stories do those patterns tell us about dark matter, the universe’s shape, or its evolution?
What keeps you motivated to study questions that may never have definitive answers, and how do you stay excited about that kind of challenge?
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