The ETH Earth Scientist arranges to meet at Hot Pasta, a popular café on Zurich’s Universitätsstrasse. He spends a lot of time at the university, and he needs to get out sometimes to clear his head and chat with colleagues. The Branco Weiss Fellow is full of ideas. But not all of them relate to Earth Sciences. ‘I’m fascinated by discovering bridges across disciplinary boundaries, because they show how all of us are connected in our search for understanding. In particular, the links between sciences, humanities and their ties in all societies needs to be explored and strengthened’ he says, before taking a sip of his coffee and setting his cup down thoughtfully.
Studying Earth’s material balance
Galvez’s scientific research has attracted particular attention recently, as one of his papers was published in the highly respected journal Nature. This research was made possible by a Branco Weiss Fellowship. Fellowships of this kind are awarded to outstanding researchers on an annual basis, and the 32-year-old Frenchman was the recipient of one of nine awards presented last year.
Matthieu’s work aims to understand the physical processes that tie together the history of the Earth and the evolution of life on our planet. ‘Biological evolution has shaped the Earth’s surface,’ he says, ‘but the mechanisms by which biology has sculpted the Earth itself remains mysterious. We do not know how deep inside the Earth this influence can be traced, and whether those conditions are unique to Earth’.
One way this interaction operates is through the exchange of metals and light elements between the Earth’s interior, the atmosphere and ocean. Traces of those interactions are recorded in rocks, some of them are ancient and altered. Minute changes in their composition can reveal a great deal about the changes that our planet went through over time. His work aims to measure and decipher the message of rocks through experiments and computer simulations.
This paper, he explains briefly, concerns specifically the properties and role of aqueous solutions in Earth’s material cycles. Chemical exchanges between the surface and the Earth’s interior take place in areas called subduction zones, where oceanic plates slip beneath continents and sink into the Earth’s mantle, carrying water and other volatiles deep into the planet’s interior, where they are liberated. Working with two colleagues, Galvez investigated the chemical behaviour of these fluids, and examined how sensitive their chemical composition is to variables such as pressure and temperature.
Using novel computer simulations he developed himself, he found that the ionic composition of deep fluids is very sensitive, in particular, to the chemical composition of oceanic rocks, which are themselves sensitive to the chemical state of the atmosphere and oceans at the time of their formation. Those relationships suggest a great variety of chemical feedbacks between the surface and the deep Earth, many of which we need to explore further. He thinks the work opens up new ways for exploring how Earth and life have interacted, and to better understand what makes our planet unique.
Focus on broad horizons
Before working on the chemistry of water inside the Earth, Galvez began his academic career with a thesis on the behaviour of carbon materials at elevated pressure and temperature. ’Earth’s tectonic carbon cycle is complex. It connects all life forms with our planet. His doctoral thesis was focused on this topic.
‘Many people are reluctant to complete a doctoral thesis for fear of being restricted by too specific problems. My experience was, perhaps surprisingly, precisely the opposite,’ the postdoc at ETH Zurich’s Institute of Geochemistry and Petrology says. ‘By concentrating on one field, I actually discovered a variety of links with other subject areas, in a wider search encompassing my topic. That can be a very pleasant experience for someone as curious as I was and still am’. He feels it may be easier to draw a blank if you fail to pay attention to what’s around your main focus.
‘By concentrating on one field, I actually discovered a variety of links with other subject areas, in a wider search encompassing my topic.’
Matthieu Galvez, Branco Weiss Fellow
In fact Matthieu considers it as part of his academic duty to think about the scientific practice in its broader societal context and not only about its content. He thinks that this perspective on science, which would broaden students’ horizons, is missing from most of today’s scientific curricula. ‘It is not all about taking precise measurements, programming algorithms or finding the rules behind order and disorder. ’A scientific career may be more exigent and important than that in many ways’, he says.
A journey through earth
Galvez set a course for a career in research at an early age. ‘My fascination for our planet’s beauty goes back to my childhood,’ he says. His father, a nature-loving driving instructor without a university degree, took Matthieu on countless trips to the countryside, where they used to watch ants working and interacting. ‘For us, it was a form of contemplation. There was nothing scientific about it’ he recalls. ‘I think my parents taught me to admire and question the world. This was simple and very precious.’
For this reason, his decision to study Earth sciences was not an easy one. During his time at high school, he was just as attracted to the humanities as he was to natural sciences. It may have been a gift from his parents that sowed the seeds of his decision: ‘They once offered me a globe, an illuminated one - a beautiful object,’ he recalls. It was this, he says, that kindled his fascination for the Earth, and he later became fascinated by the word ‘geo-logy’ itself. The ethymology of this word instantly resonated with me. I was so thrilled to discover that there was a job reserved for ‘specialist of the planet Earth’ made just for me.’
Inspired by new life
Although he has had to set aside his romantic ideas of life as a geologist as he imagined it in his childhood and adolescence, he remains convinced of his career choice. ‘It was - and still is - the right career for me. I really like to be a ’professional? researcher in the society, I feel free and there are a lot of rewarding experiences in my daily activities.’
Nineteen months ago, the researcher became a father for the first time. This event turned his life upside down. ‘I’m having a few sleepless nights,’ he admits. ‘Life is totally different from before and I want to spend a lot of time with my family.’ Now, with the same enthusiasm he has for the Earth, life and books, he is admiring and helping his child develop and grow, which is ‘by far the most beautiful thing I have ever experienced’. To be present at the birth and observe the start of a new life had a huge impact on him. ‘It was so fascinating, ’geological? in many ways, that I got fascinated by medicine. After all, metabolic reactions are where Earth and Life‘s processes unite.’
Change is the only constant
His coffee has long since gone cold. Almost unnoticed, the restaurant has filled up and lively conversations are underway at neighbouring tables. Galvez takes a last sip. ‘My path had twists and turns,’ he says. ‘I’ve never followed a straight line. I remain mostly driven by my questions, which are constantly changing. Although it can be quite unpredictable, it’s fascinating to see what comes out of it.
Galvez ME, Connolly JAD, Manning CE. Implications for metal and volatile cycles from the pH of subduction zone fluids. Nature 539, 420’424 (2016).