Dr. N.C.M. (Niels) Martens

Buys Ballotgebouw
Princetonplein 5
Kamer 3.11
3584 CC Utrecht

Dr. N.C.M. (Niels) Martens

Assistant Professor
History and Philosophy of Science

Philosopher of physics, especially astronomy and cosmology.


Free digital book available until the 12th of March.


Research Interests

My research interests within philosophy of physics, metaphysics and philosophy of science focus on astronomy & cosmology (especially dark matter, dark energy & black holes), symmetries, physical quantities, spacetime & gravity, and the epistemology of scientific collaborations.

Research Group

Our Utrecht Philosophy of Astronomy & Cosmology Research Group (UPAC) consists of philosophers of physics and physicists focusing on modern astronomy, astrophysics & cosmology. All information can be found on our webpage.

We organise a weekly colloquium (hybrid), alternating between a speaker, a reading group session and a work-in-progress session. It is possible to sign up for the UPAC Colloquium Mailing List here (please check your spam folder for an email with a confirmation link to complete the subscription process).

We are open to supporting PostDoc applications (e.g. Veni & Marie Curie), PhD applications (e.g. NWO Lerarenbeurs & Mosaic 2.0), Visiting Fellowship Applications (e.g. Descartes Fellowship, EPSA Fellowship & ERC Visiting Fellowship) and internships (e.g. Erasmus+ or HPS Master Communication Profile) within the Utrecht Philosophy of Astronomy & Cosmology (UPAC) Research Group. Please contact us at n.c.m.martens@uu.nl.

Current Projects

As of 2023, I am the PI of a five-year ERC project on philosophy of astronomy & cosmology, "COSMO-MASTER"  (Philosophy of COSMOlogy: Matter And SpaceTime ERadicated).

I am also one of the philosophy co-leads of the ngEHT collaboration, focusing on the social epistemology and governance structure of this collaboration of 300+ astronomers, engineers, philosophers, historians & sociologists attempting to record the first ever high-quality video of a black hole. Check out our white paper (or see here for the highlights). This is the first time that the Key Science Goals of a large astrophysics collaboration include contributions from scholars from the social sciences and humanities.

Moreover, I am a member of the St. Andrews - Bonn Gravitational Constant Network and the COSMOS History & Philosophy of Cosmology Network, faculty affiliate at Harvard's Black Hole Initiative, and an associate member of the Lichtenberg Group for History and Philosophy of Physics

Previous Projects (Selection)

Dark Matter

The philosophy of dark matter is a young but rapidly growing field. I was managing guest editor of the first-ever special issue on the philosophy of dark matter and its main alternative, modified gravity—see the editorial of the special issue for an overview of research questions within this novel field of expertise.

Dark matter provides an interesting case study for scientific realism.

I am fascinated by the tense relationship between the dark matter and modified gravity communities. I believe that there are less obstacles towards a fruitful collaboration between these two approaches than is typically believed by either of these camps. For starters, the approaches are not always mutually exclusive, as some theories can be both dark matter and a modification of gravity. A large range of philosophical interpretations opens up in the context of such hybrid theories. Moreover, although each research programme seems to have a different standard of success, by supposedly favouring different types of explanations, the reality is much less black-and-white than it may seem.

Dimensional Magnitudes in Physics

Sciences such as physics, chemistry and biology are replete with properties that are quantitative—they come in degrees. Moreover, these physical magnitudes are often dimensional—they are represented by a number times a unit. Does this mean that only magnitude ratios are what matters for physical reliaty, or is there a need for absolute magnitudes over and beyond these ratios? If all masses in the universe would suddenly double, would we notice a difference? Are such scaling transformations a symmetry of our world?

I defend absolutism about mass (at least in the context of Newtonian Gravity), the view that the world includes absolute Newtonian masses that underlie mass ratios. I tried my best to develop better versions of the opposing view, "comparativism", via a Humeanist and Machian approach, but find that these views are still wanting.

Could we eliminate mass altogether by substituting it for spatiotemporal magnitudes? No!

With James Read I discuss the broader methodology that is at play in the symmetry-to-(un)reality inferences that underlie such debates. 

A book on these topics has just been published within the Elements in Philosophy of Physics Series by Cambridge University Press.

Short Biography

Previously, I was a Marie Curie Fellow at Utrecht University, working on the philosophy of dark energy, and a Postdoctoral Researcher in Philosophy of Physics within the interdisciplinary research unit 'Epistemology of the LHC', located at the University of Bonn, Germany, in the Lichtenberg Group for History and Philosophy of Physics, and at RWTH Aachen University, in the Institute for Theoretical Particle Physics and Cosmology. We (still) investigate philosophical aspects of the Dark Matter vs Modified Gravity debate. 

My DPhil (=PhD) thesis was accepted in 2017, after being supervised by Oliver Pooley, David Wallace and Adam Caulton whilst I was a member of Magdalen College (University of Oxford). It discusses what it means for a physical magnitude to be dimensionful. Before that I did an MSt in Philosophy of Physics, also at Magdalen College, and before that a BSc and MSc in Theoretical Physics and a BA in Philosophy of Physics at the University of Groningen. My Linnemann number is 2.