The first direct detection of gravitational waves opened the possibility of mapping the Universe via this new and independent messenger.

We explored the Universe using weak gravitational lensing, a phenomenon that occurs when light from distant galaxies is bent by the gravitational fields of closer cosmic objects, much like how a lens distorts light.

One of the most important correlation functions in physics, especially in cosmology, is the energy density, which describes how much energy is present at each point in spacetime due to matter fields. A key contribution to the energy density of the primordial universe comes from gravitational waves (GWs),…

Promotor: Prof.dr. S. Portegies Zwart

Promotor: K. Kuijken, Co-Promotor: H. Hoekstra

In this work, I explore the creation of new methods that optimize simulations of the gravitational N-body problem. Specifically, I take advantage of the recent popularity of Machine Learning methods to find tools that can suit this problem.

Of all the mass in our Universe, 80% is thought to consist of a hypothetical and invisible substance called dark matter (DM).

In astronomy, the interpration of observations and measurements plays a crucial role: we rely purely and fundamentally on the information that reaches us as observers. And 80% of all matter in the universe is undetectable directly.

In this thesis we study the landscape of gravitational models which modify GR by introducing an additional scalar degree of freedom (d.o.f.) to source Cosmic Acceleration.

‘I could hardly believe my ears when I heard that we had been awarded the Gravitation grant,’ says Berna Güroğlu, professor of the Neuroscience of Social Relations. This grant is awarded by the state, via NWO, to pioneering scientific top research. In terms of grants, this really is something special,…

It's one of the big cosmology debates: the universe is expanding, but how fast exactly? Two available measurements yield different results. Leiden physicist David Harvey adapted an independent third measurement method, using the light warping properties of galaxies predicted by Einstein. He published…

Video interview with Subodh Patil, the new assistant professor in Theoretical Cosmology, about the gravitational waves, hidden universes, music, and whether Dutch, Danish and German fit into one brain.

Leiden University is involved in five new NWO Gravitation projects. Two relate to mental disorder and the remaining three to a healthy lifestyle, the combination of human and artificial intelligence, and the special relationship between plants and microbes.

Three major research projects involving Leiden scientists have been awarded a grant from NWO’s Gravitation Programme. The projects are on innovation processes, organs-on-chips and quantum software.

Leiden scientists and companies receive 1.37 million euros to develop technology for the Einstein Telescope. This underground telescope will measure gravitational waves and must therefore be extremely sensitive. To that end, the consortium conducts research on the damping of vibrations at temperatures…

This thesis investigates the structural evolution and assembly of galaxies since the first few billions years after the big bang.

Three Dutch-Belgian telescopes have started operating at the ESO La Silla Observatory in Chile. This so-called BlackGEM array will scan the southern sky to hunt for cosmic events that produce gravitational waves, such as mergers of neutron stars and black holes. Leiden astronomer Rudolf le Poole is…

At the largest scales, two ingredients dictate the distribution of matter in the Universe. The first is dark matter, acting as an invisible scaffolding held together by gravitational forces.

The European Space Agency (ESA) has approved the proposal for gravitational wave detector LISA. The launch for the space detector is planned in 2034. ‘A dream that comes true,’ says astronomer Elena Maria Rossi.

The project MiCRop receives 20.3 million euros from the Gravitation programme of the Dutch Research Council (NWO). MiCRop will unravel the microbial community around crops. This knowledge will help to develop more sustainable crops that require fewer fertilizers and pesticides. Leiden professors Jos…

The project Hybrid Intelligence receives 19 million euros from the Gravitation programme of the Dutch Research Council (NWO). The consortium consists of six Dutch universities and combines human and artificial intelligence, aiming to amplify human intelligence instead of replacing it. Leiden professors…

How can young people grow up successfully and contribute to the present and future society? The consortium that is researching this will receive 22 million euros within the scope of the Gravitation programme.

The Advanced Nano-electrochemistry Institute Of the Netherlands (ANION) consortium will receive 23.6m euros in Gravitation funding for research on important electrochemical processes for energy transition. An additional four consortia with members from Leiden have also been awarded funding.

Gravitation programme grant Co-applicants Bernet Elzinga en Andrea Evers are two of the captains of the six teams, all led by main applicant Anita Jansen, Maastricht University.

The physical origin of the dozens of stellar-mass binaries, the mergers of which have been detected by the LIGO-Virgo-KAGRA collaboration via gravitational waves, is still unknown.

The ultimate goal of cosmologists is to find a cosmological model able to explain the current observational data.

Leading scientists in the field of the ethics and philosophy of technology are currently revising time-honoured key philosophical concepts such as autonomy, justice and responsibility, as these concepts are being challenged as a result of new technological developments. They receive 17.9 million euros…

Galaxy intrinsic alignments induce a major astrophysical contamination to weak gravitational lensing measurements and need to be modelled and mitigated when extracting cosmological information from such measurements.

The European Space Agency (ESA) has published an interim data release from Gaia, the space telescope mapping out the Milky Way in 3D. The first scientific papers published today reveal half a million stars in the Omega Centauri globular cluster, nearly 400 candidate gravitational lensers and the positions…

Professor Frank den Hollander has been awarded a 10-year grant through the NWO Gravitation program, jointly with colleagues from the University of Amsterdam, the Center for Mathematics and Computer Science in Amsterdam, and the Technical University of Eindhoven.

For centuries astronomers studied the Universe by collecting light. Nowadays, we are living in times of great technological advancements, which allow us to explore our Universe in a new way - though gravitational wave radiation.

Bringing together chemists and physicists to thoroughly investigate how electrochemical processes work on the smallest scale. That is the goal of the new Advanced Nano-electrochemistry Institute of the Netherlands, or ANION for short. The consortium receives a Gravitation funding of 23.6 million euros…

Galaxies form and live inside dark matter haloes. As a consequence, they are exposed to the tidal fields generated by the surrounding matter distribution: this imprints a preferential direction to the galaxy shapes, which leads to a coherent alignment on physically close galaxies, called intrinsic a…

Promotor: Koen Kuijken Co-promotor: Henk Hoekstra

In this thesis, the research focuses on the properties of dark matter and dark matter haloes and how they connect with the galaxies we can observe in the Universe.

Three major cosmology-focused missions are planned for the next decade: the Euclid space telescope, the Vera C. Rubin Observatory in Chile, and the Nancy Grace Roman Space Telescope.

Many astronomers suspect that most of the matter in the universe is invisible. So how can you weigh dark matter if you can't actually see it? Professor Henk Hoekstra is looking for a solution. Inaugural lecture 25 June.

Promotor: Prof.dr. J. Schaye, Co-promotor: Marcello Cacciato

Our research primarily focuses on the early universe and its origins in theories that go beyond the Standard Model of particle physics.

ESA’s Euclid mission is to reveal the dark side of the Universe. But how? Professor of Observational cosmology Henk Hoekstra explains it in his interview with Space Team Europe and Horizon Magazine. He uses enlightening examples such as… a swimming pool! Listen to Henk Hoekstra to understand how Euclid…

What physics controls the properties of quantum matter, such as how electrons flow inside high-temperature superconductors? This question has captivated the physics community and industry for decades, in part due to the great technological potential such materials have, but also because they have resisted…

Welcome to the Hensen Lab! We are a young dynamic experimental research group starting at the Leiden Institute of Physics. Our lab addresses one of the key challenges of modern physics: understanding the interface between quantum mechanics and general relativity.

Improvements of weak gravitational lensing shape measurements are presented and some used for data analysis.

PhD defence

This thesis is dedicated to the exploration of the primordial dark ages: unknown physics during the earliest stages of the Universe’s expansion that have not yet been directly probed by observations. Cosmic inflation is a burst of exponential expansion of space after the “Big Bang”.

Astronomers led by Simon Portegies Zwart used simulations to reconstruct how three stars were ejected from the star cluster R136, 60,000 years ago. The analysis reveals that five stars were involved in the event in the Tarantula Nebula.

We are cosmologists, in other words we use physics to study the Universe, how it started and evolved into the structure that we observe around us.

Top scientists of three Dutch universities are working on software and systems for quantum computers. Researchers of the Leiden Institute of Advanced Computer Science (LIACS) and the Leiden Institute of Physics (LION) are developing new algorithms to make those super computers work. The coming years,…