Cora, Germany

10 Questions with Cora Uhlemann


Cora Uhlemann, 27, from Germany is a Postdoc at the Utrecht University in the Netherlands.

Her field of work is cosmic structure formation, the quest to physically understand and model the emergence of the cosmic web.

Cora is a participant of the 66th Lindau Nobel Laureate Meeting which is dedicated to the field of physics in 2016.

Enjoy the interview with Cora and get inspired:

  1. What inspired you to pursue a career in physics / STEM?

I’ve been always interested in sciences in school, although there was no clear preference for either one of them until the senior classes. I think what really encouraged me to study physics was the enthusiasm of my teacher who was very passionate about physics and explaining phenomena in nature. I still remember him asking questions like „What does it tell us?“ and „Why is that?“. While completing high school, I did an interdisciplinary project about deterministic chaos and some of its mathematical and physical aspects which finally convinced me that physics is what I want to go for. Besides that, I have to say that both my parents studied physics and my sister engineering, so I am pretty sure I ingested part of my inspiration from my family.

  1. Who are your role models?

I am not sure that I can identify a particular role model I am emulating, although I do look up to many great scientists from the past and present. I think that I simply want to become a better version of myself rather than a lesser version of somebody else.

  1. How did you get to where you are in your career path?

After finishing high school in 2007, I started studying Physics in the Diploma program at the Technical University of Munich and later also enrolled in the Bachelor course for Mathematics. During my studies, I got to know about the joint Elite-Master program for ‚Theoretical and Mathematical Physics‘ at the LMU Munich which I entered in 2010. The next two years, I was very busy with taking courses, studying and graduating in the three different programs which I completed in 2012. After already having done my Master and Diploma thesis with Stefan Hofmann in the Cosmology group at LMU, I started there as a PhD student supported by the Excellence Cluster Universe. Since then I am working on different aspects of the large scale structure of the universe, the skeleton of the cosmos along which galaxies are aligned. After finishing my PhD last summer and being on a short research visit at the Institute for Astrophysics (IAP) in Paris, I started my PostDoc in October 2015 in the group of Enrico Pajer at the University of Utrecht.

  1. What is the coolest project you have worked on and why?

In fact, I have currently two projects which I am very excited about. But I guess it is only natural to find the things you are currently working on the best ones ever. Both projects are about the large scale structure of the universe which is shaped by dark matter. Dark matter can be viewed as a huge collection of particles moving slowly and interacting purely gravitationally. Thanks to these properties, we can describe dark matter in terms of a distribution function that lives in phase space, the space spanned by positions and momenta of the particles. We even know the equations governing its time evolution but in general they are really complicated to solve. This is because gravity causes small accumulations of matter to attract more and more matter and hence to grow quickly.

The first project is about dark matter dynamics and was practically the first idea I pursued during my PhD. Here we want to better understand the formation of gravitationally bound structures of dark matter. Those so-called halos are vital for the evolution of the Universe because they provide the environment for galaxy formation. As long as the matter accumulations are still small, we can treat dark matter as a fluid and solve the equations with perturbation theory. But when densities become sizeable, we have to rely on simulations that solve the dynamics of a huge set of particles numerically. Intriguingly, there is another way to approach the problem which relies on the correspondence principle stating that classical physics can be obtained from quantum mechanics as a limiting case. Hence, we can connect the classical dark matter distribution function in phase space to a certain wave function living in position space. This is interesting, because we can connect the wave function to the simple fluid picture we had for the beginning of the time evolution. But now we are also able to go all the way into the regime of halo formation! For the future this method can be beneficial in two ways: first, as an alternative numerical method that focuses on the distribution function rather than particles and second, as a starting point to develop new analytical methods that can reach into the regime that is so far only accessible to simulations.

The second project is about dark matter statistics and has been started less than a year ago. Here we are interested in describing the statistical properties of dark matter after it has formed bound structures and was populated by galaxies. The distribution of matter and galaxies that we observe today with giant telescopes is our window into the Universe. To extract information about its properties, we have to face the problem of solving the gravitational dynamics all the way from the initial small perturbations to today. If we restrict ourselves to a special observable given as densities-in-spheres, we can take advantage of a symmetric special case of gravitational evolution which admits a full analytical solution. The picture that spherical collapse gives to the most likely way of evolution for averaged densities and some further approximations allow us to predict the statistics of densities-in-spheres from first principles. Since the predictions have been shown to be in excellent agreement with numerical simulations so far, it opens up the possibility to use this approach in the analysis of cosmological surveys. Therefore, the next steps will be aimed at making our approach ready for being applied to realistic data and further exploiting its potential to extract cosmological information.

I am thrilled that I will get the opportunity to present both ideas during this year’s Nobel Laureate meeting, the first during the Bavarian evening and the second in the Astrophysics Master Class held by Brian Schmidt.

  1. What’s a time you felt immense pride in yourself / your work?

One of the cool projects I just mentioned was actually a core part of my PhD thesis for which I got the PhD Award of the Excellence Cluster Universe. I felt very proud and encouraged because I was working quite independently during my PhD, which I experienced as a great opportunity but also a challenge. I am very thankful to my supervisor Stefan Hofmann for placing confidence in me and supporting me on my way of becoming a scientist.

  1. What is a “day in the life” of Cora like?

What I appreciate a lot in a the ‘science lifestyle’ is the degree of freedom and variety. For me, one pleasant part is not being forced to start working early, because I am certainly not a morning person. Besides that, how my day is like really depends on what I am doing currently, so let’s describe at least three typical days:

At a conference the whole day is packed with listening to talks, learning new things and interacting with all the other scientists to gain understanding and foster new ideas. Besides that it is simply getting in touch with the community and sometimes even like a reunion of peers who are usually scattered all over the world. During those days one really feels like living in a science bubble, which is extremely inspiring, but also stimulates the urge to finally sit down and work out those new ideas coming up. So, some days I am just quietly sitting in my office, all-immersed in doing some calculation, trying to solve a problem, testing predictions against simulations or looking for interesting reads. On other days, when kicking off or wrapping up a project (or finishing the paper) there is very active discussion among the collaborators, sometimes like a roller coaster between understanding or questioning everything until eventually progress is made. All in all, every day has its own appeal and challenges, and without actually hitting a wall you will never know if you bounce back or break through.

  1. What are you seeking to accomplish in your career?

First of all, I wish to contribute to improving our understanding of the Universe and finding new ways of thinking about the world. Personally, I thrive on the feeling of exploring some aspect of nature which is what drives me to do science. Therefore, I am seeking the freedom to pursue my own ideas and the possibility to make an impact on science. I like to find new ways of approaching old problems or to rediscover existing knowledge to apply it to new questions. While I currently appreciate the possibility to focus entirely on doing research myself, I also want to start taking up more responsibility in the near future, for example by starting a junior research group. I would very much like to work with young people, inspire and get inspired, bring them into contact with science, encourage their curiosity and accompany them on their way of growing independent.

  1. What do you like to do when you’re not doing research?

In 2009, I became active in the young division of the German Physical Society (jDPG within the DPG,, one of the world’s largest physics societies. The jDPG has captivated me ever since as a unique network of enthusiastic young physicists who are full of new ideas and eager to put them into practice. This year we will be celebrating our tenth anniversary with a ‘Long live physics’ conference in Dresden.

I first got involved in the jDPG by developing a program for motivating high school students to become active in physics. In particular, we founded the physics magazine ‚Detektor’ ( which is not only for but also made by high school students and allows them to share their knowledge and passion for physics. After being a board member for school-related program in the jDPG for several years, I served as its president and represented young scientists within the DPG from 2013 to 2014. For the International Year of Light 2015, I also initiated a Winter School on Gravity and Light together with Frederic P. Schuller and the support of the Wilhelm and Else Heraeus foundation. Held in celebration of 100 years of general relativity and 50 years since the discovery of the cosmic microwave background, this school gave 50 motivated students from all over the world the possibility to learn gravitational physics from the basics to the research frontier. So overall, I like being active in the development of new programs and the organization of large-scale events. Because I am slowly but surely growing a bit too old for the jDPG (at least when it comes to academic age), I am becoming more active in the DPG as a whole to continue my engagement for physics and to give something back to the community that played such an important role in my personal development.

Besides that, I like traveling and exploring new places, for which conferences abroad often provide the perfect opportunity. Now that I am living in the Netherlands for two years while doing my PostDoc here, I also like to visit less well-known places to grasp more about the Dutch culture and history as well as learning the language.


  1. What advice do you have for other women interested in physics / STEM?

I feel like I don’t have specific advice but rather universal encouragement: Simply follow your interests and strive to achieve your own goals. Find people who don’t push you around but forward and then push through yourself. Explore, enjoy and make yourself comfortable outside your current comfort zone. (But be careful, this advice actually works for virtually everybody, no matter what background or gender.)

  1. In your opinion, what will be the next great breakthrough in physics research?

Let’s not make it about opinion but rather about hope: I hope that the next great breakthrough will be direct evidence for dark matter, a yet-unknown type of matter that is theorized to be responsible for the growth of structures in our Universe and hence our very existence. Despite its unknown particle nature, dark matter is a beautifully consistent and conceptually simple theoretical concept and has become an indispensable part of our cosmological standard model. Therefore, finding a concrete hint to a particle candidate would mean an immense leap forward to unite particle physics and cosmology.

What should be done to increase the number of female profs of physics?

The most crude answer to that would be to simply hire more female profs in physics, such as me in a couple of years. 😉 I think that this answer contains some truth, which is that we certainly need to hire more young scientists as professors to increase that number. In general, we have to provide long-term perspectives for researchers with programs that are backed by real tenure-track systems instead of vague promises. Science is driven by the researchers’ dedication and can certainly provide a great deal of purpose in life, but also asks a fair amount of devotion. Right now, knowing about the precarious situation when it comes to long-term positions, makes it very hard to go all-in for science, which is however exactly what is required to have a shot at all. While all this applies to all young scientists equally, I think that women are especially affected by being more risk-averse and less likely to bet on the chance of getting one of the highly coveted tenured positions in due course.


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