I want to share with you my journey towards obtaining a PhD position. By showing you the ups, downs, motivations and doubts that I encountered along the way I hope that I can help fellow students in making their decision as to whether to continue in academia or not after their undergraduate studies. Let me add a disclaimer here: this is a reflection of my personal experiences and the conclusions I derived from them. I highly recommend asking other PhD students or your current supervisor or student mentor for their perspectives on this issue too.

My academic interests

In January 2022, I finished writing my joint Master’s thesis in theoretical physics and mathematics. It was a project in cosmology involving a new model for contaminating effects in weak lensing experiments, which are a very important probe into the history of our Universe. In short, Einstein’s theory of General Relativity tells us that massive objects can bend light rays as they travel past them, thus acting like a lens. If the light sources are distant galaxies and the lens consists of matter between us and the source, we can infer properties of the matter distribution from the lensed image. This allows us to map out the matter distribution of the universe, which also contains information about its expansion history.

As these experiments become increasingly precise, the theoretical models describing these distortions necessarily become more complex. Computing the predictions of the model I considered in an accurate and efficient way is a serious numerical challenge, leading to interesting applications of many mathematical concepts. For example, the predictions require the calculation of integrals of rapidly varying functions over three-dimensional space. This can be done by decomposing the functions as sums of simpler basis functions and computing the integral over the basis functions in a quick way, say by using an exact analytic expression. Provided that the analytic expression is simple enough and the decomposition is not too slow, this idea can make the computation a lot faster.

I was drawn to cosmology because it looks for answers to big, daunting questions. How did we get here? What is our ultimate fate? The idea of contributing to this endeavor really attracted me. Cosmology is a quickly evolving branch of physics and it is related to many areas in mathematics, so writing a thesis in this topic felt like a great opportunity for me to put all that I had learned during my studies into practice.

Is a PhD right for me?

I would describe myself as someone with quite diverse interests, even though I also devote some of my free time to learning about physics or math. However, I am aware that doing a PhD requires a huge amount of time and effort put into a rather specific topic. During my master’s, I knew some people who were doing PhD’s in physics or math and I was also gathering information about academic lifestyle and its pros and cons through the internet. In particular, I spent a lot of hours reading about people’s struggles in the academic workplace on a forum called Academia StackExchange (on a side note, this forum is also a great place to learn about practicing workplace ethics and scientific integrity). This source mainly gave me an idea of the possible downsides of life in academia: the work pressure is very high; you could potentially spend a long time away from your family and friends; and you could become isolated, because if you are stuck in your project, no one has an answer cut out for you. Scientific research is about addressing open questions, and it can be very difficult to find the right approach to tackling them.

This last point also ties into another reason for my initial hesitation towards doing a PhD specifically in theoretical physics or pure mathematics (brace yourself for a philosophical tangent). What exactly would be the value of my work? Even if I myself am convinced that it is relevant and meaningful to pursue knowledge ‘merely’ for the sake of it, I couldn’t help but wonder if perhaps another career path would be more justified. I know this might sound arbitrary, and you would be right to remark that my life choices should not depend too much on the external validation I may or may not get for making them, but I still have trouble dismissing this thought entirely.

So, what’s there to gain? I think the primary motivator for doing a PhD must be the intrinsic desire for a deeper understanding of the subject you are working on, regardless of why it might be useful to others, society, or to yourself in the long term. If you have this drive, I am convinced that doing a PhD can be a rewarding experience of self-growth and independence unlike anything else. I had noticed this drive to be present in the PhD students I knew, and it seemed to be essential to their persistence. It didn’t take me very long to find out during the course of my thesis that I was really passionate about this line of research and liked spending time on it. I found myself reading about related topics in my free time, and I enjoyed participating in discussions in seminars and journal clubs. I was also progressing well and became increasingly confident that what I did was valuable and meaningful, so I gravitated towards the option of doing a PhD. Besides, I have always enjoyed spending time at university, whether it was for my own studies or for my job as a teaching assistant, and I liked the thought of staying in such an inspiring environment.

Because of the downsides I listed earlier, I decided I first wanted to look for positions in physics in the Netherlands. I have built up a lot of social connections here, and it would currently be best for my professional development not to have to start this at a place far away from home. Luckily for me, it turned out I didn’t need to look further, and I was able to obtain a position in cosmology in Utrecht.

Needless to say, I was over the moon when I heard that my application was accepted. I can think of a few aspects of a PhD I am very eager to experience. Some because I see them as potential pitfalls: could it be that I lose interest in the topic after all? Will I be able to balance my working ambitions and social life? But most importantly, and on a more positive note: what does it feel like to be part of a collective of like-minded people pushing the boundaries of human knowledge? What are the biggest challenges that lie ahead and how could they be conquered? From a more down-to-earth perspective, I’m really looking forward to publishing my first paper, which I can start writing pretty much right away as it will be about the results of my thesis. Lastly, being a teaching assistant for a master’s course would also be a new challenge for me that I’m eager to take on!

My advice to other students

At the start of the final year of my master’s programme, I was still not completely sure whether pursuing a PhD was the right choice for me. I had been entertaining the idea for a long time, but eventually I figured out that the best way to gauge if this marriage was to be successful was to simply start working on my thesis and see if I enjoyed it. I would strongly recommend this to anybody. Think of your master’s thesis as some kind of extended job interview for a potential PhD. A job interview goes both ways: not only does your supervisor get a sense as to whether you could be a good fit for academic research, but you also experience firsthand what it’s like to do independent research. This is very different from coursework.

That is not to say your coursework is irrelevant by any means. Obtaining a PhD position is a very competitive task, and good grades can really help you towards that goal. Moreover, if you don’t like studying course material on a subject anymore, then you won’t enjoy doing a PhD in it either. This was the case for me with pure mathematics like geometry and topology. I just lost interest in it as the courses got more advanced, and that was it. My point here is that it is crucial to figure out what you think is worth spending four years of your life on and what isn’t. Try to avoid tricking yourself into thinking you `must’ pursue a PhD, or that `any PhD beats a job in industry’.

On a final and more practical note: once you have decided you want to pursue a PhD, tell your supervisor about it! The application process can be a bit of a zoo and varies greatly from place to place. If you are reading this and would like to know more about my path towards a PhD, you can also reach me at t.j.m.bakx@uu.nl.

Article by Thomas Bakx (MSc in Mathematical Sciences and Theoretical Physics at Utrecht University, the Netherlands.)