I did my undergraduate degree at Aberystwyth University in Wales. I took the astrophysics course, which ran in parallel to the plain physics degree for the first two years, covering all the basics such as mathematical methods, classical mechanics, waves, optics, thermodynamics and so on. In the third year the astrophysics became the main focus, and I took courses on the interior of the Sun, the solar atmosphere, space plasmas, stellar and galactic evolution, and my favourite of all, general relativity (GR) and cosmology.

I took GR in the second semester of my third year. At around the same time, we had to choose the project that we would work on during the fourth, Master’s year of our degree. The majority of the projects offered were in solar physics or condensed matter, the two strong research areas in the physics department at Aberystwyth. Of the two, I preferred solar physics, but having enjoyed the GR and cosmology module so much, I started to wonder if I could study something along those lines instead.

Furthermore, I was also starting to think about PhD applications. I knew that I wanted to do a PhD in cosmology, even if my Master’s project had to be on solar physics. But I wasn’t sure if having a Master’s in the “wrong” field would hinder my PhD applications. So, as I had so often done in the past with programming questions, I turned to Stack Exchange, and asked this question on the Academia section of the site: https://academia.stackexchange.com/q/72289/49043.

I got three excellent answers on the same day, but the one I appreciated the most, and acted on, was this:

The other answers made the point that the exact topic of a Master’s doesn’t matter too much when it comes to applying for PhDs, and in my case certainly wouldn’t be held against me, but Martin Kochanski’s answer went one step further. It made me realise that it was ok to email a few potential supervisors and ask their opinions, and so that’s what I did.

At the time, the only cosmologist I knew was Pedro Ferreira. I’d met him during an open day at Oxford a few years before and spent the intervening time intending to read his book*. He sent me a really nice email, in which he suggested that I find someone to supervise a project remotely — that way I could do what I really wanted, which was study cosmology, and not worry about the topic being at odds with what I wanted to work on during my PhD. He was on sabbatical at the time and too busy to take on a remote student, but gave me a few names to try and contact.

I spent the next six weeks emailing one or two cosmologists at a time, and in each case receiving a polite but understandable refusal. By the time August came around, I decided to have one last throw of the dice before I went on holiday, and emailed Carsten van de Bruck at Sheffield.

To cut a long story short, Carsten enthusiastically agreed to take me on as a remote student and I spent the following year under his guidance, learning all I could about dark energy (specifically quintessence) and teaching myself Python in order to analyse the behaviour of various quintessence models of dark energy. I was awarded the 2017 Breen Prize for best Master’s dissertation in physics for my write-up, Dynamical Models of Dark Energy and Their Background Cosmological Evolution.

The experience of getting my teeth into some real cosmology, coupled with the independence and initiative I’d shown to start the project in the first place undoubtedly helped with my PhD applications. Here I am, in the final few months of my formal education, writing up my PhD thesis in cosmology and preparing to start a postdoc position as soon as I’m done. That’s how asking a question on Stack Exchange turned me into a professional cosmologist.

Postscript

Two unsung heroes of this story are Rudi Winter, in charge of assigning Master’s projects at Aberystwyth, and Xing Li, who taught me GR and cosmology. Without Rudi’s willingness to allow me to be supervised remotely, and Xing’s agreement to act as a second, local supervisor to ensure everything went smoothly, this story would probably have turned out very differently indeed.

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* It’s called The State of the Universe. Seven years, a Master’s degree in astrophysics and most of a PhD in cosmology later, I still haven’t read it.