Academia · PhD · Science

I passed my viva!

My viva (phd thesis defence/exam thing) was yesterday and I passed!


I met with my examiners at 13:00. The first thing my external examiner said was “I enjoyed reading your thesis, I think the research is interesting and important, and I see no reason why we shouldn’t pass you – I just have a few questions about some details.” My internal examiner agreed with him. I was immediately put at ease and finally started to believe that my viva would be fine. We then started going through my thesis from the beginning. I’d heard that for many candidates, a long time was usually spent on the first two chapters, which tend to include the background information and motivation for the student’s research, the details of which are in the following chapters.

My first chapter was about gravitational waves, why we expected them to exist, the history of attempts to detect them, the things that might cause them, and the noise sources that might make detecting them difficult. Obviously, I also included the fact that gravitational waves were detected last year. My second chapter focused on “thermal noise” one of the main noise sources that make it hard to detect gravitational waves with detectors like LIGO and how reducing the thermal noise level further will make future detection easier.Β My research was mostly to do with the materials you’d need to use if you wanted to run a detector at cryogenic temperatures in order to reduce thermal noise, so this set me up pretty well.

Thermal noise, my most maths-y chapter.

The problem is, like most experimental physicists, I find the theory side pretty hard. I’ve never studied astronomy, so for things like black holes and neutron stars I probably have some knowledge gaps. I’ve never taken a course on general relativity and there’s plenty of maths there that would take me a really long time to master. My chapter on thermal noise was full of equations and, knowing I often make algebra mistakes, I’d carefully annotated a copy of my thesis with the algebra I’d need to derive every equation that appeared. Even so, I had been very nervous about the first two chapters.

So you can imagine my surprise and delight when, after a couple of cursory remarks about the first chapter, my external examiner said, “ok, and then, on page 55…” and I had to interrupt to say, “chapter 3?” and he said, “yes, chapter 3” and went on with his question. They were skipping chapter 2! We’d only spoken about chapter 1 for about 5 minutes! It wasn’t a mistake, they were just happy with the first two chapters andΒ wanted to discuss my research!

I wasn’t about to argue. We spent about 45 minutes on each of the following chapters and while there were a few questions which took me a little while to answer, mostly it was just a discussion. To me, it seemed that my examiners just wanted my thesis to be as good as it could be, that they wanted to help me present my work as well, and as clearly, as possible. As much as their job is to check that I wrote it myself, that I really did the research and that it constitutes an original contribution, I felt like they were already convinced of all of those things when they entered the room.

I no longer have any excuse for my living room to look like this and I’m way happier about that than is technically appropriate

Everyone always says it will be fine. They say you wouldn’t have been allowed to sit a viva if you weren’t ready for one. They say it’s not really a true exam, that it’s open book, that it’s a discussion and that if you get stuck your examiners will help you along. All of that is true. Everyone knows it’s true but it’s also such a big deal that you get nervous about it anyway.

When our discussions were complete I was asked to leave the room for a moment so they could discuss final details and administrative bits and pieces. I was called back in and told I had passed, pending minor corrections, which I would have one month to complete. They apologised for ruining my Christmas, as if passing my viva wasn’t the most wonderful present I could hope to receive. We shook hands and my external examiner went to find a taxi to take him to the airport, while the rest of us moved to the physics building common room, where my friends and colleagues were waiting to open the champagne.

I made quick phone calls to family and then went to join the party.

23 thoughts on “I passed my viva!

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