Winner of the 2018 IOP Gravitational Physics Group (GPG) thesis prize: Dr Viraj A A Sanghai

Can you tell us a little bit about the work in your thesis?

One of the challenges of modern cosmology is to interpret observations in a consistent and model-independent way. There are several assumptions in interpreting cosmological/astrophysical data. For example, it is often assumed that Einstein’s theory of gravity is the correct theory of gravity. Furthermore, fundamental to cosmology is the assumption that the universe is homogeneous and isotropic on the largest scales and hence, this is the correct starting point to interpret cosmological data. To test these assumptions, approaches are needed, which work in a model-independent way. Broadly speaking, my thesis addresses these questions.

Thinking back, what was the most interesting thing that happened during your PhD?


Dr Viraj A A Sanghai is a postdoctoral fellow working on theoretical cosmology at Dalhousie University in Halifax, Canada

The most interesting thing that happened during my PhD was the discovery of gravitational waves by LIGO, due to the merging of two black holes. This opened up a new avenue into testing Einstein’s theory of gravity and started the new field of gravitational wave astronomy. Before this, all our astronomical observations relied on electromagnetic radiation. This discovery is helping us to have a deeper understanding of our Universe. Consequently, the Nobel Prize in Physics was awarded for this discovery.

What are you working on now, and what’s next?

A lot of the research during my PhD was theoretical. Currently, I’m working on testing Einstein’s theory and its alternatives by linking theory to cosmological observations. It is a truly exciting time for gravitational physics and cosmology. In the next few years, there are several observations that are going to probe new regions of the Universe and collect higher precision data. Hopefully this will help to significantly further our understanding of the Universe.

What motivated you to pursue physics and theoretical cosmology in particular?

The reason I chose to get into theoretical and observational physics is that it allows us to push the boundaries of everything we know. That is still my favourite part about it. I hope the research done by myself and my colleagues can make a difference to our understanding of the Universe and one day, may even lead to us changing our perception of reality.

For cosmology, if Einstein’s theory of gravity is correct, we potentially don’t know what 95% of the Universe is made up of. If not, we need to look at alternatives to Einstein’s theory. Testing and understanding Einstein’s theory and its alternatives in cosmology is what drew me to theoretical cosmology.

What’s been the most rewarding moment of your career so far?

I would have to say it was one of those eureka moments during the 3rd year of my PhD. I had spent over a year trying to solve a particular problem, thinking about it day and night. Eventually, the solution just came to me and led to me finishing a project, which was a major part of my PhD thesis.

What’s been the most difficult moment of your career so far?

The most difficult moment during my career was towards the end of my PhD. I had just returned from a cosmology conference in South Africa and was about to begin writing my PhD thesis when I fell terribly ill. I couldn’t work for a couple of months and my PhD funding ended during that time. When I recovered, I still had a few months to finish my PhD, and fortunately it all worked out in the end. One of the reasons it worked out was because I had great support from my family, friends and PhD supervisors, Dr Timothy Clifton and Dr Karim Malik.

What advice would give to young scientists?

Looking back at my own experiences, there are a few pieces of advice I would give to young scientists. Firstly, whether you are an undergraduate, Masters’ or PhD student, everyone deals with self-doubt at some stage. All I would say is that no matter what stage you’re at, you are good enough to be where you are and good enough to overcome all the obstacles that will come your way. Secondly, in the difficult moments, speak to someone. Find someone you’re comfortable talking to, whether it be your family, your friends or your supervisors. Lastly, you are not meant to know everything. Don’t be afraid to ask questions. As Socrates suggested, ‘The more I know, the more I realize I know nothing’.

And finally, what interests you outside of science?

I love my sports. I particularly enjoy football, cricket and Taekwondo. I also enjoy long distance running. During my PhD, I ran the London marathon twice for the charity PSPA.