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. Continue reading

Interview with Daniela Saadeh: winner of the IOP Gravitational Physics Group (GPG) thesis prize

Daniela Saadeh

Daniela Saadeh – UCL Astrophysics Group

CQG is proud to sponsor the IOP Gravitational Physics Group (GPG) thesis prize. This year the prize was awarded to Daniela Saadeh, who we have interviewed below. Congratulations Daniela!

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

A fundamental assumption of the standard model of cosmology is that the large-scale Universe is isotropic – i.e. that its properties are independent of direction. Historically, this concept stemmed from the Copernican Principle, the philosophical statement that we do not occupy a ‘special’ place in the Universe. In physical terms, this idea is converted into the assumption that all positions and directions in the Universe are equivalent, so that no observer is ‘privileged’.

However, assumptions must be tested, especially foundational ones. General relativity – our standard theory of gravity – allows for many ways in which spacetime could be anisotropic: directional symmetry is not fundamentally required. If the Universe were indeed to be anisotropic, we would actually need to carefully revise our understanding (for instance, calculations about its history or content). Making this health check is very important! Continue reading