Anne Green

Understanding what the Universe is made of.

By observing stars and galaxies, we've deduced that most of the matter in the Universe is invisible. It also has to be exotic-some new particle or object that we've not yet discovered. Particle Physicists have some good ideas about what this dark matter could be and are carrying out experiments to detect it. As a theoretical physicist, I work closely with experimentalists and astronomers. I help them design their experiments/observations, make predictions for what they should see and use their results to probe the properties of dark matter.

I enjoy doing maths, but wanted to do maths for a reason, and in my teens I became fascinated by cosmology, the scientific study of the evolution and contents of the Universe.

Unfortunately I’m at a career stage where I don’t very often get to do research myself on a day-to-day basis. But when I do, I do calculations, either analytical (using pen and paper) or numerical (writing code). Plus reading papers and watching talks, to try and keep up to date with other people’s research. The disadvantage of working at the intersection between various sub-fields (astrophysics, particle physics, theory, observation and experiment) is that there’s a lot to keep up with.

I like the fact that it brings together different branches of physics (in particular astrophysics and particle physics) to answer a big fundamental question.

The big one is finding time to focus on research. I’m attempting to address this by trying to put aside blocks of time, and also saying No more often (as a woman in a male-dominated field I get a lot of requests to serve on panels, give talks etc.) . However this is very much an ongoing challenge.

It’s not that recent, but I showed that if the dark matter is made of Weakly Interacting Massive Particles (or WIMPs for short) the first objects to form in the Universe would weigh roughly the same as the Earth. And that these objects could have important observational and experimental signatures. This has led to lots of work studying the formation and evolution of the first, smallest dark matter structures to form, not just for WIMPs but for other dark matter candidates as well.

I’d be really happy if something I’ve done contributes to the discovery of the nature of dark matter.

I currently teach our 3rd year ‘Introduction to Cosmology’ option module, which is a great opportunity to tell students about not just my own research, but recent results in the field of cosmology as a whole. This year that included the ‘Hubble tension’, a discrepancy between different types of measurements of the expansion speed of the Universe, which might be a sign of interesting and unexpected new Physics. I also supervise 3rd and 4th year projects related to my research.

I was fortunate to have several postdoctoral fellowships which allowed me to work on (more or less) whatever I wanted. So I’d tell myself to enjoy having the freedom (and time) to explore whatever caught my interest. I’d also advise much younger me to think much more carefully about what field I wanted to work in. Theoretical physics appealed to me because of its reputation for being hard. However I really enjoy being outdoors and travelling, so there might well have been other branches of science that would have suited me better (e.g. geology).