Arttu Rajantie

Sad to have lost, but it was great fun. Thanks all for your questions and votes. And congratulations, Ceri! You deserved to win.

Favourite Thing: Figuring out from simple laws how complex things (such as the whole universe) work.



I grew up in Finland and went to school there.


BSc, MSc and PhD in Theoretical Physics at University of Helsinki (in Finland)

Work History:

University of Sussex (1998-2000), University of Cambridge (2000-2005), Imperial College (2005-)


Imperial College

Current Job:

Reader in Theoretical Physics

Me and my work

I do research in theoretical cosmology, using our knowledge of particle physics to understand how the universe began, and teach physics to university students.

We are now at a very exciting time in history, when we can finally answer some of the questions about the universe that have been puzzling the mankind for ages. From astronomical observations, we have already learned a lot about the universe and how it began. For example, we know that the universe is expanding and it started with a Big Bang some 13,7 billion years ago.

However, we cannot observe the Big Bang directly, so to learn more about it we need to piece together what happened from observations we have available and from the elementary laws of nature which we have discovered in particle physics experiments. This needs complicated calculations, and the further back in time we want to go, the harder it gets. I am lucky to have access to a big supercomputer called Cosmos, which I use for these calculations (and which also makes a cameo appearance in Lucy Hawking’s “George” books in case you have read them…)

In particular, our observations show that when it was very, very young, the expansion of the universe was accelerating rapidly, and this is why it is so large today. The main thing I try to do in my work is understanding what caused this rapid expansion, which we call “inflation”. Although my own work is purely theoretical, there are some really exciting experiments going on right now, which are going to help us with this. The most important ones are the LHC particle accelerator at CERN, which will tell us more about the laws of particle physics, and the Planck satellite, which is measuring radiation coming from the very early universe. I am therefore sure than in ten years time we’ll know much more about the universe.


My Typical Day

I sit at my desk doing calculations, talk to students and colleagues, give lectures, read and write articles etc.

My job title is “reader”, but it does not mean that I spend all of my time reading stuff. Instead, it is an academic university job which involves research and teaching.

I live in Reading and work in London, so I start my day by taking the train to Paddington. On the train I have time to read and write emails and prepare for the day.

When I get to work, I usually have a meeting with one of my PhD students first. After that, the days vary a lot. My research involves mainly sitting at my desk, doing calculations, thinking about the problem and reading research articles. However, I find it important to talk to other people to hear their views and to know what is going on in cosmology because it is fast-moving field. I talk to my colleagues and go to seminars given by visiting scientists. I also often give seminars about my research at other universities and talk at conferences. The main way to tell others about your research is by writing articles for scientific journals, so I do a lot of that, too.

Part of my job is teaching, so in the term time I often give lectures to students. We are a big department, so the classes can be large, and then preparing the lectures and making them interesting can be a lot of work. However, it is very rewarding to see how the students are learning.

Sometimes I have committee meetings and paperwork, which is not always fun, but which is very important for keeping the department operating smoothly so that we can focus on our research and teaching.

In general, one great thing about being an academic is the freedom and flexibility. I can decide myself what I can work on in my research, and I can do most of my work wherever I want  and at whatever time I want. However, that also means that you have to be quite organised and capable of planning your own work.

What I'd do with the money

I would do a project about the universe with kids at my local primary school.

My Interview

How would you describe yourself in 3 words?

Curious, quiet, stubborn

Who is your favourite singer or band?


What is the most fun thing you've done?

Playing with my kids.

If you had 3 wishes for yourself what would they be? - be honest!

(1) Have a chance to go to space (2) Have the guts to go to space (3) Survive my trip to space

What did you want to be after you left school?

I always wanted to be a scientist. After reading Stephen Hawking’s “A Brief History of Time” when I was 15, I knew I wanted to be a cosmologist.

Were you ever in trouble in at school?


What's the best thing you've done as a scientist?

Organising and chairing a large international conference on particle physics, string theory and cosmology. After months of hard work by the whole team, it was great to see how everything went smoothly. Participants came from all over the world, there were fantastic talks and many interesting discussions. Everyone was having a great time and I’d like to think that a lot of scientific progress was made.

Tell us a joke.

Two protons walk into a black hole.