Paul Stevenson

Favourite Thing: Going to all sorts of exotic places to attend conferences and discuss my work with others. (favourite conference place so far was probably India)

Me and my work

I try to understand how protons and neutrons stick together to make the nuclei that make up almost all the mass of the visible universe.

We understand what everything we see is made from:  Molecules and atoms that are themselves made of electrons orbiting around nuclei.  The nuclei are made of protons and neutrons, but predicting the properties of these nuclei is quite difficult.  The difficulty comes because we are not quite certain about the ways protons and neutrons interact with each other, and also because nuclei are just the wrong size:  They are neither so big that we can ignore the behaviour of individual protons and neutrons nor so small that we can easily solve the relevant equations.  

I create models of the force between protons and neutrons, use these models to simulate things like nuclear fusion, and see how well my simulations compare with what happens when you really take two nuclei in the lab and fire them at each other.  If my calculations agree with experiment I am happy, because I have understood something about the fundamental forces of nature.  If they don’t agree, then I analyse why not and try to improve my model.

Understanding nuclear physics is important for lots of reasons.  All elements heavier than Hydrogen, Helium and Lithium were created in stars.  When the stars died, the heavier elements were spread across the universe to form other stars and solar systems, including ours.  Most of the material that makes up or bodies has been inside a star in the past, and even gone through a supernova.  By looking at the distribution of matter today and understanding the nuclear reactions, we can get a kind of forensic history of the whole universe.  We can do things like this on a more recent scale by looking, for example, at different nuclear isotopes of Oxygen contained in the ice on Greenland.  By analysing these, we can work out the temperature of the Earth back thousands of years, and learn a lot more about climate change.

Though my primary interest is just to understand the way nature works better, and I think that seeking knowledge is an important part of what makes us human, it is important to remember that advances in technology that make the world a better place only come about because people do this kind of basic science.  Without people working in nuclear physics because they were just curious about the nature of the universe, we would not have radiotherapy for cancer treatment, we would not have television, or the world wide web.  I am a scientist, working on understanding things, not a technologist, taking science and turning it into useful devices.  I can be pretty sure that good use will come out of what I do, though.

For more info, see my blog about nuclear physics.

The picture below shows a still from a movie of two nuclei colliding.  The nuclei are isotopes of oxygen and carbon.  Click here (not on the picture) for the full movie.


My Typical Day

ooh, too much to write in one sentence – look at the longer description below!

There really is no typical day.  That’s one of the fun things about my job, but some of the things I typically do are: To catch up on the latest research in nuclear physics by looking at what has been published by other people working in my field.  I talk most days with the PhD students (students who already have one degree and are now working on a research degree) and researchers who work with me so that we can plan what we are going to do calculations to work out.  One thing I am trying to work out with one of my students at the moment is how we can make new chemical elements by colliding heavy nuclei together.  We are working out how to use a cluster of computers to make the calculation go faster.

Having done calculations, I spend some of my time writing it up to send for publication, so that other scientists can find out about it, and also going to present my work at conferences around the world.  The last one I went to was in Bulgaria, and the next one, hopefully, will be in San Fransisco (so I get to travel quite a lot!)

Like all university lecturers, though, my job is not just about researching, but also about teaching the next generation of scientists all the things they need to know to become science researchers, so I spend quite a lot of time preparing lessons and lectures and then giving them, and working with undergraduates on projects (actually the “new elements” calculation project is with a student).  Aside from that I look after the admissions process to the university for physics students, so I look at a lot of the application forms and decide who to invite for interview, and I spend quite a bit of time going to schools to talk about what it’s like to be a scientist and about nuclear physics.

What I'd do with the money

Use it to make a really fantastic touring physics talk

I enjoy going out to schools to talk about some of the interesting, and perhaps surprising, aspects of nuclear physics.  Everyone knows about nuclear power and nuclear weapons, but nuclear physics is used in a lot of medical applications, both in diagnosis and treatment, in climate change studies, in manufacturing, in safety equipment, in space propulsion systems, in understanding the stars, geology, biology, and really just about anywhere.   I’d use the money to buy example pieces of equipment in all these areas, so that I could demonstrate better with real life examples just how useful nuclear physics really is.  Then, when I go to schools and other places to give talks, I would be in a better position to answer the questions like “yes, but what is it useful for?”

My Interview

How would you describe yourself in 3 words?

tall, with hat

Who is your favourite singer or band?

That’s a hard one – there’s so much good music. I’ll go for Galaxie 500, though. They were around in the 80s and have just had their records re-released because there’s still a lot of interest in them. Their music is a wonderful combination of noise and beauty

What is the most fun thing you've done?

Most fun thing ever? There’s 35 years to choose from. Well, I absolutely loved going to theme parks when I was a kid. As an adult, I had an amazing time touring round Iceland and seeing the wonderful and bleak scenery.

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

1) Several clones of me, so I can do all things I’d like to do. 2) a magic jar that would always be full of peanuts whenever I opened it. 3) That I could explain things in such a way as to be understood perfectly first time, no matter how complicated the thing!

What did you want to be after you left school?

A Physicist (though when I was much younger I wanted to be a window cleaner!)

Were you ever in trouble in at school?

Only ever rather mildly. Usually for giving answers to questions that I thought were funny, but the teacher thought were silly.

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

I wrote an online calculator that works out the values of Clebsch-Gordan Coefficients, which are needed by chemists and physicists as part of their calculations. It’s turned out to be surprisingly popular and I keep bumping into people who tell me how useful it is, which is really nice.

Tell us a joke.

What’s brown and sticky? ʞɔıʇs ɐ