Position: Former Professor, School of Chemical and Physical Sciences, Victoria University of Wellington.
How do you study things you can’t touch, or even see? As an astrophysicist, those were some of the problems facing Professor Denis Sullivan all the time. To him, the challenge of collecting data from distant parts of the galaxy was all part of the fun. The trick was to get the best quality data possible, to construct the most accurate computer models.
Denis couldn't see planets orbiting other stars, but he could detect the effect they have on their nearby star. He couldn't see directly inside a white dwarf star, but he could collect information from radiation given off at the surface. Mathematics, physics and computer models can help explain what’s going on.
Things that happen in space are often very complex, but we can understand them with physical models that use mathematics to make the concepts concrete. Mathematics is the underlying language of physics, but understanding the physics requires more than simply doing the maths.
“Mathematics makes ideas precise in physics, but really understanding the physics is a real challenge,” said Denis.
This is one of the great attractions of this subject; there is always something more to learn, a deeper insight to achieve. It’s rarely a matter of, oh well, I understand this, let’s move on.
The limits of science
Science is about asking questions as well as making observations. It’s when Denis though about some of the ‘big’ questions in astronomy that he was aware there are some things we may never know about the universe.
Take the question “Is there life elsewhere in the universe?” It’s one of those things most people want to know. Denis found planets around distant stars, but we may never know if they have got life on them.
Denis said that we have found planets orbiting other stars, we are starting to collect information about their atmospheres, and we may one day find planets that could support life
According to Denis, what we can’t do – and it’s unlikely we ever will – is detect life directly, because these extrasolar planets are just so far away that we’ll never visit them.
Mind you, Denis admited that you have to be careful when making predictions like this in science.
Unfortunately Denis passed away at the end of 2019. In the Southern Stars, Journal of the RASNZ June 2020 edition, friends and colleagues remembered him.
This article is based on information current in 2009 and updated in 2021