Interview : Prof Alfonso Aragón-Salamanca

NSB was hugely chuffed to have the opportunity to interview Alfonso Aragón-Salamanca recently. As Professor of Astronomy at the University of Nottingham, Alfonso certainly knows his astronomical onions and it was great to able to take advantage of his expertise to learn a little more about how the Universe works.

The interview covered topics as diverse as galaxy formation; what makes a good physicist; and the British sense of humour.

All the very best bits have been transcribed for you below. Enjoy!


NSB : To start with, could you tell us a little about how you got an interest in astronomy.

Alfonso : I was always very interested in science, I was good at science and maths at school. To be honest, I always liked any science, finding out new things. I think I could just as easily have been a biologist or a geologist or chemist - finding out things that people don’t know.

I ended up doing astronomy because I was good at physics and had a very good physics teacher and I started doing a degree in Physics in Madrid, back in Spain and then out of the options that I could take in physics, astronomy sounded quite exciting. From there I graduated and got the opportunity of doing a Phd in Astronomy at Durham in 1988. After that I worked in Durham for a while and then I moved to Cambridge and worked there for five years. Then, back in 1999, the Department of Physics at the University of Nottingham decided to expand into astronomy and hired five of us that formed the group which has been going ever since. . . Now the group is of the order of 35-40 people. We have been very successful, very good at attracting both students and researchers and from being a completely new group we are now one of the strongest groups in the country in our field of research which is extra-galactic astronomy.

The University of Nottingham has some buildings that Prince Charles would approve of . . .

. . . and some that he probably wouldn’t

NSB: Regarding the funding for astronomy, where there is no immediate application, where do you get the funding for your research and so on?

Alfonso : The teaching comes as part of the funding for teaching of science and physics. This has traditionally come mostly from the Government but is coming more and more from the student fees. For the research side, it is mostly public money through the Governments and European research councils and the Royal Society for “blue sky science”, science that doesn’t have any immediate application but you have to remember that two centuries ago, electricity was blue sky science with no practical applications. We have to write grant applications and compete with other universities for this funding. Governments also fund the equipment that we use, such as the Hubble telescope and the observatories in places such as Chile, Hawaii and the Canary Islands. We compete with other universities for the time on these telescopes.

It’s mostly taxpayer money, for which I’m very grateful that people realise that learning where we live and what the universe is like is important enough to spend reasonably large amounts on.

Faradays disc electric generator of 1831. Blue sky research of its day.

NSB : Does the technology that is developed for astronomy result in any spin-offs that do have commercial applications

Alfonso : Certainly, everybody now carries a phone in their pockets that has got a camera which uses a detector called a CCD - those detectors were developed partly for astronomy. In the 80s those detectors were very small, very expensive and one detector would cost hundreds of thousands of pounds. Now they cost only a few pounds, you carry them in your pocket and you don’t think about them. And space technology, communications technology, data processing technology - it all relates to sciences like astronomy.

A 2.1MP CCD from a digital camera. 2.1MP? That’s so yesterday. . .. 

NSB : The universe is a very big place, could you give some idea of just how big it is?

Alfonso : Probably the best thing to do is to start with something that we know about, such as the Moon. We can talk about distances by thinking about the fastest thing we know about - light, which travels at 300,000km/sec. It takes about 1 second for the light from the Moon to reach us and about 8 minutes for light to reach us from the Sun.

Moving to the scale of the solar system, it takes light about 8hrs to get from the Sun to the furthest planet, Neptune, and a few light months to reach the farthest reaches of the solar system where comets are in the Oort cloud.

Now, if we wish to get to the nearest star, that is 4 light years away.

The next big thing out there is our own Milky Way, our own galaxy that contains hundreds of billions of stars. This is perhaps a hundred thousand light years in size.

But we haven’t really started yet because there are about 100 billion galaxies in the universe. If we go to our nearest galaxy, the Magellanic Clouds, which we can only see from the Southern Hemisphere, these are 200,000 light years away and the nearest galaxy which is comparable to our own is the Andromeda galaxy which is about 2.5 million light years away.

And if we go the most distant galaxies that we can observe we starting getting to about 10 billion light years.

And the furthest we can see is the distance that light has travelled since the beginning of the Universe and that is about 13-14 billion light years.

The Universe.IS.VERY.BIG 

NSB: One thing I hadn’t realised is that the Magellanic Clouds were so close, that’s almost touching distance really !

Alfonso : In many ways they are, in fact touching. There is something called the Magellanic Stream which is material that is pulled from the Magellanic Cloud by our own galaxy and eventually, the Magellanic cloud will merge with our own galaxy.

NSB : When you take these pictures of very distant galaxies, why isn’t there something in the way? How do you get these clear lines of sight to such distant objects?

Alfonso: That is a very good question! The first thing you have to realise is that space is mostly empty and it is true that there is gas and dust in the way and in some directions there is more than in others. If we look towards the centre of our own galaxy we find it very hard to see because there is lots of gas and dust, which for astronomers means particles that are like soot. But if we look away from the plane of our own galaxy then the amount of dust that we see is very small and because space is largely empty, light can travel unimpeded from pretty much the beginning of the universe.

Different types of light travel better than others. We know that visible light travels through dust much worse than longer wavelengths such as infra-red and radio can get through pretty much anything

NSB : Could you tell us a little about the Lockman Hole, which may be related to this issue.

Alfonso : The Lockman hole is a direction away from the plane of our galaxy where the amount of gas is quite small. It is a very transparent window, as it were. It was discovered first when people were looking in X-rays, which have got quite a lot of difficulty travelling through dust and gas and they found a region [of the sky] where the amount of dust was quite small and they could point their X-ray telescopes and see lots of galaxies. Because there had been quite a lot of studies of galaxies in this direction, initiated by X-ray telescopes, other telescopes followed the same direction. In fact, the famous image of many distant galaxies was taken in the Infra-red. They could have done this study in any direction, but they pointed towards the Lockman Hole because of the information that was already available about the galaxies there.

Herschel Space Telescope image of the Lockman Hole.
Many of the points of light are galaxies, each with  hundreds of billions of stars.
Bonkers, isn’t it?

NSB : When you are looking at a star or a galaxy, how do you know how far away it is.

Alfonso : This is the most difficult thing in astronomy. We can measure the distance to the Moon and to the nearest stars using a technique called parallax where you look at the object from two different locations. So if I looked at the Moon from Britain and from Australia I would see that the apparent position of the moon is slightly different. The easiest way to demonstrate this is to hold a finger out in front of you and look at it with one eye covered and then with the other eye covered - the finger seems to jump from one place to another. That jump or change in position depends on how far away it is and you can do some very simple trigonometry to calculate the distance to the object.
To the nearest stars we observe them in June, say, and then in December. And in that time the nearest stars appear to change their position by a tiny amount, perhaps a 60th of a 60th of a degree. We can only do this for a relatively small number of nearby stars and we can do it better and better from space, we have telescopes out there like the Gaia mission which will be measuring the distance to billions of stars using exactly this technique.

NSB :So up to what distance, how many light years, can this technique work to?

Alfonso : Well, if you do it from the ground you can only maybe a 100 light years away, give or take. But from space, using very sophisticated measurements where you look at things time and time again and measuring the positions very accurately, you can make the technique for a fair fraction of the galaxy, thousands of light years. And this is very recent, we have only been able to do this from space for maybe the last 10-15years.

So that covers quite a lot of the stars in our galaxy - but it doesn’t get us anywhere near the end of the universe and this is where is gets harder and more uncertain.

When you measure the distances to certain stars using parallax you find the some of them, such as Cephids, change their brightness in a very peculiar way that we can recognise and is related to how bright they are. And if you know how bright something really is and how bright it looks, you can work out how far away it is. This is because moving something twice as far away, make it four times dimmer. People have been able to see Cephids all the way to other galaxies.

A particularly useful object is a type of supernova which, for reasons we don’t completely understand, is always of approximately the same brightness. They are extremely bright, which means we can see them very far away, up to half way to the edge of the universe. Again, as we know how bright they are, and we can see how bright they appear, we can then work out how far away they are. These supernovas have been used to measure how large the universe is and how fast it is expanding. We call these kinds of objects “standard candles” which means they always shine with approximately the same brightness.

(NB: An interesting article on techniques to measure astronomical distances can be found here)

Tycho's Nova, the remnant of a Type Ia supernova - an (admittedly very large) standard candle

NSB: Galaxies are often spinning structures. Why is this? Why aren’t they just big balls of stars?

Alfonso : Well some galaxies are just big balls of stars, these are galaxies called elliptical galaxies which can be round, rugby ball shaped or more elongated.

But a large number of galaxies look like they are spinning, they are spiral galaxies. And we can show they are spinning by using Doppler effect to measure the speed of the spiral arms that are moving towards us compared to the arms that are moving away from us.

We have an approximate answer to why they rotate but galaxy formation is still an evolving science. What you have to realise is that if something very large is rotating very slowly and then becomes smaller it will spin faster. This is well known law of physics called the conservation of angular momentum, which sounds very complicated but is like when an ice skater who is spinning slowly with their arms outstretched pulls their arms in and spins much faster. When galaxies form out of large clouds of gas, even if there is only a small rotation at the start, it will increase as the galaxy collapses.

So now the questions is why is there some rotation at the beginning. Galaxies do not form in isolation, they interact with other galaxies and gas clouds that are nearby, some may be moving past, some may fall into each other, perhaps at an angle, and merge. A galaxy could orbit a cloud of gas and, through the effect of gravity, cause a small amount of spin in the gas cloud. And these small rotations increases as the gas cloud then collapses.

NSB : Moving on to your area of research, how do the galaxies in the very early universe compare to those we see today.

Alfonso : The galaxies in the very early universe are younger in several ways, they have more dust and gas - and this is the raw material to form stars. And we do see them forming more stars, much faster, than nearby galaxies. They tend to be more irregular they haven’t had time to form regular shapes.

NSB : Just thinking of any youngsters out there who are considering studying physics - do you have any tips that you have found useful in your studies that you can pass on?

Alfonso: The first thing is that you must like it. Physics is not a subject you can study thinking that “ok I am going to get a good job at the end of it” because if you do not really like it you will struggle and you will not do well. The raw materials you need would be to be able to do maths reasonably well. When you study physics you will find that it is full of equations, it’s impossible to remember all those formulae. What you need to do is to think about the concepts and figure things out. Get the basics right. I can’t remember most of the formulae that I use in my work, but I can derive them if I understand the principles. So you need an analytical mind, not be scared of maths and to try to derive things logically instead of memorising everything.

NSB : Can you give a little bit of a flavour for the kind of careers that the students on your course end up in?

Alfonso : There is quite a range. We are very fortunate that physics is a subject that leads to many careers. Some of them become physicists and researchers, both in an academic environment and in technology companies. Some go into financial modelling or engineering. They are very numerate so they find careers in finance, computing, maths.The main thing a physicist learns is to solve problems to which you don’t know the answer. That is the key issue.

Physicists could end up at CERN working on this baby here, the ATLAS detector at the LHC. . .

. . . or they could end up at the Gherkin. .  .

NSB : It’s perhaps worth mentioning that many of the advances in computer technology, such as chip design, have been driven by a better understanding of the physics of how these materials operate.

Alfonso : Certainly, and here in Nottingham the department has a very strong tradition in solid state physics and semiconductor physics, developing new semiconductor techniques. For instance, if you come to the physics building there is a company called E2V who develop electronics like the CCD’s that we talked about earlier. They share our building and we collaborate with them.

NSB: The show talked to chemist Deborah Kays recently, who has a great love for the element Boron, she just likes that element, and I wondered whether there were any stellar objects that you had a particular fondness for.

Alfonso : There is a class of objects called galaxy clusters that I like because I can see the interactions between them, sometimes they collide and sometimes the properties of the galaxies change because they are living in these clusters.

Also, a particular type of galaxy called a lenticular galaxies, which are galaxies that are transforming from forming lots of stars to not forming many stars. The process that switches off that star formation fascinates me. I have put quite a bit of effort, and that of my PhD students to answer that question and we have made quite good progress.

NSB : Can you give some information on how ordinary members of the public can get involved and find out more about the research that is going on at the University.

Alfonso : Well, we have an active series of public lectures to which everybody is welcome. People can visit our website to find out what is happening at the department. The University also has open days twice a year where people are welcome to visit, either because they are interested in studying physics or because their children may be.

We also have a large outreach programme in which, for example, there is an inflatable planetarium that we take to schools. So it any listeners are thinking that they would like this to visit their school the please get in touch! We would be delighted, it is part of our job, we want to bring physics and astronomy to people because one day they may become scientists.

(NB: You can read a report on a public lecture that Alfonso presented here)

NSB : The last question we have, which we ask all our guests, is something that I am always keen to hear the answer to : What do you think is the best thing about living in the UK ?

Alfonso : I have been in the UK since 1988 and there are two things that I have found very welcoming and, for me, very important about this country.

One is the very strong sense of fair-play. People value it and if something is not fair, people rebel against it immediately.

And the other thing, on a much lighter note is that people value a sense of humour. A good sense of humour is something that I really like. I’m not saying something that my countrymen don’t know in Spain when I say that the British sense of humour is much better than the Spanish sense of humour because in the UK we laugh at ourselves, that is something that I always find very curious. If you look in the personal ads in a newspaper, one of the things that people look for is a good sense of humour and that is a very important quality because life is tough enough so let us laugh every now and then and we will all be a little happier.


Image Credits: Notts Uni Main Building, Notts Uni Int House, Faraday Disk, CCD, Tycho, ATLAS, London