Cosmic Ray Research. This was what I did for my PhD in Tasmania. I was extremely fortunate in that the University of Tasmania is one of the leading laboratories in the world in the study of these sub-atomic strangers that wander into the solar system from outer space. I built lots of equipment I installed some of it in New Guinea, some went to Antarctica and I had my own cosmic ray laboratory half way up Mt. Wellington.
Building Satellites. My research in Tasmania led to an invitation to work at the Massachusetts Institute of Technology in the USA. The USA was preparing to send satellites to the orbits of Venus and Mars, and I suggested that an instrument be included on those spacecraft to measure the properties of the cosmic radiation. NASA agreed, and asked me and my colleagues to build the instruments. This we did, and they were flown on seven different satellites. We gained an immense amount of knowledge about the sun, and the magnetic fields in the solar system. I also learned not to be frightened of something that I had never done before. For a while I considered applying to be a scientific astronaut but I had two problems. The first you had to be an American. Secondly and a much greater difficulty you had to be less than 6 feet tall (183 cm). I am 186cm tall. I simply would not fit into the spacecraft. Pity!
A pioneer in a new form of astronomy. Astronomers have a poor record in recognising new forms of astronomy. First they argued that stars could not produce radio waves until Australian and British physicists and engineers showed otherwise. Then the astronomers argued that stars could not produce x-rays, until my boss at MIT a physicist proved them wrong. Within months I was using high flying balloons and later rockets to locate the x-ray stars in the galaxy. Sometimes it is very important that you do not believe what the experts tell you.
Exploring for buried minerals. Returning to Australia, I decided to look for another challenge. Mineral explorers use a form of physics called geophysics to locate minerals buried deep below the surface of the earth. CSIRO asked me to look at the geophysics being used in Australia and I was shocked as a physicist I could see that the techniques were hopelessly wrong for our environment. The techniques worked very well in Canada where the soil layer is thin. The situation in many parts of mainland Australia is very different the mineral layers can be 100 or more meters below the surface. We physicists designed new ways to see to that depth using electric and magnetic fields. Traditional geophysicists thought we were mad until our techniques were seen to work very well. That changed their minds very quickly. Our "crazy ideas" soon became the conventional way of doing things. Once again a win for the physicists way of looking at things.
Eyes in the sky. Changing your interests can be very useful to your career. Thus in my minerals work I frequently used ideas and instruments that I had learned about in space research. It gave me a real competitive advantage. So when the US said they were going to launch a satellite to photograph the earth from a height of 800 km the space physicist in me could see its implications. The Americans called it "remote sensing". Many of the practical people of Australia, the geologists, oceanographers, and the foresters for example called it "remote nonsense". They do not say that anymore everyday they use the techniques my colleagues and I developed, and they forget that it is only 15 years ago that they said we were mad and much ruder things. Incidentally, two of my young colleagues and I were awarded the Australia Prize a sort of Australian Nobel Prize for our work in remote sensing. So being a physicist, and seeing what all the experts cannot see, and being called mad, can bring its rewards.
My own scientific business. Leaving CSIRO I established my own business that provides scientific advice to governments and companies in Australia and overseas. My clients use me to peer into my crystal ball that is to use my physics to tell them how to do things faster, more accurately; or more safely. For this is the wonderful thing as we get better computers, electronics, and other technologies, so we can do useful things that were impossible just 5 years ago. It is my job to decide what new things are now possible and which ones we need to leave for a few more years yet.
And in my spare time? Firstly I live on, and operate a 850 acre farm. When I cannot solve a knotty problem of physics I talk about it to one of my bulls. It helps. I still indulge in aggressive bushwalking often with teenagers who make certain I do not dawdle. I do crazy things with my grandchildren. I am - I think - a pretty normal Australian physicists may be occasionally absent minded but they are not nerds.
So what do you need, to be a physicist? First I must tell you that I was not a particularly bright student at school or at the University. Others in my classes always seemed to understand things much better than I. I learned to ask dumb questions. I learned from my mistakes. It all added up. An important part of my education was through my passion for bushwalking in the Tasmanian southwest. I learned to trust my judgment, to persevere, and to survive.
Certainly mathematics is important. A willingness to ask "why does that happen" when you see something new. A keen interest in new discoveries regarding the world about us. Doing things in your spare time that are close to the technological limits for me it was experimenting with radio nowadays it might be doing strange things with a personal computer that even Bill Gates hasnt thought of. And reading widely (or using the world wide web) to learn about the physics that interests you.