AUSTRALIAN FRONTIERS OF SCIENCE, 2008

The Shine Dome, Canberra, 21-22 February

Session 3: Accelerated nuclei – probing quantum and geological landscapes
Chair: Professor David Jamieson

David Jamieson completed his PhD in physics at the University of Melbourne in 1985 and then spent 4 years as a postdoctoral research fellow at Caltech (USA) and the University of Oxford (UK). He is a Professor of Physics at the University of Melbourne and the director of the Victorian node of the Australian Research Council Centre of Excellence for Quantum Computer Technology. This centre is working on new ways of storing and processing information using the strange laws of quantum mechanics. David and his team use ion beam physics to build devices containing single atoms. He has been a finalist in the Australian Awards for University Teaching. In the Einstein International Year of Physics 2005 he became President of the Australian Institute of Physics, a role he filled until the end of 2006.

Let me say a few words of introduction about accelerated nuclei. This year, 2008, is the 99th anniversary of Ernest Rutherford's discovery of the nucleus, by the use of a beam of fast charged particles accelerated nuclei produced from a natural radioactive decay, which allowed him to probe the inside of atoms. And, to everyone's surprise, there was a nucleus in there. This triggered an enormous explosion of activity in the field of nuclear physics, and the benefits of artificially accelerated nuclei soon became clear. The first particle accelerator, for accelerating ions and nuclei to high speeds, was built in Cambridge in 1932, and went on to uncover a whole lot of properties of the nucleus as the foundation of our knowledge today.

Australia was watching. Only a few years later, in 1938, Australia's first particle accelerator switched on, in my laboratory in Melbourne. It went on to do a lot of pioneering nuclear physics measurements, along with others that switched on around the world, and pretty soon the first discovery and, in my view, still one of the most significant discoveries was made, namely, the process of thermonuclear fusion. We have to remember that as recently as 1950 people still didn't know really where the sun got its energy from, and I think that is a remarkable result.

But now in Australia there are three laboratories with particle accelerators my own lab in Melbourne, where the accelerator is used for single-atom quantum electronics; at ANSTO, the Australian Nuclear Science and Technology Organisation, where the accelerators are mainly used for materials characterisation, mass spectrometry; and at the Australian National University, where beams of charged particles are used for materials science, nuclear physics and accelerator mass spectrometry.

Dr Nanda Dasgupta's talk today is very interesting because it is at the interface of two great disciplines of physics. The first great theory is quantum mechanics. I would like to tell you what Richard Feynman had to say on the topic. (Richard Feynman was the late great theoretical physicist and Nobel Laureate and bongo player.) He said, 'I think I can safely say that nobody understands quantum mechanics.'

Quantum mechanics has many strange concepts, with no classical interpretation. One is that a quantum particle can be in two places at the same time. A second is that two quantum particles, although widely separated, can share common attributes, and when measured will display the same or complementary attributes, even though they don't have those attributes until you measure them and they don't communicate with each other after the measurement. Don't try and understand any of this remember Feynman's words. But this theory is one of the most successful theories we have.

The other great theory is that of the nuclear forces. In fact, in nature there are four distinct forces, with quite different attributes. The most powerful and complicated of these forces arises from the leakage of the colour force from the quarks and the gluons in the constituents of the nucleus. We call this the 'strong force'.

And by way of introduction to Dr Toshi Fujioka's talk, I would just like to put it to you that one of the most profound questions we can ask about anything is: how old is it? It is not a problem for a newspaper or a person, but what about the silent rocks of our planet, or the mute remains of extinct branches of the human family tree? Well, all around us even in this room there are stray exotic atoms hidden amongst the overwhelming numbers of common, plain vanilla, ordinary atoms. These exotic atoms can come from the interaction of our planet with the interstellar environment. They have interesting tales to tell, if only we could sieve them out from the uncountable number of neighbours.

His talk is directed at finding answers to those seemingly intractable questions.