Physics

Physics

When you look back, most people would have thought we were absolutely crazy to do this. We just refused to accept that it wasn’t going to happen.

Andrew Wilson, a physicist at the University of Otago, explains the determination of his team, which became the first in the Southern Hemisphere to create a Bose-Einstein Condensate, Otago Magazine, Issue 13, February 2006

Dan Walls (1942-1999), a theoretician who pioneered the field of quantum optics, has been described as the greatest New Zealand physicist since Ernest Rutherford.

Born in Napier, Walls studied physics and mathematics at the University of Auckland and later, as a Fulbright scholar, at Harvard University under Professor Roy Glauber, who became a life-long friend. Walls returned to New Zealand and established the school of theoretical physics at the University of Waikato and the quantum optics group at his alma mater.

His research interest centred on interactions between light and atoms. In particular, he was fascinated by ways that the particle-like nature of light (photons) could be controlled to make optical systems less susceptible to unwanted fluctuations. When a single atom absorbs and re-emits light, the photons come out in a regular steady stream – unlike the random clumps that are emitted by lasers or light bulbs – and Walls developed a quantum description of light to account for this effect.

Walls’ contribution was recognised through many awards, including the Paul Dirac Medal for theoretical physics in 1995, which put him in the company of previous recipients such as Stephen Hawking and Roger Penrose. His research has applications for quantum computing and the creation of new states of matter.

Coldest spot in universe

Andrew Wilson, a physicist at the University of Otago, won’t easily forget August 1998. A note on his fridge said ‘get Bose-Einstein Condensate and have a family’ and he achieved both goals, if not in the order he had planned.

His research team soon became the first in the Southern Hemisphere to produce the elusive new state of matter, which had been predicted by Albert Einstein and a young Indian physicist called Satyendra Bose. To create the condensate, atoms need to be supercooled to within a billionth of a degree above absolute zero, which is colder than anywhere else in the universe. When the condensate forms, the atoms take on quantum properties and form matter waves. Making the condensate takes more than a minute, but the elusive state exists for only 20 seconds – still enough time to run experiments to confirm the theory and to investigate its properties.

No resistance

Back in 1988, Jeff Tallon and his colleagues discovered that an oxide of bismuth and copper performs well as a high-temperature superconductor (HTS), which conducts electricity without resistance when cooled below a threshold temperature. Tallon’s team at Industrial Research fought for 16 years to obtain a US patent, which was finally issued in 2004. This is currently the only HTS material applied in long-length wires and is now being used to manufacture very efficient and compact cables, transformers, magnets, generators and motors.

Stardust

Clifton Ellyett and Colin Keay began investigating meteors in Canterbury during the 1950s. Since then, Jack Baggaley, a physicist at the University of Canterbury, has developed their work into one of the world’s leading meteor research programmes. Using the Advanced Meteor Orbit Radar, or AMOR, at Birdlings Flat, to measure the trajectories of dust particles entering the atmosphere at high speed, Baggaley has traced the geometry of these interplanetary dust clouds and identified a stream of particles from outside the solar system.

Elementary particles

Cosmic rays are high-energy charged particles from outer space that travel at nearly the speed of light and strike the Earth from all directions. Thousands pass through our bodies every second.

One of the first New Zealanders to be involved in cosmic ray research was William Pickering (1910-2004), who conducted balloon-borne experiments before joining the Jet Propulsion Laboratory (JPL) and pioneering telemetry systems for rockets. Director of JPL from 1954 to 1974, Pickering was responsible for the first US satellite Explorer 1, the Ranger and Surveyor missions which mapped the moon in preparation for Apollo, and missions to all major planets.

Sir Ian Axford, former director of the Max Planck Institut für Aeronomie (MPAE), has conducted research into the origin and acceleration of cosmic rays, and the properties of plasmas in astrophysics. He pioneered research into the dynamics of Earth’s magnetosphere and its interaction with solar wind.

When high-energy cosmic rays undergo collisions with atoms of the upper atmosphere, they produce a cascade of secondary particles that shower down through the atmosphere to the Earth’s surface. In the 1950s, Jack Storey installed a cosmic ray shower detector at the University of Auckland to determine whether the galactic centre was a cosmic ray source. During the 1970s, Philip Yock, also at the University of Auckland, searched for free quarks in cosmic radiation.

Particle astrophysicist Jenni Adams leads the University of Canterbury team participating in the Radio Ice Cerenkov Experiment (RICE) and IceCube projects, which aim to detect ultra-high-energy neutrinos from space through their interactions with the Antarctic ice cap.  

By Marilyn Head and Veronika Meduna

Medals and awards

Dan Walls: FRSNZ, FRS, Einstein Medal for laser science, Michaelis Memorial Medal, Hector Medal, Australian Optical Society Medal, Paul Dirac Medal

Ian Axford: FRS, FRSNZ, Rutherford Medal, Fleming Medal (AGU), Space Science Award (AIAA), Chapman Medal (RAS), Knight Bachelor

William Pickering: NASA’s Distinguished Service Medal, National Medal of Science, ONZM

Jack Baggaley: University of Canterbury Research Medal, Michaelis Memorial Medal, Geddes Memorial Prize, FRSNZ, FRAS

Clifton Ellyett: Murray Geddes Prize

Image courtesy of the University of Otago.

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