A Nobel physics prize winner, who lectures here this week, tells Science Editor Dick Ahlstrom about his work and a wholly new state of matter
Ask any pupil doing science and they will tell you there are three states of matter - solid, liquid and gas. Ask an older student and they might add a fourth, the superheated state known as a plasma. We now have to get used to a fifth state, supercooled matter so cold that it almost stands still.
This new state, known by the unwieldy name Bose-Einstein Condensate, has got physicists around the world in a flutter. By chilling clouds of atoms close to the coldest temperature possible, Absolute Zero, they take on remarkable new properties.
Instead of bouncing off one another they begin moving together in unison. They become "coherent" in the same way that the beam produced by a laser is coherent light. The discovery has allowed researchers to develop something called an atom laser, which promises remarkable new discoveries.
So impressive was the successful creation of a Bose-Einstein Condensate (BEC) that the two teams that first produced them were fast-tracked for a Nobel Prize in physics. The 2001 prize was given jointly to three researchers from the Massachusetts Institute of Technology, the US National Institute of Standards and Technology (NIST) in Boulder, Colorado, and the University of Colorado at Boulder.
One of these, MIT's Prof Wolfgang Ketterle, 43, has come to Ireland this week to give three public lectures and describe his excitement at the discovery.
Normally the prize is given many years after the original research was done, once the significance and true impact of the research has emerged, Prof Ketterle explains. It also often comes after scientific activity and interest has moved on to other subjects. The two teams created their condensates as recently as 1995 but such was the remarkable nature of the findings that the Nobel Prize came six years later.
The award was "just amazing and thrilling" Prof Ketterle says. "It filled the \ research community with joy. They were proud that the field was recognised while it is still active."
Prof Ketterle delivers a lecture on BEC this evening at the University of Limerick. He repeats this on Wednesday at Queen's University Belfast and on Thursday at Dublin City University. The object, he says, is "to try to convey the excitement about this new state of matter".
The temperatures needed to make a BEC are so low as to be almost unimaginable, hovering just a millionth of a degree above Absolute Zero, minus 273.15 Celsius. This is a million times colder than the coldest place known in the universe.
At Absolute Zero atoms are assumed to stop moving, but at this tiny step just above it the atoms lose their individual identity and begin to move together. "The atoms march in lockstep and move in a highly directional way," Prof Ketterle explains.
At warmer temperatures atoms in a gas flit about and bounce off each other in a chaotic way, but in a BEC they move about like soldiers on parade in a unified manner. When a condensate is achieved it "displays unique properties similar to a new form of matter", he says.
The teams in Colorado and Massachusetts were locked in a serious competition to be the first to achieve a BEC, Prof Ketterle says.
There was quite a bit of information traded in the run-up to the achievement, with one group presenting its latest findings at a conference and the other using this information added to new discoveries to make the next presentation.
The Colorado group, led by Dr Eric A. Cornell (39), of NIST and Prof Carl E. Wieman (50), of the University of Boulder got there first in June 1995 and Prof Ketterle's group produced a BEC later that year in September. The three shared the prize last autumn because of their discoveries in BEC research and for their early studies of the properties of this new form of matter.
Further details from Dr John Costello at jtc@physics.dcu.ie