The end of a 71-year search was celebrated this month. On Oct. 9, three U.S.-based scientists shared the 2001 Nobel Prize in physics for creating a new state of matter.
The award went to Americans Eric A. Cornell, 39, of the National Institute of Standards and Technology in Boulder, Colorado, and Carl E. Wieman, 50, of the University of Colorado, along with German scientist Wolfgang Ketterle, 43, of the Massachusetts Institute of Technology. Their creation of a Bose-Einstein condensate was first theorized by Albert Einstein in 1924, based on the calculations of Indian physicist Satyendranath Bose.
Dr. David Kagan, chair of the physics department at Chico State University, explained that the Bose-Einstein condensate was achieved by cooling 2,000 rubidium atoms to a few billionths of a degree above absolute zero, which is minus 459.67 degrees Fahrenheit or minus 273.15 Celsius.
"When this is done, they start to act not as individual particles, but as a single entity," Kagan said.
One way to describe the Bose-Einstein condensate is that the condensate is to ordinary matter as laser light is to the light from a light bulb.
"The waves of light that come off a light bulb aren't in sync with each other," Kagan said. "The waves spread out uniformly, as opposed to waves of light from a laser which are in sync."
In this same way, the Bose-Einstein condensate atoms bond together to create something like an atomic laser, Kagan said.
The Royal Swedish Academy of Sciences, the organization that awards the Nobel Prize, speculated that this discovery could bring about revolutionary applications in fields such as precision measurement and nanotechnology. This means more accurate clocks, perfect circuits or even quantum computers. However, because the unique state of Bose-Einstein condensates can only last for a few minutes, the current practical applications are limited.
"One of the things that could give you a hint about applications is who's funding the research," Kagan said. "If it's for the department of defense, I imagine it would have something to do with communications technology."
As most people learned in high school science classes, atoms are the smallest particles of matter that can undergo chemical reactions and retain their identity. Because atoms are fifty million times smaller than the dot over the letter "i," they are difficult to study directly. However, the Bose-Einstein condensate "atomic laser" is 20 microns across, which is about one-fifth the thickness of this paper.
"It's easier to tweak it and see what happens - to manipulate it and to get data out of it," Kagan said.
Discovery of the Bose-Einstein condensate is important because it helps answer the question how and why the universe exists as it does.
"The universe is composed of two distinct classes of particles and they behave very differently," he said.
Fermions include protons, neutrons and electrons, which are the three constituents of atoms, while bosons include light photons and alpha-particles, the unique state of matter in liquid helium. Kagan explained that if six fermions were cooled to near absolute zero, they would arrange themselves into separate energy levels, with some stronger and some weaker.
"Bosons don't have that property," he said. "If you have six bosons and you cool them off, they will all go to the lowest energy level. We don't understand, fundamentally, why fermions act differently than bosons."
In every atom, the negatively charged electrons orbit the positively charged nucleus. This keeps nuclei away from each other and gives matter the form that we experience.
"Why don't the electrons simply fall into the nucleus and neutralize?" Kagan asked. "It's Bose-Einstein because the electrons are fermions and they don't all go into the same energy state. So the fact that atoms exist at all is traceable to the issue of fermions and bosons."
Kagan said that since humans owe their existence to the existence of atoms, this is a fortunate state of affairs.
"That turns right back into how the universe was born and how the universe is going to end," he said. "It can't just collapse into nothingness because of these fermiotic properties. So how did these particles come into existence? Why do they behave the way they do? Why isn't everything a boson?"
The answers to these questions can now be explored using the Bose-Einstein condensate, Kagan said.
While the search to verify the Bose-Einstein condensate may have been completed this month, the journey of science is only just beginning.
"Science is a continual search," he said. "It's never over. There is no Holy Grail of science. Every time we understand one thing there are a hundred more questions it brings about. (There is) job security for scientists."
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