First, let's revisit the idea of condensation. Condensation occurs when a the particles of a gas are cooled and form a liquid. Several particles group together and form the denser liquid molecules. This is all due to the loss of heat the particles experience. They condense into a larger, denser substance. The same thing happens in the BEC, but at very extreme levels. At very low temperatures, there is no longer a transfer of heat like there is in solids are liquids. Thus, all particles are at the same energy level, and essentially form a giant "blob" of particles that all act the same way.
The BEC was first theorized by Satyendra Bose and Albert Einstein in the 1920's. For many years it remained just that: a theory. However, in 1995, scientists Eric Cornell and Carl Wieman, along with MIT physicist Wolfgang Ketterle, succeeded in creating a BEC in a laboratory setting.
They did this by cooling the particles of a gas to extremely low temperatures, first by using a laser, and then something called evaporative cooling.
The laser cools the particles by actually bouncing off of them, absorbing more heat than it puts in. As the photon of the laser hits the atoms, the electrons within the atoms of the gas absorb the photon, jump to a higher energy level, and spit the photon back out. This decreases the amount of heat/energy within the gas (this is similar to the idea of spectroscopy and energy levels learned in Chemistry 20). This process gets the particles to about 1/10,000th of a Kelvin above absolute zero.
Next comes the evaporative cooling. In order to keep the gas particles concentrated into a single area, they are placed within a special magnetic field that prevents them from escaping. If they were in a regular container, the particles would just stick to the walls. This magnetic field acts as a insulator that can trap heat as well. Heat from the gas particles is released, like the steam from a cup of coffee. It has to be released slowly, so that too many particles do not escape. When this is done, the gas has been cooled to less than one millionth of a degree (one microkelvin) above absolute zero.
Cornell and Wieman shared a 2001 Nobel Prize in Physics with Ketterle for their discovery. Experiments involving the BEC has led to further research into the behaviour of particles at extremely low temperatures.
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| Cornell and Wieman, the super cool guys who first created the Bose-Einstein Condensate. |
They did this by cooling the particles of a gas to extremely low temperatures, first by using a laser, and then something called evaporative cooling.
The laser cools the particles by actually bouncing off of them, absorbing more heat than it puts in. As the photon of the laser hits the atoms, the electrons within the atoms of the gas absorb the photon, jump to a higher energy level, and spit the photon back out. This decreases the amount of heat/energy within the gas (this is similar to the idea of spectroscopy and energy levels learned in Chemistry 20). This process gets the particles to about 1/10,000th of a Kelvin above absolute zero.
Next comes the evaporative cooling. In order to keep the gas particles concentrated into a single area, they are placed within a special magnetic field that prevents them from escaping. If they were in a regular container, the particles would just stick to the walls. This magnetic field acts as a insulator that can trap heat as well. Heat from the gas particles is released, like the steam from a cup of coffee. It has to be released slowly, so that too many particles do not escape. When this is done, the gas has been cooled to less than one millionth of a degree (one microkelvin) above absolute zero.
Cornell and Wieman shared a 2001 Nobel Prize in Physics with Ketterle for their discovery. Experiments involving the BEC has led to further research into the behaviour of particles at extremely low temperatures.
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