Discovering the Secrets of Absolute Zero: Scientists' Techniques Revealed

[KLscilevothma]

I was reading Discover (November 2003), on pg 18 Ask Discover, it says "Absolute zero cannot be reahed experimenally, but scientsts have cooled small samlples of atoms to just one ten-billionth of a degree above absolute zero."

How could scietists cool the sample to such a low temperature ?

 

[Ivan Seeking]

Originally posted by KL Kam
I was reading Discover (November 2003), on pg 18 Ask Discover, it says "Absolute zero cannot be reahed experimenally, but scientsts have cooled small samlples of atoms to just one ten-billionth of a degree above absolute zero."

How could scietists cool the sample to such a low temperature ?

Hey KL

LASER Cooling

Laser trapping and cooling does just that. Photons, the quanta of light, carry momentum. When an atom absorbs a photon, the photon's momentum gives the atom a kick in the direction the photon was traveling. The atom can only absorb a photon if the photon's energy matches the energy difference between two of the atom's energy levels. Careful tuning of the laser frequency insures that only atoms moving toward the light can absorb photons and be slowed.

http://www.physicscentral.com/action/action-00-4.html

The idea of using lasers to trap and cool molecules for study began over a lunchtable conversation at Bell Labs in Holmdel, N.J. more than 10 years ago. Today, because of his idea, former Bell Labs researcher Steven Chu is one Nobel Prize in Physics richer.

http://www.bell-labs.com/user/feature/archives/chu/

There was no magic involved — just physics — as Nobel Prize laureate William Phillips demonstrated the principles behind his laser cooling and trapping technique to a mystified crowd of students, professors and college alumni, and offered observers a taste of just how cold atoms cooled by the technique are

http://www.sccs.swarthmore.edu/org/phoenix/2001/2001-03-22/news/10875.html


A note on Chu; I saw him a few years ago at Stanford. He spoke for quite some time about the importance of encouraging imaginative thinking.

 

[KLscilevothma]

Thanks Ivan.

PS. I was in a hurry and didn't notice those spelling mistakes in the first post.