Monday, March 29, 2010
... "borrowed" from the pages of Wikipedia:
The Bose-Einstein Condensate is a state of matter of a dilute gas of weakly interacting bosons confined in an external potential and cooled to temperatures very near to absolute zero (0 K or −273.15 °C). Under such conditions, a large fraction of the bosons occupy the lowest quantum state of the external potential, at which point quantum effects become apparent on a macroscopic scale.
This state of matter was first predicted by Satyendra Nath Bose and Albert Einstein in 1924–25. Bose first sent a paper to Einstein on the quantum statistics of light quanta (now called photons). Einstein was impressed, translated the paper himself from English to German and submitted it for Bose to the Zeitschrift für Physik which published it. Einstein then extended Bose's ideas to material particles (or matter) in two other papers.
Seventy years later, the first gaseous condensate was produced by Eric Cornell and Carl Wieman in 1995 at the University of Colorado at Boulder NIST-JILA lab, using a gas of rubidium atoms cooled to 170 nanokelvin (nK). For their achievements Cornell, Wieman, and Wolfgang Ketterle at MIT received the 2001 Nobel Prize in Physics.
This phenomenon was predicted in 1925 by generalizing Satyendra Nath Bose's work on the statistical mechanics of (massless) photons to (massive) atoms. (The Einstein manuscript, once believed to be lost, was found in a library at Leiden University in 2005. The result of the efforts of Bose and Einstein is the concept of a Bose gas, governed by Bose–Einstein statistics, which describes the statistical distribution of identical particles with integer spin, now known as bosons. Bosonic particles, which include the photon as well as atoms such as helium-4, are allowed to share quantum states with each other. Einstein demonstrated that cooling bosonic atoms to a very low temperature would cause them to fall (or "condense") into the lowest accessible quantum state, resulting in a new form of matter.
Further experimentation by the JILA team in 2000 uncovered a hitherto unknown property of Bose–Einstein condensates. Cornell, Wieman, and their coworkers originally used rubidium-87, an isotope whose atoms naturally repel each other, making a more stable condensate. The JILA team instrumentation now had better control over the condensate so experimentation was made on naturally attracting atoms of another rubidium isotope, rubidium-85 (having negative atom-atom scattering length). Through a process called Feshbach resonance involving a sweep of the magnetic field causing spin flip collisions, the JILA researchers lowered the characteristic, discrete energies at which the rubidium atoms bond into molecules, making their Rb-85 atoms repulsive and creating a stable condensate. The reversible flip from attraction to repulsion stems from quantum interference among condensate atoms which behave as waves.
When the scientists raised the magnetic field strength still further, the condensate suddenly reverted back to attraction, imploded and shrank beyond detection, and then exploded, blowing off about two-thirds of its 10,000 or so atoms. About half of the atoms in the condensate seemed to have disappeared from the experiment altogether, not being seen either in the cold remnant or the expanding gas cloud. Carl Wieman explained that under current atomic theory this characteristic of Bose–Einstein condensate could not be explained because the energy state of an atom near absolute zero should not be enough to cause an implosion; however, subsequent mean field theories have been proposed to explain it.
Because supernova explosions are also preceded by an implosion, the explosion of a collapsing Bose–Einstein condensate was named "bosenova", a pun on the musical style bossa nova.
The atoms that seem to have disappeared almost certainly still exist in some form, just not in a form that could be accounted for in that experiment. Most likely they formed molecules consisting of two bonded rubidium atoms. The energy gained by making this transition imparts a velocity sufficient for them to leave the trap without being detected.
Long story short, don't sleep on the new state of matter!
Monday, March 22, 2010
I collect records, and have been doing so since I was a kid. Some of the first things I picked up were "Houses of The Holy" by Led Zeppelin, and "Let It Be" by the Beatles. At some point in the early 2000's I had seen a painted record by the local Graff Legend RockOne, and I loved it, around this same time I stole a Sotheby's catalog with a Gerhard Richter painting, it was one of his abstractions on a record.... I saw fit to attempt to combine these two Ideas together: Graffiti meets fine art on vinyl.
Friday, March 19, 2010
The vehicle you see smashed up hit a van, this said van hit the work truck, and I was in a car accident... Nothing too serious, but these kinds of things tend to "stir up the molecules." We had been attempting to put up signs at one location, and the posts these things were supposed to go on were pulled out of the ground. We had put them in the back of the truck to take back to the shop. It was a good thing they had been tied down, that coupled with the fact that the van tried to swerve to avoid hitting us and smashed up the side with out the metal posts, which easily could have hurt someone had they gone through the windshield... The ended up catching the kids who stole/wrecked the car. I suppose this was just another reminder that people get into accidents every day, and life can be shorter than we plan it to be. I'm glad it was the truck that got screwed up and not us.
Thursday, March 18, 2010
Both of these things are real, I don't make this stuff up.... I wanted this to be some kind of reflection of my travels, but I usually just ride the bus to work, or around town. Hopefully this can be a showcase for the work I create, as well as a place to purge the inane junk collection in my brain.... enjoy!