The Mudcat Café TM
Thread #59418 Message #2040694
Posted By: Amos
01-May-07 - 06:02 PM
Thread Name: BS: The Mother of all BS threads
Subject: RE: BS: The Mother of all BS threads
Hey Mom!! I discovered Rapaire's REAL problem -- he's one of them Efimov trimers, and physicists have been trying to track him down for years!! Good thing we figgered it out. This Deistic We business was gonna get him committed to a loony bin, but now he can go to a think-tank instead! YAAAY!!!
"THE EFIMOV EFFECT: THREE*S COMPANY, TWO'S A CROWD. At the April APS
meeting in Jacksonville, physicists discussed the recent observations of
the Efimov effect, a purely quantum phenomenon whereby two particles
such as neutral atoms which ordinarily do not interact strongly with one
another join together with a third atom under the right conditions. The
trio can then form an infinite number of configurations, or put another
way, an infinite number of "bound states" that hold the atoms together.
The effect was first predicted around 1970 by a physicist named Vitaly
Efimov, then a Ph.D. candidate at the time, but was originally
considered "too strange to be true," according to the University of
Colorado*s Chris Greene, in part because the atoms would abruptly
switch from being standoffish to becoming stuck-together Siamese
Triplets at remarkably long distances from one another (approximately
500-10,000 times the size of a hydrogen atom in the case of neutral
atoms). For decades, experimenters tried in vain to create these
three-particle systems (which came to be known as "Efimov trimers").
In 1999, Greene and his collaborators Brett Esry and Jim Burke
predicted that gases of ultracold atoms might provide the right
conditions for creating the three-particle state. In 2005, a research
team led by Rudi Grimm of the University of Innsbruck in Austria finally
confirmed the Efimov state in an ultracold gas of cesium cooled to just
How do the neutral atoms attract one another in the first place? At
small distances, ordinary chemical bonding mechanisms apply, but at the
vast distances relevant to the Efimov effect, it is mainly through the
van der Waals effect, in which rearrangements of electrical charge in
one atom (forming an "electric dipole") create electric fields that can
induce dipoles in, and thereby attract, neighboring atoms. The
observation of the Efimov effect is a coup for being able to study the
rich quantum physics between three particles.
The effect can conceivably occur in nucleons or molecules (and any
object governed by quantum mechanics). However, it will likely be
harder to observe in those systems because physicists cannot alter the
strengths of interactions between the constituent particles as easily as
they can in ultracold atom gases (through their "Feshbach resonances").
But the effect could provide insights on such systems as the triton, a
nucleon with one proton and two neutrons, in addition to the BCS-BEC
crossover, in which atoms switch from forming weakly bound Cooper pairs
to entering a single collective quantum state.
(See also article by Charles Day, Physics Today, April 2006, Esry et al, Phys. Rev. Lett, 30
August 1999, and Kraemer et al., Nature, 16 March 2006)."