For the discussion, here are two signficiant zero point energy related articles:
THE CASIMIR FORCE, a 1948 theoretical prediction in which the seemingly desolate "vacuum" creates a tiny force between a pair of conductors, has been precisely measured for the first time. According to quantum mechanics, empty space (the "vacuum") is not truly empty but instead contains fleeting electromagnetic waves and particles that pop into and out of existence. However, when the vacuum is bounded by a pair of conducting surfaces, the only electromagnetic waves that can exist are those with wavelengths shorter than the distance between the surfaces. The exclusion of the longer wavelengths results in a tiny force between the conductors. To measure the Casimir force, Steve Lamoreaux, now at Los Alamos (505-667-5005), employs a torsion pendulum, a twisting horizontal bar suspended by a tungsten wire. The attraction between a gold-plated sphere and a second gold plate causes a small twisting force in the bar. By applying a voltage sufficient to keep the twisting angle of the bar fixed, Lamoreaux determined the force caused by the attraction of the plates. His results agree with theory to a 5% level. (Upcoming paper in Physical Review Letters.) Researchers previously measured the Casimir-Polder force (Update 122), a different but related effect in which the vacuum creates an attraction between a conducting plate and a neutral atom.
ZERO-POINT MOTION IN A BOSE-EINSTEIN CONDENSATE has been quantitatively measured for the first time, allowing researchers, in effect, to study matter at a temperature of absolute zero. According to quantum mechanics, objects cooled to absolute zero do not freeze to a complete standstill; instead they jiggle around by some minimum amount. MIT researchers (Wolfgang Ketterle, 617-253-6815) measured such "zero-point motion" in a sodium BEC, a collection of gas atoms that are collectively in the lowest possible energy state (Update 233). According to Ketterle, "the condensate has no entropy and behaves like matter at absolute zero." The MIT physicists measured the motion (or lack thereof) by taking advantage of the fact that atoms absorb light at slightly lower (higher) frequencies if they are moving away from (towards) the light. To determine these Doppler shifts (100 billion times smaller than those of moving galaxies), the researchers used a technique known as Bragg scattering. In this technique, atoms absorb photons at one energy from a laser beam and are stimulated by a second laser to emit a photon at another energy which can be shifted upward or downward depending on the atoms' motion towards or away from the lasers. Measuring the range in energies of the emitted photons allowed the researchers to determine the range of momentum values in the condensate. Multiplying this measured momentum spread (delta p) by the size of the condensate (delta x) gave an answer of approximately h-bar (Planck's constant divided by 2 pi)--the minimum value allowed by Heisenberg's uncertainty relation and quantum physics. While earlier BECs surely harvested this zero-point motion, previous measurements of BEC momentum spreads were done with exploding condensates having energies hundreds of times larger than the zero-point energy. (J. Stenger et al., Physical Review Letters, 7 June 1999.)