Zero Point Energy, sometimes called Zero Point Fluctuations (ZPF) or even Quantum Vacuum Fluctuation Energy, with or without the optional quantum, is caused by the continual popping into existence of virtual particles. These particles vanish almost as soon as they've popped into existence.The particles, which arise as matter-antimatter twins, can interact but must, disappear within an interval set by Planck's constant. They are a result of random electromagnetic oscillations, they are whats left within a vacuum once you've extracted all the energy.
One way to explain this apparent contradiction is Heisenbergs Uncertainty Principle, this implies that it is impossible to have an absolutely zero energy condition. The same condition holds for light waves in space. For all wavelengths of light, there is a non-zero amount of that light. Adding up the energy for all those different wavelenghts, the amount of energy in a given space is enormous. Even though this is a difficult concept for traditional phyicists to come to terms with, the idea that all this vacuum energy exists is becoming more widley accepted, and the quantum physicists have come in from the cold.
So is there any evidence of all this free energy actually exists. Well there have been a number of experimental results that would suggest/show (depends on whether your a traditional physicist or not) that such energy actually exists:
The Casimir Effect - The most straight-forward evidence for vacuum energyVan der Waal Forces
The Lamb-Retherford Shift - Refers to a slight frequency alteration in the light emitted by an excited atom
Even for those of you who have read 'A Brief History of Time', by Prof. Stephen Hawkins - Hawkins Radiation, should it exist relies on the creation of virtual particles in matter/anti-matter pairs. One particle spirals into the Hole, the other escapes, causing the theoretical effect.
Imagine, for example, if you lived on a large plateau, so large that you didn’t know you were 1000 ft up. From your point of view, your ground is at zero height. As long as your not near the edge of your 1000 ft plateau, you won’t fall off, and you will never know that your zero is really 1000. It’s kind of the same way with this vacuum energy. It is essentially our zero reference point.
The energy of the vacuum is a puzzle in theories of quantum gravity since it should act gravitationally and produce a large cosmological constant that would cause space-time to curl up. The solution to the inconsistency is expected to be found in a theory of quantum gravity. There has been some interesting work, done in this field, by Haisch, Rueda, and Puthoff , where vacuum fluctuations are used to explain the effects of both gravity and inertia.
Puthoff believes that atoms themselves offer a way to extract this energy. This idea hinges on an unproved hypothesis: that zero-point energy is what keeps electrons in an atom orbiting the nucleus. In classical physics, circulating charges like an orbiting electron lose energy through radiation. Putoff believes that zero-point energy keeps the electron zipping around the nucleus (Quantum mechanics as originally formulated simply states that an electron in an atom must have some minimum, ground-state energy.)
Physicists have demonstrated that a small enough cavity can suppress the natural inclination of a trapped, excited particle to give up some energy and drop to a lower energy state [see "Cavity Quantum Electrodynamics," by Serge Haroche and Jean-Michel Raimond; Scientific American, April 1993]. Basically, the cavity is so small that it can exclude some of the lower-frequency vacuum fluctuations, which the excited atom needs to emit light and drop to a lower energy level. The cavity in effect controls the vacuum fluctuations.
Under the right circumstances, Puthoff reasons, one could effectively manipulate the vacuum so that a new, lower ground state appears. The electron would then drop to the lower ground state--in effect, the atom would become smaller--and give up some energy in the process.
"It implies that hydrogen or deuterium injected into cavities might produce excess energy," Puthoff says.
This possibility might explain some of the cold-fusion experiments, he notes--in other words, the occasional positive results reported in cold-fusion tests might really be indicators of zero-point energy (rather than, one would assume, wishful thinking). Work in cavity quantum electrodynamics is experimentally challenging in its own right, so it is not clear how practical an energy supply from "shrinking atoms" could be. The Austin institute is testing a device that could be interpreted as manipulating the vacuum. Puthoff, however, declines to provide details, citing a proprietary nondisclosure agreement with its designers.
Puthoff's institute receives a little government money but gets most of its funds from contracts with private firms. Others are backed more explicitly by public money. This past August the National Aeronautics and Space Administration sponsored a meeting called the "Breakthrough Propulsion Physics Workshop." According to participants, zero-point energy became a high priority among those trying to figure out which "breakthroughs" should be pursued.
The propulsion application depends on a speculation put forth in 1994 by Puthoff, Bernhard Haisch of Lockheed Palo Alto Research Laboratory and Alfonso Rueda of California State University at Long Beach. They suggested that inertia--the resistance that objects put up when they are accelerated--stems from the drag effects of moving through the zero-point field. Because the zero-point field can be manipulated in quantum experiments, Puthoff reasons, it should be possible to lessen an object's inertia and hence, for a rocket, reduce the fuel burden. Puthoff and his colleagues have been trying to prove this inertia-origin hypothesis--a sensitive pendulum should be able to detect a zero-point-energy "wake" left by a moving object--but Puthoff says they have not managed to isolate their system well enough to do so. More conventional scientists decried the channeling of NASA funds to a meeting where real science was lacking. "We hardly talked about the physics" of the proposals, complained Milonni, adding that during one of the breakout sessions "there was a guy talking about astral projection." Certainly, there should be room for far-out, potentially revolutionary ideas, but not at the expense of solid science. "One has to keep an open mind, but the concepts I've seen so far would violate energy conservation," Milonni concludes. In sizing up zero-point-energy schemes, it may be best to keep in mind the old caveat emptor: if it sounds too good to be true, it probably is.
References
Haisch in Feb 1994 Phys. Rev.A Science vol 263 p 612 Scientific American vol 270, p 30 New Scientist 25 Feb 1995 p 30
"Gravity as a Zero-Point-Fluctuation Force," H.E. Puthoff, Physical Review A: General Physics. Mar 1 1989, Vol39 No 5