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This Defense Intelligence Reference Document from the Defense Intelligence Agency, dated 6 April 2010, is one in a series of FY 2009 advanced technology reports produced under the Advanced Aerospace Weapon System Applications (AAWSA) program. It reviews the physics of zero-point field energy in the quantum vacuum and proposed schemes for extracting it, including the Casimir effect, Forward's vacuum-fluctuation battery, and resonant dielectric spheres. It notes that no practicable extraction technique has been demonstrated in the laboratory.
“The Advance”4 pages
UNCLASSIFIED/ ,'1"1!11'- 81"1"11!1*1. Wlilii liUllolC defined to have vanishing energy density, any region with less energy density than the vacuum actually has a negative (renormalized) expectation value for the energy density - hence, this is a degradable vacuum. Therefore, a squeezed vacuum state consists of a traveling electromagnetic wave that oscillates back and forth between negative energy density and positive energy density, but has positive time-averaged energy density. For the squeezed electromagnetic vacuum state, the energy density p1,-,4vac is given by (Reference 102): PF-,qv,ic· = ( 2 ~/" }inh ~[ sinh ~ +cosh ~cos(2w(I - z I c) + 6)] (J / m') ( 6) where L3 is the volume of a large box with sides of length L (that is, put the quantum field in a box with periodic boundary conditions), Sis the squeezed state amplitude (giving a measure of the mean photon number in a squeezed state), and o is the phase of squeezing. Equation (6) shows that pi-.-, 4vac falls below zero once every cycle when the condition cosh S > sinh S is met. It turns out that this is always true for every nonzero value of S, so pL 4,."· becomes negative at some point in the cycle for a general squeezed vacuum state. On another note, when a quantum state is close to a squeezed vacuum state, there will almost always be some negative vacuum energy densities present. Dirac Vacuum Decay: "Sparking the Vacuum" Fulcher et al. (Reference 53), Rafelski and MUiier (Reference 54), and Rafelski (Reference 55) describe a phenomenon whereby the QED vacuum 17 behaves like a nonlinear dielectric medium and undergoes breakdown (or decay) in the vicinity of super-heavy (supercritical) atomic nuclei 18 or in the presence of externally applied electric or magnetic fields of critical (or supercritical) strength. 19 This decay results in the spontaneous production of electron-positron pairs from the vacuum. This phenomenon is known as the Heisenberg-Euler-Schwinger mechanism, which Rafelski and collaborators euphemistically call "sparking the vacuum." Ringwald (Reference 104) prefers to call it "boiling the vacuum." Supercritical atomic nuclei can be created by the slow collision of two uranium (or heavier) nuclei while critical/supercritical electric or magnetic fields can be produced by ultrahigh intensity chirped-pulse amplification lasers (with power intensities on the order of 10 19 to 1030 W1m 2). To be more precise, when an electric field is made sufficiently strong so that the vacuum polarization (that is, virtual electron-positron pairs, aka ZPF) becomes real, then, due to charge conservation, the balancing charge must be eliminated, and so during the process of changing the vacuum from a neutral to a charged state, some charge must be emitted. And if in the vicinity of the electric field of a super-heavy nucleus or of an externally applied electric or magnetic field, the vacuum carries the charge of an electron, the emitted particle must always be a positron. Studies have 17 For historical reasons, the QED vacuum is also called the "Dirac sea" or "Dirac vacuum" (Reference 103). 18 Supercritical atomic nuclei have an electric charge (proton number) of Z > 173, which produces supercritical electric fields. 19 The critical QED vacuum breakdown electric field strength is F," = 2m}c 3/rie"' 10 18 V/m, where e is the electron charge (1.602 x 10 19 C). This quantity is defined by the total rest-energy of an electron-positron pair created from the vacuum divided by the electron's Compton wavelength. And the critical QED vacuum breakdown magnetic field strength is Be=- EJc"' 10 10 Tesla. Supercritical fields have strengths greater than£,. or Be-. 33 UNCLASSIFIED/ )f81il 8ffl@Itllt ~:!II!! 8HLV
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