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Stochastic electrodynamics (SED) is a variant of classical electrodynamics (CED) of theoretical physics. SED consists of a set of controversial theories that posit the existence of a classical Lorentz invariant radiation field having statistical properties similar to that of the electromagnetic zero-point field (ZPF) of quantum electrodynamics (QED). Investigations of SED have been concerned with: # The degree to which this prescription might cause SED to mimic some behaviors traditionally considered to be the exclusive domain of quantum mechanics; and # A possible classical ZPF-based origin for gravity, inertia and the photoelectric effect. The reported results are subject to considerable argument. Even so, there is a fair amount of interest in SED as this suggests the possibility of anti-gravity, reactionless drives or free energy so claims for practical devices do occasionally appear. No practical devices have been publicly demonstrated or subjected to any universally agreed upon independent review. ==Classical background field== The background field is introduced as a Lorentz force in the (classical) Abraham-Lorentz-Dirac equation (see: Abraham–Lorentz–Dirac force), where the classical statistics of the electric and magnetic fields and quadratic combinations thereof are chosen to match the vacuum expectation values of the equivalent operators in QED. The field is generally represented as a discrete sum of Fourier components each with amplitude and phase that are independent classical random variables, distributed so that the statistics of the fields are isotropic and unchanged under boosts. This prescription is such that each Fourier mode at frequency (f) is expected to have an energy of hf/2, equaling that of the ground state of the vacuum modes of QED. Unless cut off, the total field has an infinite energy density, with a spectral energy density (per unit frequency per unit volume) ()f3 where h is Planck's constant. Consequently, the background field is a classical version of the electromagnetic ZPF of QED, though in SED literature the field is commonly referred to simply as 'the ZPF' without making that distinction. It should be noted that any finite cutoff frequency of the field itself would be incompatible with Lorentz invariance. For this reason, some researchers prefer to think of cutoff frequency in terms of the response of particles to the field rather than as a property the field itself. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「stochastic electrodynamics」の詳細全文を読む スポンサード リンク
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