Friction and inertia for a mirror in a thermal field

The force experienced by a mirror moving in vacuum vanishes in the case of uniform velocity or uniform acceleration, as a consequence of spatial symmetries of vacuum. These symmetries do not subsist in a thermal field. We give a general expression of the corresponding viscosity coefficient valid at any temperature and for any reflectivity function. We show that the computed motional force also contains a non vanishing inertial term. The associated mass correction goes to zero in the limiting cases of perfect reflection or of zero temperature.Comment: 5 page

Quantum Fluctuations of Mass for a Mirror in Vacuum

A mirror in vacuum is coupled to fluctuating quantum fields. As a result, its energy-momentum and mass fluctuate. We compute the correlation spectra of force and mass fluctuations for a mirror at rest in vacuum (of a scalar field in a two-dimensional space-time). The obtained expressions agree with a mass correction equal to a vacuum energy stored by the mirror. We introduce a Lagrangian model which consistently describes a scalar field coupled to a scatterer, with inertial mass being a quantum variable.Comment: 6 page

Observable Dirac Electron in Accelerated Frames

We present a new quantum algebraic description of an electron localized in space-time. Positions in space and time, mass and Clifford generators are defined as quantum operators. Commutation relations and relativistic shifts under frame transformations are determined within a unique algebraic framework. Redshifts, i.e. shifts under transformations to uniformly accelerated frames, are evaluated and found to differ from the expressions of classical relativity.Comment: 7 pages, revised versio

Causality, stability and passivity for a mirror in vacuum

The mean force exerted upon a perfect mirror moving in vacuum in a two dimensional spacetime has the same expression as the radiation reaction force computed in classical electron theory. It follows that unacceptable runaway solutions are predicted. We show that this instability problem does not appear when partially transmitting mirrors are studied. The mechanical impedance describing the mirror coupled to vacuum radiation pressure is computed explicitly; recoil is neglected. It is found to be a passive function, so that stability is ensured. This is connected to the fact that no energy can be extracted from the vacuum state.Comment: 5 pages, corrected typo in formula

Gravity tests in the solar system and the Pioneer anomaly

We build up a new phenomenological framework associated with a minimal generalization of Einsteinian gravitation theory. When linearity, stationarity and isotropy are assumed, tests in the solar system are characterized by two potentials which generalize respectively the Newton potential and the parameter $\gamma$ of parametrized post-Newtonian formalism. The new framework seems to have the capability to account for the Pioneer anomaly besides other gravity tests.Comment: 5 pages. Accepted version, to appear in Modern Physics Letters

Gravitational Quantum Limit for Length Measurements

We discuss a limit for sensitivity of length measurements which is due to the effect of vacuum fluctuations of gravitational field. This limit is associated with irreducible quantum fluctuations of geodesic distances and it is characterized by a noise spectrum with an order of magnitude mainly determined by Planck length. The gravitational vacuum fluctuations may (in an analysis restricted to questions of principle and when the measurement strategy is optimized) dominate fluctuations added by the measurement apparatus if macroscopic masses, i.e. masses larger than Planck mass, are used.Comment: 6 page

Quantum Langevin Equations and Stability

Different quantum Langevin equations obtained by coupling a particle to a field are examined. Instabilities or violations of causality affect the motion of a point charge linearly coupled to the electromagnetic field. In contrast, coupling a scatterer with a reflection cut-off to radiation pressure leads to stable and causal motions. The radiative reaction force exerted on a scatterer, and hence its quasistatic mass, depend on the field state. Explicit expressions for a particle scattering a thermal field in a two dimensional space-time are given.Comment: 12 page