725 research outputs found
Synchronization Gauges and the Principles of Special Relativity
The axiomatic bases of Special Relativity Theory (SRT) are thoroughly
re-examined from an operational point of view, with particular emphasis on the
status of Einstein synchronization in the light of the possibility of arbitrary
synchronization procedures in inertial reference frames. Once correctly and
explicitly phrased, the principles of SRT allow for a wide range of `theories'
that differ from the standard SRT only for the difference in the chosen
synchronization procedures, but are wholly equivalent to SRT in predicting
empirical facts. This results in the introduction, in the full background of
SRT, of a suitable synchronization gauge. A complete hierarchy of
synchronization gauges is introduced and elucidated, ranging from the useful
Selleri synchronization gauge (which should lead, according to Selleri, to a
multiplicity of theories alternative to SRT) to the more general Mansouri-Sexl
synchronization gauge and, finally, to the even more general
Anderson-Vetharaniam-Stedman's synchronization gauge. It is showed that all
these gauges do not challenge the SRT, as claimed by Selleri, but simply lead
to a number of formalisms which leave the geometrical structure of Minkowski
spacetime unchanged. Several aspects of fundamental and applied interest
related to the conventional aspect of the synchronization choice are discussed,
encompassing the issue of the one-way velocity of light on inertial and
rotating reference frames, the GPS's working, and the recasting of Maxwell
equations in generic synchronizations. Finally, it is showed how the gauge
freedom introduced in SRT can be exploited in order to give a clear explanation
of the Sagnac effect for counter-propagating matter beams.Comment: 56 pages, 3 eps figures, invited paper; to appear in Foundations of
Physics (Special Issue to honor Prof. Franco Selleri on his 70th birthday
A Derivation of Three-Dimensional Inertial Transformations
The derivation of the transformations between inertial frames made by
Mansouri and Sexl is generalised to three dimensions for an arbitrary direction
of the velocity. Assuming lenght contraction and time dilation to have their
relativistic values, a set of transformations kinematically equivalent to
special relativity is obtained. The ``clock hypothesis'' allows the derivation
to be extended to accelerated systems. A theory of inertial transformations
maintaining an absolute simultaneity is shown to be the only one logically
consistent with accelerated movements. Algebraic properties of these
transformations are discussed. Keywords: special relativity, synchronization,
one-way velocity of light, ether, clock hypothesis.Comment: 16 pages (A5), Latex, one figure, to be published in Found. Phys.
Lett. (1997
Does Clauser-Horne-Shimony-Holt Correlation or Freedman-Clauser Correlation lead to the largest violation of Bell's Inequality?
An inequality is deduced from Einstein's locality and a supplementary
assumption. This inequality defines an experiment which can actually be
performed with present technology to test local realism. Quantum mechanics
violate this inequality a factor of 1.5. In contrast, quantum mechanics
violates previous inequalities (for example, Clauser-Horne-Shimony-Holt
inequality of 1969, Freedman-Clauser inequality of 1972, Clauser-Horne
inequality of 1974) by a factor of . Thus the magnitude of violation
of the inequality derived in this paper is approximately larger than
the magnitude of violation of previous inequalities. This result can be
particularly important for the experimental test of locality.Comment: 15 pages, LaTeX file, no figure
A comparison between standard and crossfeed monopulse radars in presence of rough sea scattering and ship movements
Monopulse radars are widely used in tracking systems, due to their relative
simplicity and theoretical precision, but the presence of multipath
impairs the tracking capabilities of these radars, especially when multipath
signals are strong, as in a naval environment. A special monopulse
setup, the crossfeed, has been proposed in the past to provide an automatic
cancellation from smooth sea multipath. In this contribution,
the performances of such a system are analyzed in presence of rough sea
scattering and compared with those of a standard monopulse setup. Particular
attention is devoted to performance degradations due to possible
phase errors in the passive network implementing the comparator and
due to ship rolling and pitching. This latter requires a full 3D monopulse
simulator for its correct evaluation
Time on a Rotating Platform
Traditional clock synchronisation on a rotating platform is shown to be
incompatible with the experimentally established transformation of time. The
latter transformation leads directly to solve this problem through noninvariant
one-way speed of light. The conventionality of some features of relativity
theory allows full compatibility with existing experimental evidence.Comment: 12 pages, Latex, no figure. Copies available at [email protected]
accepted for publication in Found. Phys. Let
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