253 research outputs found
Lorentz transformations of open systems
We consider open dynamical systems, subject to external interventions by
agents that are not completely described by the theory (classical or quantal).
These interventions are localized in regions that are relatively spacelike.
Under these circumstances, no relativistic transformation law exists that
relates the descriptions of the physical system by observers in relative
motion. Still, physical laws are the same in all Lorentz frames.Comment: Final version submitted to J. Mod. Opt. (Proc. of Gdansk conference
Compressing the hidden variable space of a qubit
In previously exhibited hidden variable models of quantum state preparation
and measurement, the number of continuous hidden variables describing the
actual state of a single realization is never smaller than the quantum state
manifold dimension. We introduce a simple model for a qubit whose hidden
variable space is one-dimensional, i.e., smaller than the two-dimensional Bloch
sphere. The hidden variable probability distributions associated with the
quantum states satisfy reasonable criteria of regularity. Possible
generalizations of this shrinking to a N-dimensional Hilbert space are
discussed.Comment: References updated and added some more discussions of result
Immanence in Physics
In this article, the conceptual history of space in physics will be presented in the context of transcendent and immanent concepts. In short, transcendent concepts postulate space as an ambient super-structure to organize material objects, while in immanent concepts space does not exist apart from objects but emerges through their relations. In this analysis it becomes apparent that transcendent characterizations of space have been dominant in physics during the past centuries, while immanent conceptions of space have come to the fore only since the development of the general theory of relativity. The importance of immanence in physics besides relativity is still lacking. In contrast to the classical framework of absolute and relative accounts of space, the notions of transcendence and immanence allow for a complementary conception of space which combines elements of both
General Relativity As an Aether Theory
Most early twentieth century relativists --- Lorentz, Einstein, Eddington,
for examples --- claimed that general relativity was merely a theory of the
aether. We shall confirm this claim by deriving the Einstein equations using
aether theory. We shall use a combination of Lorentz's and Kelvin's conception
of the aether. Our derivation of the Einstein equations will not use the
vanishing of the covariant divergence of the stress-energy tensor, but instead
equate the Ricci tensor to the sum of the usual stress-energy tensor and a
stress-energy tensor for the aether, a tensor based on Kelvin's aether theory.
A crucial first step is generalizing the Cartan formalism of Newtonian gravity
to allow spatial curvature, as conjectured by Gauss and Riemann
From Einstein's Theorem to Bell's Theorem: A History of Quantum Nonlocality
In this Einstein Year of Physics it seems appropriate to look at an important
aspect of Einstein's work that is often down-played: his contribution to the
debate on the interpretation of quantum mechanics. Contrary to popular opinion,
Bohr had no defence against Einstein's 1935 attack (the EPR paper) on the
claimed completeness of orthodox quantum mechanics. I suggest that Einstein's
argument, as stated most clearly in 1946, could justly be called Einstein's
reality-locality-completeness theorem, since it proves that one of these three
must be false. Einstein's instinct was that completeness of orthodox quantum
mechanics was the falsehood, but he failed in his quest to find a more complete
theory that respected reality and locality. Einstein's theorem, and possibly
Einstein's failure, inspired John Bell in 1964 to prove his reality-locality
theorem. This strengthened Einstein's theorem (but showed the futility of his
quest) by demonstrating that either reality or locality is a falsehood. This
revealed the full nonlocality of the quantum world for the first time.Comment: 18 pages. To be published in Contemporary Physics. (Minor changes;
references and author info added
On Locality in Quantum General Relativity and Quantum Gravity
The physical concept of locality is first analyzed in the special
relativistic quantum regime, and compared with that of microcausality and the
local commutativity of quantum fields. Its extrapolation to quantum general
relativity on quantum bundles over curved spacetime is then described. It is
shown that the resulting formulation of quantum-geometric locality based on the
concept of local quantum frame incorporating a fundamental length embodies the
key geometric and topological aspects of this concept. Taken in conjunction
with the strong equivalence principle and the path-integral formulation of
quantum propagation, quantum-geometric locality leads in a natural manner to
the formulation of quantum-geometric propagation in curved spacetime. Its
extrapolation to geometric quantum gravity formulated over quantum spacetime is
described and analyzed.Comment: Mac-Word file translated to postscript for submission. The author may
be reached at: [email protected] To appear in Found. Phys. vol. 27,
199
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