292 research outputs found
Pure quantum freezing of the 5 dimension
It is shown that superthin and superlong gravitational flux tube solutions in
the 5D Kaluza-Klein gravity have the region where the metric
signature changes from to . Such change is too
quickly from one of the paradigms of quantum gravity which tells that the
Planck length is the minimal length in the nature and consequently the physical
quantities can not change very quickly in the course of this length. For
avoiding such dynamic it is supposed that a pure quantum freezing of the
dynamic of the dimension takes place. As the continuation of the flux
tube metric in the longitudinal direction the Reissner-Nordstr\"om metric is
proposed. In the consequence of such construction one can avoid the appearance
of a point-like singularity in the extremal Reissner-Nordstr\"om solution.Comment: grammar errors are correcte
Experimental test for 5th dimension in Kaluza-Klein gravity
Several electric/magnetic charged solutions (dyons) to 5D Kaluza-Klein
gravity on the principal bundle are reviewed. Here we examine the possibility
that these solutions can act as quantum virtual wormholes in spacetime foam
models. By applying a sufficently large, external electric and/or magnetic
field it may be possible to ``inflate'' these solutions from a quantum to a
classical state. This effect could lead to a possible experimental signal for
higher dimensions in multidimensional gravity.Comment: 4 pages, 4 figures, Talk given at the Third Meeting on Constrained
Dynamics and Quantum Gravity, Villasimius (Sardinia), September 13-17, 199
Spherically Symmetric solutions in Multidimensional Gravity with the SU(2) Gauge Group as the Extra Dimensions
The multidimensional gravity on the principal bundle with the SU(2) gauge
group is considered. The numerical investigation of the spherically symmetric
metrics with the center of symmetry is made. The solution of the gravitational
equations depends on the boundary conditions of the ``SU(2) gauge potential''
(off-diagonal metric components) at the symmetry center and on the type of
symmetry (symmetrical or antisymmetrical) of these potentials. In the chosen
range of the boundary conditions it is shown that there are two types of
solutions: wormhole-like and flux tube. The physical application of such kind
of solutions as quantum handles in a spacetime foam is discussed.Comment: misprints are correcte
Gravitational Flux Tubes
By studying multidimensional Kaluza-Klein theories, or gravity plus U(1) or
SU(2) gauge fields it is shown that these theories possess similar flux tube
solutions. The gauge field which fills the tube geometry of these solutions
leads to a comparision with the flux tube structures in QCD. These solutions
also carry a ``magnetic'' charge, Q, which for the SU(2) Einstein-Yang-Mills
(EYM) system exhibits a dual relationship with the Yang-Mills gauge coupling,
g, (). As or , or
respectively. Thus within this classical EYM field theory we find solutions
which have features - flux tubes, magnetic charges, large value of the gauge
coupling - that are similar to the key ingredients of confinement in QCD.Comment: REVTEX, 12 p
Reparametrization-Invariant Path Integral in GR and "Big Bang" of Quantum Universe
The reparametrization-invariant generating functional for the unitary and
causal perturbation theory in general relativity in a finite space-time is
obtained. The region of validity of the Faddeev-Popov-DeWitt functional is
studied. It is shown that the invariant content of general relativity as a
constrained system can be covered by two "equivalent" unconstrained systems:
the "dynamic" (with "dynamic" evolution parameter as the metric scale factor)
and "geometric" (given by the Levi-Civita type canonical transformation to the
action-angle variables where the energy constraint converts into a new
momentum). "Big Bang", the Hubble evolution, and creation of matter fields by
the "geometric" vacuum are described by the inverted Levi-Civita (LC)
transformation of the geomeric system into the dynamic one. The particular case
of the LC transformations are the Bogoliubov ones of the particle variables
(diagonalizing the dynamic Hamiltonian) to the quasiparticles (diagonalizing
the equations of motion). The choice of initial conditions for the "Big Bang"
in the form of the Bogoliubov (squeezed) vacuum reproduces all stages of the
evolution of the Friedmann-Robertson-Walker Universe in their conformal
(Hoyle-Narlikar) versions.Comment: 21 pages, latex, 4 figures in postscrip
Cylindrically symmetric, static strings with a cosmological constant in Brans-Dicke theory
The static, cylindrically symmetric vacuum solutions with a cosmological
constant in the framework of the Brans-Dicke theory are investigated. Some of
these solutions admitting Lorentz boost invariance along the symmetry axis
correspond to local, straight cosmic strings with a cosmological constant. Some
physical properties of such solutions are studied. These strings apply
attractive or repulsive forces on the test particles. A smooth matching is also
performed with a recently introduced interior thick string solution with a
cosmological constant.Comment: 8 pages, Revtex; Published versio
Dynamic resources of the SanitĂ spring at Caposele (South Italy)
The SanitĂ Spring at Caposele (NE of Campania â South Italy) is the main spring of the Sele river. Since the end of '800, it was indicated and was prospected as the possible base of the Acquedotto Pugliese for drinking the dry Apulia zone. The spring was effective tapped in 1911. A research on the source dynamic resources was began to start in 2009 and is terminated today on the base of data collected of Spring discharge during more of 100 y. A great quantities of specific work about the Spring are collected since the last occur in the Cervialto massif (the cross gallery to connect to Aqueduct the Sorbo Serpico springs). The hydrogeological characteristics of the massif was surveyed and a hydrogeological map was completed. The everyday discharge data are studied with numerous mathematic models of the SanitĂ empting curves. The models, prepared for the tapping work management, gain to divide the spring trend in various operative cycles and in two different kind of the emptying curves, everyone exanimated and modulated. The research produce relevant conclusions to the actual tapping work and their protection areas against pollution. This work is concluded by a complete discussion of research finality and the models utilized for a complete operation by tapping work operator
Experimental test for extra dimensions in Kaluza-Klein gravity
5D Kaluza-Klein gravity has several nonasymptotically flat solutions which
generally, possessed both electric and magnetic charges. In this paper we
suggest that these solutions can act as quantum virtual handles (wormholes) in
spacetime foam models. By applying a sufficently large, external electric
and/or magnetic field it may be possible to ``inflate'' these solutions from a
quantum to a classical state. This effect would lead to a possible experimental
signal for higher dimensions in multidimensional gravity.Comment: 11 pages, 3 PS.figures, REVTEX, the quality of the figures are
improve
Melvin universe as a limit of the C-metric
It is demonstrated that the Melvin universe representing the spacetime with a
strong 'homogeneous' electric field can by obtained from the spacetime of two
accelerated charged black holes by a suitable limiting procedure. The behavior
of various invariantly defined geometrical quantities in this limit is also
studied.Comment: 5 pages, no figures [v2: two references added
Soft singularity and the fundamental length
It is shown that some regular solutions in 5D Kaluza-Klein gravity may have
interesting properties if one from the parameters is in the Planck region. In
this case the Kretschman metric invariant runs up to a maximal reachable value
in nature, i.e. practically the metric becomes singular. This observation
allows us to suppose that in this situation the problems with such soft
singularity will be much easier resolved in the future quantum gravity then by
the situation with the ordinary hard singularity (Reissner-Nordstr\"om
singularity, for example). It is supposed that the analogous consideration can
be applied for the avoiding the hard singularities connected with the gauge
charges.Comment: 5 page
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