Showing papers on "Initial singularity published in 1980"
TL;DR: The physical interpretation of perturbations of homogeneous, isotropic cosmological models in the early Universe, when the perturbation is larger than the particle horizon, is clarified by defining a complete set of gauge-invariant variables as discussed by the authors.
Abstract: The physical interpretation of perturbations of homogeneous, isotropic cosmological models in the early Universe, when the perturbation is larger than the particle horizon, is clarified by defining a complete set of gauge-invariant variables. The linearized perturbation equations written in these variables are simpler than the usual versions, and easily accommodate an arbitrary background equation of state, entropy perturbations, and anisotropic pressure perturbations. Particular attention is paid to how a scalar (density) perturbation might be generated by stress perturbations at very early times, when the non-gauge-invariant perturbation in the density itself is ill-defined. The amplitude of the fractional energy density perturbation at the particle horizon cannot be larger, in order of magnitude, than the maximum ratio of the stress perturbation to the background energy density at any earlier time, unless the perturbation is inherent in the initial singularity.
2,114 citations
TL;DR: In this paper, a generalised Friedman equation for a homogeneous isotropic cosmology is obtained, including terms in the lagrangian quadratic in the curvature and torsion tensors.
74 citations
Journal Article•
TL;DR: In this article, a quantum theory of adiabatic perturbations of matter in the Friedman cosmology is formulated, and it is shown that the mechanism of spontaneous phonon production near a cosmological singularity can lead to formation of the initial spectrum of ADIABACs of matter.
Abstract: A quantum theory of adiabatic perturbations of matter in the Friedman cosmology is formulated. It is shown that the mechanism of spontaneous phonon production near a cosmological singularity can lead to formation of the initial spectrum of adiabatic perturbations of matter.
36 citations
TL;DR: In this article, the particle interpretation of quantised fields in homogeneous isotropic space-time is given which is based on the diagonalisation of the Hamiltonian constructed via the metrical stress-energy tensor (SET).
Abstract: The particle interpretation of quantised fields in homogeneous isotropic space-time is given which is based on the diagonalisation of the Hamiltonian constructed via the metrical stress-energy tensor (SET). This interpretation and the regularisation procedure of Zeldovich and Starobinsky (1971) allows one to obtain the total renormalised vacuum expectation values of SET which include both vacuum polarisation and non-local terms describing the creation of particles. The case of the explicitly soluble cosmological model with initial singularity which is asymptotically static in the future is considered. The results of the calculation of the total SET in realistic Friedman cosmological models are presented.
28 citations
TL;DR: In this paper, a new exact solution of the massless-scalar-field equations was constructed, which corresponds to an inhomogeneous closed universe filled with scalar, gravitational, and electromagnetic waves.
Abstract: Following Gowdy, Berger, and Misner we construct a new exact solution of the Einstein--Maxwell--massless-scalar-field equations which corresponds to an inhomogeneous closed universe filled with scalar, gravitational, and electromagnetic waves. It is obtained as a result of homogeneity breaking in the corresponding Bianchi type-I universe. The combined effect of the scalar and vector fields on the dynamics of the evolution process and the interactions between the fields involved are systematically investigated. The structure of the initial singularity is studied in detail in both the homogeneous and inhomogeneous cases. The final stage of evolution is studied and interpreted in terms of the quanta of scalar, gravitational, and electromagnetic fields. Possible extensions of the present model to the conformally coupled scalar field and the Abelian solutions of the Yang-Mills field equations are pointed out.
12 citations
TL;DR: In this article, the number of gravitons, photons, and scalar mesons is defined in terms of particle numbers in the WKB limit, and the parameters which define the numbers of particles in each normal mode are further related to the quantities which characterize the behavior of gravitational, scalar, and electromagnetic fields in the vicinity of the initial singularity.
Abstract: Gowdy universes with scalar and electromagnetic fields are reconsidered. The numbers of gravitons, photons, and scalar mesons are introduced in the WKB limit. The WKB metric functions are subsequently rewritten in terms of particle numbers. The parameters which define the number of particles in each normal mode are further related to the quantities which characterize the behavior of gravitational, scalar, and electromagnetic fields in the vicinity of the initial singularity.
3 citations
TL;DR: The requirement that A(r) (the coefficient of dt/sup 2/ in the general form of the point-mass metric) vanish as r ..-->.. 0 is unnecessary to secure the inextendability of the metric to r=0, but the requirement must still be maintained in order to ensure that the singularity at r-0 is mass related.
Abstract: The requirement that A(r) (the coefficient of dt/sup 2/ in the general form of the point-mass metric) vanish as r ..-->.. 0 is unnecessary to secure the inextendability of the metric to r=0. However, the requirement must still be maintained in order to ensure that the singularity at r=0 is mass related.
3 citations
TL;DR: In this paper, an elementary introduction is given to the quantum processes which are now being invoked to resolve the problems of the big bang itself, including the origin and isotropy of the 3° K background, the baryon asymmetry of the universe, and eliminating the singularity which present theory requires for the Big Bang itself.
Abstract: Quantum processes occurring within 10-43 s of the big bang may be responsible for the origin and isotropy of the 3° K background, for the presumed baryon asymmetry of the universe, and for eliminating the singularity which present theory requires for the big bang itself. An elementary introduction is given to the quantum processes which are now being invoked to resolve these problems.
3 citations
TL;DR: In this paper, it is shown that for a closed universe with any distribution of matter whatsoever there occurred a singularity in the past in the nonrotating parts of the universe and it must recur in the future.
Abstract: Recently Addy and Datta have obtained a linearized solution for isentropic motions of a perfect fluid by assigning Cauchy data on the hypersurfacex4=0 and by imposing a restriction on the equation of state. In the present paper we pursue this study and discuss the problem of singularities from the standpoint of a local observer for which a singularity is defined as a state with an infinite proper rest mass density. It is shown that for a closed universe with any distribution of matter whatsoever there occurred a singularity in the past in the nonrotating parts of the universe and it must recur in the future. Furthermore, the collapse of a rotating fluid to a singularity seems inevitable when the relativistic equation of state is considered.
1 citations