Josep Maria Pons
Current Organizations / Institutes
The organizations/institutes from the scholar's latest article
Previous Organizations / Institutes
The organizations / institutes from the scholar's other articles in the past ten years
Research Subjects
Research Interests
Josep Maria Pons has a total of 72 co-authors. Here are the top co-authors by number of shared publications:
- Naresh Dadhich
Inter University Centre for Astronomy & Astrophysics Post Bag 4 411007 Pune India
14 shared publications - Joaquim Gomis
Universitat de Barcelona
13 shared publications - Xavier Gràcia
Department of Mathematics Universitat Politècnica de Catalunya Barcelona Catalonia Spain
11 shared publications L. C. Shepley
The University of Texas
10 shared publications- Donald C. Salisbury
Department of Physics Austin College 75090-4440 Sherman Texas USA
6 shared publications - Donald Salisbury
Austin College, Sherman, USA
6 shared publications
Latest Publications
- Open Access
- 19 November 2021
- Published by Springer Nature in General Relativity and Gravitation
- Vol. 53 (11) , 1-24
On cosmological expansion and local physics
We find an exact convergence in the local dynamics described by two supposedly antagonistic approaches applied at the local, solar system scale: one starting from an expanding universe perspective such as FLRW, the other based on a local model ignoring any notion of expansion, such as static Schwarzschild dS. Both models are in complete agreement when the local effects of the expansion are circumscribed to the presence of the cosmological constant. We elaborate on the relevant role of static backgrounds like the Schwarzschild-dS metric in standard form as the most proper coordinatizations to describe physics at the local scale. We also elaborate on the popular expanding 3-space picture—to be distinguished from that of the expanding universe—and point out the confusion of scales which is typically associated with it. Finally, making use of an old and too often forgotten relativistic kinematical invariant, we address some remaining misunderstandings on space expansion, cosmological and gravitational redshifts. As a byproduct we propose a unique and unambiguous prescription to match the local and cosmological expression of a specific observable.
- 19 November 2021
- Published by Springer Nature in General Relativity and Gravitation
- Vol. 53 (11) , 1-24
Open AccessOn cosmological expansion and local physics
We find an exact convergence in the local dynamics described by two supposedly antagonistic approaches applied at the local, solar system scale: one starting from an expanding universe perspective such as FLRW, the other based on a local model ignoring any notion of expansion, such as static Schwarzschild dS. Both models are in complete agreement when the local effects of the expansion are circumscribed to the presence of the cosmological constant. We elaborate on the relevant role of static backgrounds like the Schwarzschild-dS metric in standard form as the most proper coordinatizations to describe physics at the local scale. We also elaborate on the popular expanding 3-space picture—to be distinguished from that of the expanding universe—and point out the confusion of scales which is typically associated with it. Finally, making use of an old and too often forgotten relativistic kinematical invariant, we address some remaining misunderstandings on space expansion, cosmological and gravitational redshifts. As a byproduct we propose a unique and unambiguous prescription to match the local and cosmological expression of a specific observable.
- Open Access
On cosmological expansion and local physics
We find an exact convergence in the local dynamics described by two supposedly antagonistic approaches in modern cosmology: one starting from an expanding universe perspective such as FLRW, the other based on a local model ignoring any notion of expansion, such as Schwarzschild dS. Both models are in complete agreement when the local effects of the expansion are circumscribed to the presence of the cosmological constant. We elaborate in the relevant role of static backgrounds like the Schwarzschild-dS metric in standard form as the most proper coordinatizations to describe physics at the local scale. Finally, making use of an old and too often forgotten relativistic kinematical invariant, we clarify some widespread misunderstandings on space expansion, cosmological and gravitational redshifts. As a byproduct we propose a {\sl unique and unambiguous} prescription to match the local and cosmological expression of a specific observable.
Open AccessOn cosmological expansion and local physics
We find an exact convergence in the local dynamics described by two supposedly antagonistic approaches in modern cosmology: one starting from an expanding universe perspective such as FLRW, the other based on a local model ignoring any notion of expansion, such as Schwarzschild dS. Both models are in complete agreement when the local effects of the expansion are circumscribed to the presence of the cosmological constant. We elaborate in the relevant role of static backgrounds like the Schwarzschild-dS metric in standard form as the most proper coordinatizations to describe physics at the local scale. Finally, making use of an old and too often forgotten relativistic kinematical invariant, we clarify some widespread misunderstandings on space expansion, cosmological and gravitational redshifts. As a byproduct we propose a {\sl unique and unambiguous} prescription to match the local and cosmological expression of a specific observable.
- 26 June 2019
- Published by Springer Nature in General Relativity and Gravitation
- Vol. 51 (6) , 80
Observers with constant proper acceleration, constant proper Jerk, and beyond
- 26 June 2019
- Published by Springer Nature in General Relativity and Gravitation
- Vol. 51 (6) , 80
Observers with constant proper acceleration, constant proper Jerk, and beyond
- Open Access
Observers with constant proper acceleration, constant proper jerk, and beyond
We discuss in Minkowski spacetime the differences between the concepts of constant proper $n$-acceleration and of vanishing $(n+1)$-acceleration. By $n$-acceleration we essentially mean the higher order time derivatives of the position vector of the trajectory of a point particle, adapted to Minkowski spacetime or eventually to curved spacetime. The $2$-acceleration is known as the Jerk, the $3$-acceleration as the Snap, etc. As for the concept of {\sl proper} $n$-acceleration we give a specific definition involving the instantaneous comoving frame of the observer and we discuss, in such framework, the difficulties in finding a characterization of this notion as a Lorentz invariant statement. We show how the Frenet-Serret formalism helps to address the problem. In particular we find that our definition of an observer with constant proper acceleration corresponds to the vanishing of the third curvature invariant $\kappa_3$ (thus the motion is three dimensional in Minkowski spacetime) together with the constancy of the first and second curvature invariants and the restriction $\kappa_2 < \kappa_1$, the particular case $\kappa_2=0$ being the one commonly referred to in the literature. We generalize these concepts to curved spacetime, in which the notion of trajectory in a plane is replaced by the vanishing of the second curvature invariant $\kappa_2$. Under this condition, the concept of constant proper $n$-acceleration coincides with that of the vanising of the $(n+1)$-acceleration and is characterized by the fact that the first curvature invariant $\kappa_1$ is a $(n-1)$-degree polynomial of proper time. We illustrate some of our results with examples in Minkowski, de Sitter and Schwarzschild spacetimes.Open AccessObservers with constant proper acceleration, constant proper jerk, and beyond
We discuss in Minkowski spacetime the differences between the concepts of constant proper $n$-acceleration and of vanishing $(n+1)$-acceleration. By $n$-acceleration we essentially mean the higher order time derivatives of the position vector of the trajectory of a point particle, adapted to Minkowski spacetime or eventually to curved spacetime. The $2$-acceleration is known as the Jerk, the $3$-acceleration as the Snap, etc. As for the concept of {\sl proper} $n$-acceleration we give a specific definition involving the instantaneous comoving frame of the observer and we discuss, in such framework, the difficulties in finding a characterization of this notion as a Lorentz invariant statement. We show how the Frenet-Serret formalism helps to address the problem. In particular we find that our definition of an observer with constant proper acceleration corresponds to the vanishing of the third curvature invariant $\kappa_3$ (thus the motion is three dimensional in Minkowski spacetime) together with the constancy of the first and second curvature invariants and the restriction $\kappa_2 < \kappa_1$, the particular case $\kappa_2=0$ being the one commonly referred to in the literature. We generalize these concepts to curved spacetime, in which the notion of trajectory in a plane is replaced by the vanishing of the second curvature invariant $\kappa_2$. Under this condition, the concept of constant proper $n$-acceleration coincides with that of the vanising of the $(n+1)$-acceleration and is characterized by the fact that the first curvature invariant $\kappa_1$ is a $(n-1)$-degree polynomial of proper time. We illustrate some of our results with examples in Minkowski, de Sitter and Schwarzschild spacetimes. - Open Access
- 6 July 2018
- Published by IOP Publishing in Classical and Quantum Gravity
- Vol. 35 (15) , 155014
Noether symmetries for fields and branes in backgrounds with Killing vectors
Within the formulation of classical fields and branes in curved spacetime, we first discuss the Belinfante construction of an improved energy-momentum tensor density in curved backgrounds, in analogy to the case of flat spacetime. A novelty of our approach is the use of Noether identities for generally covariant theories as a guiding instrument. In this part of the paper, our basic results, which hold irrespective of the background being dynamical or fixed, agree with those previously obtained in Gamboa Saravi (2004 J. Phys. A: Math. Gen . 37 9573). We illustrate with the example of Maxwell theory the role played by the Belinfante tensor in the construction of the Noether conserved currents and symmetry generators associated with the Killing symmetries of the background, which become Noether symmetres for the matter Lagrangian. We also give some details on the existing obstructions to the realization of part of these symmetries in phase space. Next we study extended objects ( p -branes) either in a dynamic or in a fixed background, and obtain the Noether identities associated both with target spacetime and world volume diffeomorphisms. We show that in field theory as well as with extended objects, the Killing symmetries of the background become ordinary rigid Noether symmetries of the theory in this fixed background.
- 6 July 2018
- Published by IOP Publishing in Classical and Quantum Gravity
- Vol. 35 (15) , 155014
Open AccessNoether symmetries for fields and branes in backgrounds with Killing vectors
Within the formulation of classical fields and branes in curved spacetime, we first discuss the Belinfante construction of an improved energy-momentum tensor density in curved backgrounds, in analogy to the case of flat spacetime. A novelty of our approach is the use of Noether identities for generally covariant theories as a guiding instrument. In this part of the paper, our basic results, which hold irrespective of the background being dynamical or fixed, agree with those previously obtained in Gamboa Saravi (2004 J. Phys. A: Math. Gen . 37 9573). We illustrate with the example of Maxwell theory the role played by the Belinfante tensor in the construction of the Noether conserved currents and symmetry generators associated with the Killing symmetries of the background, which become Noether symmetres for the matter Lagrangian. We also give some details on the existing obstructions to the realization of part of these symmetries in phase space. Next we study extended objects ( p -branes) either in a dynamic or in a fixed background, and obtain the Noether identities associated both with target spacetime and world volume diffeomorphisms. We show that in field theory as well as with extended objects, the Killing symmetries of the background become ordinary rigid Noether symmetries of the theory in this fixed background.
- 16 November 2017
- Published by World Scientific Pub Co Pte Ltd
- p. 1834-1839
Static black hole solutions with horizon topology S(n) × S(n) for pure Lovelock theories
- 16 November 2017
- Published by World Scientific Pub Co Pte Ltd
- p. 1834-1839
Static black hole solutions with horizon topology S(n) × S(n) for pure Lovelock theories
- 26 October 2017
- Published by American Physical Society (APS) in Physical Review D
- Vol. 96 (8) , 084058
Generalized Gödel universes in higher dimensions and pure Lovelock gravity
The Gödel universe is a homogeneous rotating dust with negative which is a direct product of a three-dimensional pure rotation metric with a line. We would generalize it to higher dimensions for Einstein and pure Lovelock gravity with only one th-order term. For higher-dimensional generalization, we have to include more rotations in the metric, and hence we shall begin with the corresponding pure rotation odd -dimensional metric involving rotations, which eventually can be extended by a direct product with a line or a space of constant curvature for yielding a higher-dimensional Gödel universe. The considerations of rotations and also of constant curvature spaces is a new line of generalization and is being considered for the first time.- 26 October 2017
- Published by American Physical Society (APS) in Physical Review D
- Vol. 96 (8) , 084058
Generalized Gödel universes in higher dimensions and pure Lovelock gravity
The Gödel universe is a homogeneous rotating dust with negative which is a direct product of a three-dimensional pure rotation metric with a line. We would generalize it to higher dimensions for Einstein and pure Lovelock gravity with only one th-order term. For higher-dimensional generalization, we have to include more rotations in the metric, and hence we shall begin with the corresponding pure rotation odd -dimensional metric involving rotations, which eventually can be extended by a direct product with a line or a space of constant curvature for yielding a higher-dimensional Gödel universe. The considerations of rotations and also of constant curvature spaces is a new line of generalization and is being considered for the first time.- Open Access
Noether symmetries for fields and branes in backgrounds with Killing vectors
We show that Belinfante construction of an improved energy-momentum tensor can be carried over to curved backgrounds, in analogy to the case of flat spacetime. The results hold irrespective of the background being dynamical or a fixed, non-backreacting one. It turns out that the analogous would-be canonical energy-momentum tensor is not covariantly conserved in general, but its Belinfante "improvement" is. We relate this last tensor with the Hilbert tensor obtained by functionally derivating the Lagrangian with respect to the metric. When the background in non-dynamical, we discuss some issues concerning the Noether conserved currents associated with its Killing symmetries and the role played by the Belinfante tensor. Next we study extended objects ($p$-branes) either in a dynamic or in a fixed background, and obtain the Noether identities associated both with target spacetime and world volume diffeomorphisms. We show that in field theory as well as with extended objects, the Killing symmetries of the background become ordinary rigid Noether symmetries of the theory in this fixed background. With the example of Maxwell theory in Minkowski spacetime we show in an appendix the role of the Belinfante tensor in the construction of these symmetries.
Open AccessNoether symmetries for fields and branes in backgrounds with Killing vectors
We show that Belinfante construction of an improved energy-momentum tensor can be carried over to curved backgrounds, in analogy to the case of flat spacetime. The results hold irrespective of the background being dynamical or a fixed, non-backreacting one. It turns out that the analogous would-be canonical energy-momentum tensor is not covariantly conserved in general, but its Belinfante "improvement" is. We relate this last tensor with the Hilbert tensor obtained by functionally derivating the Lagrangian with respect to the metric. When the background in non-dynamical, we discuss some issues concerning the Noether conserved currents associated with its Killing symmetries and the role played by the Belinfante tensor. Next we study extended objects ($p$-branes) either in a dynamic or in a fixed background, and obtain the Noether identities associated both with target spacetime and world volume diffeomorphisms. We show that in field theory as well as with extended objects, the Killing symmetries of the background become ordinary rigid Noether symmetries of the theory in this fixed background. With the example of Maxwell theory in Minkowski spacetime we show in an appendix the role of the Belinfante tensor in the construction of these symmetries.
- Open Access
Generalized Gödel universes in higher dimensions and pure Lovelock gravity
G\"{o}del universe is a homogeneous rotating dust with negative $\Lambda$ which is a direct product of three dimensional pure rotation metric with a line. We would generalize it to higher dimensions for Einstein and pure Lovelock gravity with only one $N$th order term. For higher dimensional generalization, we have to include more rotations in the metric, and hence we shall begin with the corresponding pure rotation odd $(d=2n+1)$-dimensional metric involving $n$ rotations, which eventually can be extended by a direct product with a line or a space of constant curvature for yielding higher dimensional G\"{o}del universe. The considerations of $n$ rotations and also of constant curvature spaces is a new line of generalization and is being considered for the first time.Open AccessGeneralized Gödel universes in higher dimensions and pure Lovelock gravity
G\"{o}del universe is a homogeneous rotating dust with negative $\Lambda$ which is a direct product of three dimensional pure rotation metric with a line. We would generalize it to higher dimensions for Einstein and pure Lovelock gravity with only one $N$th order term. For higher dimensional generalization, we have to include more rotations in the metric, and hence we shall begin with the corresponding pure rotation odd $(d=2n+1)$-dimensional metric involving $n$ rotations, which eventually can be extended by a direct product with a line or a space of constant curvature for yielding higher dimensional G\"{o}del universe. The considerations of $n$ rotations and also of constant curvature spaces is a new line of generalization and is being considered for the first time. - Open Access
- 11 July 2016
- Published by Springer Nature in Journal of High Energy Physics
- Vol. 2016 (7) , 1-11
Dynamics of Carroll strings
- 11 July 2016
- Published by Springer Nature in Journal of High Energy Physics
- Vol. 2016 (7) , 1-11
Open AccessDynamics of Carroll strings