# Adam BalcerzakUniversity of Szczecin · Institute of Physics

Adam Balcerzak

PhD

## About

35

Publications

2,582

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361

Citations

Introduction

**Skills and Expertise**

Additional affiliations

October 2005 - present

## Publications

Publications (35)

We consider spherically symmetric inhomogeneous Stephani universes, the
center of symmetry being our location. We emphasize that in these models
comoving observers do not follow geodesics, in particular comoving perfect
fluids have necessarily a radial dependent pressure. We consider a subclass of
these models characterized by some inhomogeneity pa...

Exact luminosity distance and apparent magnitude formulas are applied to
Union2 557 supernovae sample in order to constrain possible position of an
observer outside of the center of symmetry in spherically symmetric
inhomogeneous pressure Stephani universes which are complementary to
inhomogeneous density Lema\^itre-Tolman-Bondi (LTB) void models....

We derive a redshift drift formula for the spherically symmetric
inhomogeneous pressure Stephani universes which are complementary to the
spherically symmetric inhomogeneous density Lema\^itre-Tolman-Bondi models. We
show that there is a clear difference between redshift drift predictions for
these two models as well as between the Stephani models...

By setting some special boundary conditions in the variational principle we
obtain junction conditions for the five-dimensional $f(R)$ gravity which in the
Einstein limit $f(R)\rightarrow R$ transform into the standard Randall-Sundrum
junction conditions. We apply these junction conditions to a particular model
of a Friedmann universe on the brane...

We derive the most general junction conditions for the fourth-order brane gravity constructed of arbitrary functions of curvature invariants. We reduce these fourth-order theories to second order theories at the expense of introducing new scalar and tensor fields - the scalaron and the tensoron. In order to obtain junction conditions we apply the m...

In this paper, we consider a high-curvature limit of the varying fundamental constants toy model in which both the value of the speed of light and the value of the gravitational constant are related to the values of the two non-minimally coupled scalar fields. The high-curvature limit motivates the application of the third quantization procedure to...

Using the third quantization formalism we study the quantum entanglement of universes created in pairs within the framework of standard homogeneous and isotropic cosmology. In particular, we investigate entanglement quantities (entropy, temperature) around the maxima, minima and inflection points of the classical evolution. The novelty from previou...

Using the 3rd quantization formalism we study the quantum entanglement of universes created in pairs within the framework of standard homogeneous and isotropic cosmology. In particular, we investigate entanglement quantities (entropy, temperature) around maxima, minima and inflection points of the classical evolution. The novelty from previous work...

In this paper we consider a third quantized cosmological model with varying speed of light c and varying gravitational constant G both represented by non-minimally coupled scalar fields. The third quantization of such a model leads to a scenario of the doubleverse with the two components being quantum mechanically entangled. We calculate the two pa...

In this paper we consider a third quantized cosmological model with varying speed of light $c$ and varying gravitational constant $G$ both represented by non-minimally coupled scalar fields. The third quantization of such a model leads to a scenario of the doubleverse with the two components being quantum mechanically entangled. We calculate the tw...

Although the standard cosmological model explains most of the observed phenomena it still struggles with the problem of initial singularity. An interesting scenario in which the problem of the initial singularity is somehow circumvented was proposed in the context of string theory where the canonical quantisation procedure was additionally applied...

Although the standard cosmological model explains most of the observed phenomena it still struggles with the problem of initial singularity. An interesting scenario in which the problem of the initial singularity is somehow circumvented was proposed in the context of string theory where the canonical quantisation procedure was additionally applied....

In this paper we consider a specific type of the bimetric theory of gravitation with the two different metrics introduced in the cosmological frame. Both metrics respect all the symmetries of the standard FLRW solution and contain conformally related spatial parts. One of the metric is assumed to describe the causal structure for the matter. Anothe...

In this paper we consider a specific type of the bimetric theory of gravitation with the two different metrics introduced in the cosmological frame. Both metrics respect all the symmetries of the standard FLRW solution and contain conformally related spatial parts. One of the metric is assumed to describe the causal structure for the matter. Anothe...

We study scenarios of parallel cyclic multiverses which allow for a different evolution of the physical constants, while having the same geometry. These universes are classically disconnected, but quantum-mechanically entangled. Applying the thermodynamics of entanglement, we calculate the temperature and the entropy of entanglement. It emerges tha...

In this paper we extend a new method to measure possible variation of the speed of light by using Baryon Acoustic Oscillations and the Hubble function presented in our earlier paper [V. Salzano, M. P. D\c{a}browski, and R. Lazkoz, Phys. Rev. D93, 063521 (2016)] onto an inhomogeneous model of the universe. The method relies on the fact that there is...

We present basic ideas of the varying speed of light cosmology, its formulation, benefits and problems. We relate it to the theories of varying fine structure constants and discuss some new tests (redshift drift and angular diameter distance maximum) which may allow measuring timely and spatial change of the speed of light by using the future missi...

Using the idea of regularisation of singularities due to the variability of the fundamental constants in cosmology we study
the cyclic universe models. We find two models of oscillating and non-singular mass density and pressure (”non-singular” bounce)
regularised by varying gravitational constant G despite the scale factor evolution is oscillating...

We consider gravity theory with varying speed of light and varying
gravitational constant. Both constants are represented by non-minimally coupled
scalar fields. We examine the cosmological evolution in the near curvature
singularity regime. We find that at the curvature singularity the speed of
light goes to infinity while the gravitational consta...

We discuss minisuperspace models within the framework of varying physical
constants theories including $\Lambda$-term. In particular, we consider the
varying speed of light (VSL) theory and varying gravitational constant theory
(VG) using the specific ans\"atze for the variability of constants: $c(a) = c_0
a^n$ and $G(a)=G_0 a^q$. We find that most...

We derive a luminosity distance formula for the varying speed of light (VSL)
theory which involves higher order characteristics of expansion such as jerk,
snap and lerk which can test the impact of varying $c$ onto the evolution of
the universe. We show that the effect of varying $c$ is possible to be isolated
due to the relations connecting observ...

We derive a redshift drift formula within the framework of varying speed of
light (VSL) theory using the specific ansatz for the variability of $c(t) = c_0
a^n(t)$. We show that negative values of the parameter $n$, which correspond to
diminishing value of the speed of light during the evolution of the universe,
effectively rescales dust matter to...

We derive a redshift drift formula within the framework of varying speed of
light (VSL) theory using the specific ansatz for the variability of $c(t) = c_0
a^n(t)$. We show that negative values of the parameter $n$, which corresponds
to diminishing value of the speed of light during the evolution of the
universe, effectively rescales dust matter to...

We review the variety of new singularities in homogeneous and isotropic FRW
cosmology which differ from standard Big-Bang and Big-Crunch singularities and
suggest how the nature of these singularities can be influenced by the varying
fundamental constants.

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We derive the redshift drift formula for the spherically symmetric
Stephani cosmological models. We show that in the considered class of
the Stephani models with a centrally placed observer the redshift drift
exhibits the behavior similar to the behavior of the redshift drift in
the void LTB cosmological models at high redshifts. However, unlike in...

We discuss evolution of density perturbations in cosmological models which
admit finite scale factor singularities. After solving the matter perturbations
equations we find that there exists a set of the parameters which admit a
finite scale factor singularity in future and instantaneously recover matter
density evolution history which are indistin...

We discuss a general fourth-order theory of gravity and formulate the generalized Israel junction conditions for the theory by application of a generalized Gibbons-Hawking boundary term which is added to the action of the fourth-order gravity theory. Next, we use the generalized Israel junction condition for the construction of a higher-order gravi...

We discuss a general fourth‐order theory of gravity and formulate the generalized Israel junction conditions for the theory by application of a generalized Gibbons‐Hawking boundary term which is added to the action of the fourth‐order gravity theory. Next, we use the generalized Israel junction condition for the construction of a higher‐order gravi...

By the application of the generalized Israel junction conditions we derive cosmological equations for the fourth-order $f(R)$ brane gravity and study their cosmological solutions. We show that there exists a non-static solution which describes a four-dimensional de-Sitter $(dS_4)$ brane embedded in a five-dimensional anti-de-Sitter $(AdS_5)$ bulk f...

We discuss a very general theory of gravity, of which Lagrangian is an arbitrary function of the curvature invariants, on the brane. In general, the formulation of the junction conditions (except for Euler characteristics such as Gauss-Bonnet term) leads to the powers of the delta function and requires regularization. We suggest the way to avoid su...

We discuss a general fourth-order theory of gravity on the brane. In general, the formulation of the junction conditions (except for Euler characteristics such as Gauss-Bonnet term) leads to the higher powers of the delta function and requires regularization. We suggest the way to avoid such a problem by imposing the metric and its first derivative...

We discuss exotic singularities in the evolution of the universe motivated by the progress of observations in cosmology. Among them there are: Big-Rip (BR), Sudden Future Singularities (SFS), Generalized Sudden Future Singularities (GSFS), Finite Density Singularities (FD), type III, and type IV singularities. We relate some of these singularities...

We discuss the behaviour of strings propagating in spacetimes which allow future singularities of either a sudden future or a Big-Rip type. We show that in general the invariant string size remains finite at sudden future singularities while it grows to infinity at a Big-Rip. This claim is based on the discussion of both the tensile and null string...

## Projects

Project (1)

The project contains the problems related to the theoretical and observational consequences of timely and spatial variability of the speed of light c, gravitational constant G, fine structure constant α, proton to electron mass ratio and other physical constants. The scenarios of the evolution of the Universe with varying fundamental constants in the context of superstring theory (superstring landscape) and the Multiverse concept are also considered.