scholarly journals Linear stability of Einstein and de Sitter universes in the quadratic theory of modified gravity

2021 ◽  
Author(s):  
Mudhahir Al-Ajmi
Keyword(s):  
General Relativity ◽  
Linear Stability ◽  
Modified Gravity ◽  
De Sitter ◽  
Static Universe ◽  
Quadratic Theory ◽  
Sitter Universe ◽  
Einstein Static Universe ◽  
De Sitter Universe ◽  
Metric Perturbation

We consider the Einstein static and the de Sitter universe solutions and examine their instabilities in a subclass of quadratic modified theories for gravity. This modification proposed by Nash is an attempt to generalize general relativity. Interestingly, we discover that the Einstein static universe is unstable in the context of the modified gravity. In contrast to Einstein static universe, the de Sitter universe remains stable under metric perturbation up to the second order.

scholarly journals VANISHING COSMOLOGICAL CONSTANT IN MODIFIED GAUSS–BONNET GRAVITY WITH CONFORMAL ANOMALY

2007 ◽  
Vol 16 (05) ◽  
pp. 817-825 ◽  
Author(s):  
IVER BREVIK ◽  
JOHN QUIROGA
Keyword(s):  
General Relativity ◽  
Dark Energy ◽  
Cosmological Constant ◽  
Arbitrary Function ◽  
Modified Gravity ◽  
Quantum Effects ◽  
Conformal Anomaly ◽  
De Sitter ◽  
Sitter Universe ◽  
De Sitter Universe

We consider dark energy cosmology in a de Sitter universe filled with quantum conformal matter. Our model represents a Gauss–Bonnet model of gravity with contributions from quantum effects. To the General Relativity action an arbitrary function of the GB invariant, f(G), is added, and taking into account quantum effects from matter the cosmological constant is studied. For the considered model, the conditions for a vanishing cosmological constant are considered. Creation of a de Sitter universe by quantum effects in a GB modified gravity is discussed.

scholarly journals PHANTOM AND QUANTUM MATTER IN AN ANTI DE SITTER UNIVERSE

2004 ◽  
Vol 19 (01) ◽  
pp. 29-36 ◽  
Author(s):  
EMILIO ElIZALDE ◽  
JOHN QUIROGA HURTADO
Keyword(s):  
Perfect Fluid ◽  
Quantum Effects ◽  
Energy Conditions ◽  
De Sitter ◽  
Quantum Matter ◽  
Trace Anomaly ◽  
Sitter Universe ◽  
De Sitter Universe ◽  
Phantom Matter

We consider an anti de Sitter universe filled by quantum CFT with classical phantom matter and perfect fluid. The model represents the combination of a trace-anomaly annihilated and a phantom driven anti de Sitter universes. The influence exerted by the quantum effects and phantom matter on the AdS space is discussed. Different energy conditions in this type of universe are investigated and compared with those for the corresponding model in a de Sitter universe.

scholarly journals Scalar pair production in a magnetic field in de Sitter universe

2018 ◽  
Vol 78 (5) ◽  
Author(s):  
Mihaela-Andreea Băloi ◽  
Cosmin Crucean ◽  
Diana Popescu
Keyword(s):  
Magnetic Field ◽  
Pair Production ◽  
De Sitter ◽  
Sitter Universe ◽  
De Sitter Universe

scholarly journals Quantum annihilation of Anti-de Sitter universe

2000 ◽  
Vol 475 (3-4) ◽  
pp. 247-252 ◽  
Author(s):  
Iver Brevik ◽  
Sergei D. Odintsov
Keyword(s):  
De Sitter ◽  
Sitter Universe ◽  
De Sitter Universe

Coupling between time reversal and the space-time symmetries of the de Sitter universe

1974 ◽  
Vol 9 (10) ◽  
pp. 2710-2716 ◽  
Author(s):  
Ronald L. Mallett ◽  
Gordon N. Fleming
Keyword(s):  
Time Reversal ◽  
Space Time ◽  
De Sitter ◽  
Sitter Universe ◽  
De Sitter Universe

Massless particles, conformal group, and de Sitter universe

1981 ◽  
Vol 23 (6) ◽  
pp. 1278-1289 ◽  
Author(s):  
E. Angelopoulos ◽  
M. Flato ◽  
C. Fronsdal ◽  
D. Sternheimer
Keyword(s):  
Conformal Group ◽  
De Sitter ◽  
Massless Particles ◽  
Sitter Universe ◽  
De Sitter Universe
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