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Quantum mechanics rests on the assumption that time is a classical variable. As such, classical time is assumed to be measurable with infinite accuracy. However, all real clocks are subject to quantum fluctuations, which leads to the…

General Relativity and Quantum Cosmology · Physics 2008-11-26 J. M. Isidro , J. L. Gonzalez-Santander , P. Fernandez de Cordoba

The understanding of time and dynamics can be elucidated by examining the concept of entanglement in quantum theory. This particular perspective on time is referred to as the timeless approach, which posits that the universe exists in a…

General Relativity and Quantum Cosmology · Physics 2023-12-07 H. Hadi , F. Darabi , K. Atazadeh

A cosmological time variable is emerged from the Hamiltonian formulation of Friedmann model to measure the evolution of dynamical observables in the theory. A set of observables has been identified for the theory on the null hypersurfaces…

General Relativity and Quantum Cosmology · Physics 2008-11-26 Hossein Farajollahi

In canonical quantum cosmology, the wave function of the universe lacks explicit time dependence. However, time evolution may be present implicitly through the semiclassical superspace variables, which themselves depend on time in classical…

High Energy Physics - Theory · Physics 2015-06-17 Audrey T. Mithani , Alexander Vilenkin

A new dynamical paradigm merging quantum dynamics with cosmology is discussed. Time evolution involves a genuine passage of time, which distinguishes the formalism from those where dynamics in space is equivalent to statics in space-time.…

General Physics · Physics 2024-02-01 Marek Czachor

We use the quantum unimodular theory of gravity to relate the value of the cosmological constant, $\Lambda$, and the energy scale for the emergence of cosmological classicality. The fact that $\Lambda$ and unimodular time are complementary…

High Energy Physics - Theory · Physics 2023-01-04 Niayesh Afshordi , João Magueijo

We argue that in classical and quantum theories of gravity the configuration space and Hilbert space may not be constructible through any finite procedure. If this is the case then the "problem of time" in quantum cosmology may be a…

General Relativity and Quantum Cosmology · Physics 2007-05-23 Stuart Kauffman , Lee Smolin

In light of G\"{o}del's undecidability results (incomplete theorems) for math, quantum indeterminism indicates that physics and the Universe may be indeterministic, incomplete, and open in nature, and therefore demand no single unification…

General Physics · Physics 2020-03-11 Wanpeng Tan

Universe structure emerges in the unreduced, complex-dynamical interaction process with the simplest initial configuration (two attracting homogeneous fields). The unreduced interaction analysis avoiding any perturbative model gives…

General Physics · Physics 2015-03-20 Andrei P. Kirilyuk

The origin and nature of time in complex systems is explored using quantum (or 'Feynman') clocks and the signals produced by them. Networks of these clocks provide the basis for the evolution of complex systems. The general concept of…

General Relativity and Quantum Cosmology · Physics 2007-05-23 Scott Hitchcock

We describe a link between the cosmological constant problem and the problem of time in quantum gravity. This arises by examining the relationship between the cosmological constant and vacuum energy in light of non-perturbative formulations…

General Relativity and Quantum Cosmology · Physics 2010-03-12 Viqar Husain

It is postulated there is not a precise static instant in time underlying a dynamical physical process at which the relative position of a body in relative motion or a specific physical magnitude would theoretically be precisely determined.…

General Physics · Physics 2007-05-23 Peter Lynds

Time has always played a crucial role in cosmology. I review some of the aspects of the present cosmological model which are more directly related to time, such as: the definition of a cosmic time; the existence of typical timescales and…

History and Philosophy of Physics · Physics 2017-03-22 A. Balbi

Noncommutative spacetimes are widely believed to model some properties of the quantum structure of spacetime at the Planck regime. In this contribution the construction of (anti-)de Sitter noncommutative spacetimes obtained through quantum…

High Energy Physics - Theory · Physics 2017-08-22 A. Ballesteros , I. Gutiérrez-Sagredo , F. J. Herranz , C. Meusburger , P. Naranjo

From the principles of quantum cosmologies we can justify the reason for an inverse-square law for the cosmological constant with no conflict with observations. Although this general expression for $\Lambda$ is well known in the literature,…

General Relativity and Quantum Cosmology · Physics 2008-03-19 E. M. C. Abreu , C. M. L. dos Reis

Quantum cosmology is the quantum theory of the entire universe. Although strange at first sight, it is appropriate because (1) our world appears to be fundamentally quantum, (2) the classical description of gravity breaks down at…

General Relativity and Quantum Cosmology · Physics 2007-05-23 Don N. Page

We present an extension of general relativity in which the cosmological constant becomes dynamical and turns out to be conjugate to the Chern-Simons invariant of the Ashtekar connection on a spatial slicing. The latter has been proposed in…

General Relativity and Quantum Cosmology · Physics 2018-07-24 Stephon Alexander , Joao Magueijo , Lee Smolin

Quantum mechanics in its presently known formulation requires an external classical time for its description. A classical spacetime manifold and a classical spacetime metric are produced by classical matter fields. In the absence of such…

General Relativity and Quantum Cosmology · Physics 2008-11-26 T. P. Singh

The evolution of the wave function in quantum mechanics is deterministic like that of classical waves. Only when we bring in observers the fundamentally different quantum reality emerges. Similarly the introduction of observers changes the…

General Physics · Physics 2020-10-16 Jan O. Stenflo

The exact solution of the Hamiltonian constraint in canonical gravity and the resultant reduction of Einstein's theory reveal the synergy between gravitation and the intrinsic cosmic clock of our expanding universe. Intrinsic Time…

General Relativity and Quantum Cosmology · Physics 2023-11-27 Chopin Soo