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, 1983 Space and time are the most fundamental ideas of the scientist’s picture of the world, and also of the language in which we all describe our thoughts and sensations. We use the concepts of space and time to “relate” ourselves to world phenomena that we and other people observe and to “verify” that what other people report to us as “their observations ...
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Physical Review D, 1985
The usual proof of the CPT theorem does not apply to theories which include the gravitational field. Nevertheless, it is shown that CPT invariance still holds in these cases provided that, as has recently been proposed, the quantum state of the Universe is defined by a path integral over metrics that are compact without boundary. The observed asymmetry
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The usual proof of the CPT theorem does not apply to theories which include the gravitational field. Nevertheless, it is shown that CPT invariance still holds in these cases provided that, as has recently been proposed, the quantum state of the Universe is defined by a path integral over metrics that are compact without boundary. The observed asymmetry
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On the cosmological arrow of time
2023The cosmological arrow of time is defined by the initial conditions of the Universe and its subsequent expansion. Wetterich [1] has proposed an alternative picture of the expanding Universe where the observed cosmological redshift can equivalently be viewed as originating from the increase in mass of particles over time. In this article, we address the
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The Physics Teacher, 1967
This article is taken from an introductory textbook by the author, scheduled for publication early in 1968; it represents the concluding section of a chapter on entropy and the second law of thermodynamics. It attempts to draw together the microscopic and macroscopic threads of physics as applied to the concept of time.
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This article is taken from an introductory textbook by the author, scheduled for publication early in 1968; it represents the concluding section of a chapter on entropy and the second law of thermodynamics. It attempts to draw together the microscopic and macroscopic threads of physics as applied to the concept of time.
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Physics Bulletin, 1971
I would like to comment on the recent article by Dr P C W Davies (April 1971 p211), in which the author discusses the direction of time's arrow. The concept of direction implies a reference frame relative to which direction can be determined.
D F A Edwards, P C W Davies, A H Nelson
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I would like to comment on the recent article by Dr P C W Davies (April 1971 p211), in which the author discusses the direction of time's arrow. The concept of direction implies a reference frame relative to which direction can be determined.
D F A Edwards, P C W Davies, A H Nelson
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, 1995 I begin by stating that time is real. To do otherwise (as some famous philosophers from the past have implied) would be ‘philosophical extravagance’[6]. As Shallis [24] put it: ‘The fundamental perception of all mankind is the distinction between day and night, of the phases of the moon and the passage of the planets through the realm of the fixed ...
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The Thermodynamical Arrow of Time
1989The thermodynamical arrow of time is characterized by an increase of entropy according to the Second Law, which was postulated by Clausius in 1865 on the basis of Carnot’s process. It can be written in the form (see also (3.1’) on page 57) $$\begin{array}{*{20}{c}} {\frac{{dS}}{{dt}} = {{{\left\{ {\frac{{dS}}{{dt}}} \right\}}}_{{ext}}} + {{{\left\{
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1989
After a stone has been dropped into a pond, one observes concentrically diverging (‘defocussing’) waves. Similarly, after an electric current has been switched on, one finds a retarded electromagnetic field that is moving away from its source. Since the fundamental laws of nature, which describe these phenomena, are invariant under time-reversal, they ...
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After a stone has been dropped into a pond, one observes concentrically diverging (‘defocussing’) waves. Similarly, after an electric current has been switched on, one finds a retarded electromagnetic field that is moving away from its source. Since the fundamental laws of nature, which describe these phenomena, are invariant under time-reversal, they ...
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2018
Much has been said, conjectured, speculated and dreamed about the origin and evolution of the universe, by scientists and non-scientists alike. Any system of thought claiming to provide an understanding of the physical world, made some statement about the origin and evolution of the universe.
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Much has been said, conjectured, speculated and dreamed about the origin and evolution of the universe, by scientists and non-scientists alike. Any system of thought claiming to provide an understanding of the physical world, made some statement about the origin and evolution of the universe.
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American Journal of Physics, 1962
The time symmetry of the physical laws is discussed. The asymmetry in all statistical processes is found to be related to the tendency for radiation to diverge and that in turn is related to the expansion of the universe. No asymmetry is contained in the laws of electrodynamics, and the choice of the retarded potentials is not a time unsymmetrical step.
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The time symmetry of the physical laws is discussed. The asymmetry in all statistical processes is found to be related to the tendency for radiation to diverge and that in turn is related to the expansion of the universe. No asymmetry is contained in the laws of electrodynamics, and the choice of the retarded potentials is not a time unsymmetrical step.
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