Jbis Journal of the British Interplanetary Society, 1991
Le principe anthropique suggere que certaines caracteristiques de l'Univers sont determinees ... more Le principe anthropique suggere que certaines caracteristiques de l'Univers sont determinees par la necessite de l'emergence de la vie. Les preuves reposent dans un nombre de coincidences impliquant les constantes de la physique et diverses quantites cosmologiques qui seraient autrement inexpliquees. Ces coincidences sont passees en revue et l'etendue sur laquelle elles soutiennent les differentes versions du principe anthropique est discutee
In this chapter we describe models with low scale quantum gravity. While clearly speculative, the... more In this chapter we describe models with low scale quantum gravity. While clearly speculative, these models have been very useful in demonstrating that we do not know from first principles the energy scale at which quantum gravitational effects become large. We emphasize that it is thus important to search for quantum gravitational effects, including the formation of small black holes in experiments such as the Large Hadron Collider and cosmic ray experiments.
Recent developments in cosmology and particle physics, such as the string landscape picture, have... more Recent developments in cosmology and particle physics, such as the string landscape picture, have led to the remarkable realization that our universe - rather than being unique - could be just one of many universes. The multiverse proposal helps to explain the origin of the universe and some of its observational features. Since the physical constants can be different in other universes, the fine-tunings which appear necessary for the emergence of life may also be explained. Nevertheless, many physicists remain uncomfortable with the multiverse proposal, since it is highly speculative and perhaps untestable. In this volume, a number of active and eminent researchers in the field - mainly cosmologists and particle physicists but also some philosophers - address these issues and describe recent developments. The articles represent the full spectrum of views, providing for the first time an overview of the subject. They are written at different academic levels, engaging lay-readers and ...
... effect on the dynamics of the early universe (in general rendering it highly anisotropic) eve... more ... effect on the dynamics of the early universe (in general rendering it highly anisotropic) even if ~g ... An important role is played by the ratio of the duration of each burst to the ... a planet with orbital period P responds to the component of the gravitational wave spectrum with frequency ...
A new family of spherically symmetric similarity solutions which represent inhomogeneous perturba... more A new family of spherically symmetric similarity solutions which represent inhomogeneous perturbations of the Kantowski-Sachs model is discussed. The present solutions are more general than the similarity solutions found by Wesson (1986) and Ponce de Leon (1988), in that the azimuthal as well as the radial metric component is allowed to depend on the similarity variable. It is demonstrated that
... Printed in USA THE PRIMORDIAL BLACK HOLE MASS SPECTRUM* BERNARD J. CARR Department of Applied... more ... Printed in USA THE PRIMORDIAL BLACK HOLE MASS SPECTRUM* BERNARD J. CARR Department of Applied Mathematics and Theoretical Physics, Cambridge University, Cambridge, England; and California Institute of Technology, Pasadena Received 1975 January 31 ...
We examine the possible cosmological consequences of Population III stars. Their dark remnants co... more We examine the possible cosmological consequences of Population III stars. Their dark remnants could provide the ''missing mass.'' Their light could have produced either the entire 3 K background or observable distortions in its spectrum. Their heat or explosions could have reionized the universe and perhaps produced galaxies. Their helium yield could suffice to provide an alternative explanation for the
Abstract Many of the baryons in the Universe are dark and at least some of the dark baryons could... more Abstract Many of the baryons in the Universe are dark and at least some of the dark baryons could be in the form of compact objects. Such objects could be in various locations – galactic discs, galactic halos, clusters of galaxies or intergalactic space – and each of these is associated with a dark matter problem. For each site we consider the various dynamical constraints which can be placed on the fraction of the dark matter in compact objects of different mass. We also apply these limits to the situation in which the compact objects are clusters of smaller objects.
The constraints on the number of evaporating primordial black holes imposed by observations of th... more The constraints on the number of evaporating primordial black holes imposed by observations of the cosmological gamma-ray background do not exclude their making a significant contribution to the Galactic flux of cosmic ray photons, electrons, positrons and ...
Observations suggest that the mass density of the Universe is dominated, not by ordinary matter, ... more Observations suggest that the mass density of the Universe is dominated, not by ordinary matter, but by exotic particles which are a relic of the Big Bang. In this case, a new dimensionless cosmological ratio arises, the ratio of the mass density in ordinary matter to that in exotic matter, whose value is about 0.1. A priori, it might seem remarkable that this ratio should be so close to unity. However, we point out that, for many exotic dark matter candidates, the ratio is related to the fundamental scales of particle physics. A value of order unity arises naturally provided rather simple relationships exist between these scales. If the exotic particles are of a kind whose relic abundance is determined by annihilations (e.g., the photino or a heavy neutrino), then the required relationship is already satisfied for independent, cosmological reasons.
The notion that certain features of the universe, such as the values of the physical constants, m... more The notion that certain features of the universe, such as the values of the physical constants, may be constrained by the requirement that intelligent observers can arise was first mooted nearly 40 years ago. This "anthropic principle" has been a focus of controversy (even intense antipathy in some quarters) ever since. However, judging by a conference that took place in Cambridge at the end of August, the notion seems to be attracting the interest of an increasing number of eminent physicists. The meeting–the first in a series supported in part by the Templeton Foundation–took place at the Cambridge home of Martin Rees, one of the foremost advocates of the anthropic principle. Future meetings will address the biological and philosophical aspects of the subject.
Jbis Journal of the British Interplanetary Society, 1991
Le principe anthropique suggere que certaines caracteristiques de l'Univers sont determinees ... more Le principe anthropique suggere que certaines caracteristiques de l'Univers sont determinees par la necessite de l'emergence de la vie. Les preuves reposent dans un nombre de coincidences impliquant les constantes de la physique et diverses quantites cosmologiques qui seraient autrement inexpliquees. Ces coincidences sont passees en revue et l'etendue sur laquelle elles soutiennent les differentes versions du principe anthropique est discutee
In this chapter we describe models with low scale quantum gravity. While clearly speculative, the... more In this chapter we describe models with low scale quantum gravity. While clearly speculative, these models have been very useful in demonstrating that we do not know from first principles the energy scale at which quantum gravitational effects become large. We emphasize that it is thus important to search for quantum gravitational effects, including the formation of small black holes in experiments such as the Large Hadron Collider and cosmic ray experiments.
Recent developments in cosmology and particle physics, such as the string landscape picture, have... more Recent developments in cosmology and particle physics, such as the string landscape picture, have led to the remarkable realization that our universe - rather than being unique - could be just one of many universes. The multiverse proposal helps to explain the origin of the universe and some of its observational features. Since the physical constants can be different in other universes, the fine-tunings which appear necessary for the emergence of life may also be explained. Nevertheless, many physicists remain uncomfortable with the multiverse proposal, since it is highly speculative and perhaps untestable. In this volume, a number of active and eminent researchers in the field - mainly cosmologists and particle physicists but also some philosophers - address these issues and describe recent developments. The articles represent the full spectrum of views, providing for the first time an overview of the subject. They are written at different academic levels, engaging lay-readers and ...
... effect on the dynamics of the early universe (in general rendering it highly anisotropic) eve... more ... effect on the dynamics of the early universe (in general rendering it highly anisotropic) even if ~g ... An important role is played by the ratio of the duration of each burst to the ... a planet with orbital period P responds to the component of the gravitational wave spectrum with frequency ...
A new family of spherically symmetric similarity solutions which represent inhomogeneous perturba... more A new family of spherically symmetric similarity solutions which represent inhomogeneous perturbations of the Kantowski-Sachs model is discussed. The present solutions are more general than the similarity solutions found by Wesson (1986) and Ponce de Leon (1988), in that the azimuthal as well as the radial metric component is allowed to depend on the similarity variable. It is demonstrated that
... Printed in USA THE PRIMORDIAL BLACK HOLE MASS SPECTRUM* BERNARD J. CARR Department of Applied... more ... Printed in USA THE PRIMORDIAL BLACK HOLE MASS SPECTRUM* BERNARD J. CARR Department of Applied Mathematics and Theoretical Physics, Cambridge University, Cambridge, England; and California Institute of Technology, Pasadena Received 1975 January 31 ...
We examine the possible cosmological consequences of Population III stars. Their dark remnants co... more We examine the possible cosmological consequences of Population III stars. Their dark remnants could provide the ''missing mass.'' Their light could have produced either the entire 3 K background or observable distortions in its spectrum. Their heat or explosions could have reionized the universe and perhaps produced galaxies. Their helium yield could suffice to provide an alternative explanation for the
Abstract Many of the baryons in the Universe are dark and at least some of the dark baryons could... more Abstract Many of the baryons in the Universe are dark and at least some of the dark baryons could be in the form of compact objects. Such objects could be in various locations – galactic discs, galactic halos, clusters of galaxies or intergalactic space – and each of these is associated with a dark matter problem. For each site we consider the various dynamical constraints which can be placed on the fraction of the dark matter in compact objects of different mass. We also apply these limits to the situation in which the compact objects are clusters of smaller objects.
The constraints on the number of evaporating primordial black holes imposed by observations of th... more The constraints on the number of evaporating primordial black holes imposed by observations of the cosmological gamma-ray background do not exclude their making a significant contribution to the Galactic flux of cosmic ray photons, electrons, positrons and ...
Observations suggest that the mass density of the Universe is dominated, not by ordinary matter, ... more Observations suggest that the mass density of the Universe is dominated, not by ordinary matter, but by exotic particles which are a relic of the Big Bang. In this case, a new dimensionless cosmological ratio arises, the ratio of the mass density in ordinary matter to that in exotic matter, whose value is about 0.1. A priori, it might seem remarkable that this ratio should be so close to unity. However, we point out that, for many exotic dark matter candidates, the ratio is related to the fundamental scales of particle physics. A value of order unity arises naturally provided rather simple relationships exist between these scales. If the exotic particles are of a kind whose relic abundance is determined by annihilations (e.g., the photino or a heavy neutrino), then the required relationship is already satisfied for independent, cosmological reasons.
The notion that certain features of the universe, such as the values of the physical constants, m... more The notion that certain features of the universe, such as the values of the physical constants, may be constrained by the requirement that intelligent observers can arise was first mooted nearly 40 years ago. This "anthropic principle" has been a focus of controversy (even intense antipathy in some quarters) ever since. However, judging by a conference that took place in Cambridge at the end of August, the notion seems to be attracting the interest of an increasing number of eminent physicists. The meeting–the first in a series supported in part by the Templeton Foundation–took place at the Cambridge home of Martin Rees, one of the foremost advocates of the anthropic principle. Future meetings will address the biological and philosophical aspects of the subject.
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Papers by Bernard Carr