Related papers: Challenges for String Cosmology
We review the observational and theoretical constraints on extragalactic magnetic fields across cosmic environment. In the next decade, the combination of sophisticated numerical simulations and various observational probes might succeed in…
We review aspects of spacetime singularities from the view point of string theory. Examples considered include cosmological, cosmic string and black-hole singularities. We also discuss the consistency of viewing black-holes as excited…
These four lectures, addressed to an audience of graduate students in experimental high energy physics, survey some of the basic concepts in string theory. The purpose is to convey a general sense of what string theory is and what it has…
We note that in general there exist two basic aspects in any branch of physics, including cosmology - one dealing with the attributes of basic constituents and forces of nature, the other dealing with how structures arise from them and how…
Cosmology contributes a good deal to the investigation of variation of fundamental physical constants. High resolution data is available and allows for detailed analysis over cosmological distances and a multitude of methods were developed.…
In what has become a standard eternal inflation picture of the string landscape there are many problematic consequences and a difficulty defining probabilities for the occurrence of each type of universe. One feature in particular that…
In an effort to promote communication between the formal and phenomenological branches of the high-energy theory community, we provide a description of some important issues in supersymmetric and string phenomenology. We describe each…
String theory contains sources like orientifold planes that support higher derivative interactions. These interactions make possible static flux compactifications which are forbidden in supergravity. They can also lead to violations of the…
This thesis is dedicated to the study of inflationary scenarios based on string theory. Inflation is a brief period of accelerated expansion in the very early Universe which gives natural explanations for problems of the Standard Big Bang…
Assuming string theorists will not soon provide a compelling case for the primary theory underlying particle physics, the field will proceed as it has historically: with data stimulating and testing ideas. Ideally the soft supersymmetry…
Various contributions to the cosmological constant are discussed and confronted with its recent measurement. We briefly review different scenarious -- and their difficulties -- for a solution of the cosmological constant problem.
Talk given at the ``4th Hellenic School on Elementary Particle Physics", Corfu, 2-20 September 1992: The propagation of strings in cosmological space-time backgrounds is reviewed. We show the relation of a special class of cosmological…
We demonstrate that string consistency in four spacetime dimensions leads to a spectrum of string states which satisfies the supertrace constraints Str(M^0)=0 and Str(M^2)=\Lambda at tree level, where \Lambda is the one-loop string…
I review the present theoretical attempts to understand the quantum properties of spacetime. In particular, I illustrate the main achievements and the main difficulties in: string theory, loop quantum gravity, discrete quantum gravity…
We consider the propagation of classical and quantum strings on cosmological space-times which interpolate from a collapsing phase to an expanding phase. We begin by considering the classical propagation of strings on space-times with…
Assuming that superstring theory is the fundamental theory which unifies all forces of Nature at the quantum level, I argue that there are key limitations on the applicability of effective field theory techniques in describing early…
We give a brief summary of present bounds on the size of possible extra-dimensions as well as the string scale from collider experiments.
We describe the detailed study and results of high-resolution numerical simulations of string-induced structure formation in open universes and those with a non-zero cosmological constant. The effect from small loops generated from the…
This article, based on the Klein lecture, contains some new results and new speculations on various topics. They include discussion of open strings in the AdS space, unusual features of D-branes, conformal gauge theories in higher…
Stringy cosmology displays features that are different from standard cosmology. One may be surprised in that in this scenario there is no phase transition between the radiation dominated phase and matter dominated phase and the universe is…