arXiv subjects

Edward Tetteh-Lartey

Publications and source records attributed to Edward Tetteh-Lartey.

3 recordsLinked to original sources

arXiv2007

Toward a Quantum theory of Gravity and a Resolution of the Time paradox

One of the major issues confronting theoretical physics is finding a quantum theory of gravity and a resolution to the cosmological constant problem. It is believed that a true quantum theory of gravity will lead to a solution to the this problem. Finding a quantum theory of gravity has been a difficult issue mainly because of the high energy scale required for testing quantum gravity which is far the reach of current accelerators. Also general relativity does not possess a natural time variable thus the nature of time is not clear in quantum gravity, a problem called the time paradox. The two main approaches are string theory and loop quantum gravity. String theory unifies all interaction but provides a perturbative background dependent formulation which violates general covariance. Loop quantum gravity provides a non-perturbative approach but does not provide a unified theory of interactions, which most physicist believe should be the case at Planck scale energies. It doesn't also seem to connect with low energy phenomena. In this note I look at how quantum cosmology provides useful inference toward a quantum gravity theory by merging inputs from the perturbative and the non-perturbative approaches, and resolving the time paradox issue.

hep-th↗

arXiv2007

Vacuum Selection on the String Landscape

I examine some non-anthropic approaches to the string landscape. These approaches are based on finding the initial conditions of the universe using the wavefunction of the multiverse to select the most probable vacuum out of this landscape. All approaches tackled so far seems to have their own problems and there is no clear cut alternative to anthropic reasoning. I suggest that finding the initial conditions may be irrelevant since all possible vacua on the landscape are possible initial state conditions and eternal inflation could generate all the other vacua. We are now left to reason out why we are observing the small value of the cosmological constant (CC). I address this issue in the contest of noncritical string theory in which all values of the cosmological constant on the landscape are departures from critical equilibrium state.

hep-th↗

arXiv2006

Unification, the Big Bang, and the Cosmological Constant

The two major goals in fundamental physics are: 1) Unification of all forces incorporating relativity and quantum theory, 2) Understanding the origin and evolution of the Universe as well as explaining the smallness of the cosmological constant. Several efforts have been made in the last few decades towards achieving these goals with some successes and failures. The current best theory we have for unification of all forces is Superstring/M Theory. However current evidence suggests our Universe is flat and accelerating. A Universe with a positive cosmological constant will have serious implications for string theory since the S-Matrix cannot be well defined and Superstring/M Theory is only formulated in flat Minkowski background. Holographic principle provides a way out as shown by the AdS/CFT and dS/CFT correspondence, but it remains to be proved if it is valid for our non-conformal, non-supersymmetric Universe. Aside from the issue of defining M-Theory in a de Sitter background, why the cosmological constant is so small remains puzzling and needs to be understood. The ``cosmological constant problem'' has brought physics to a standstill towards any major development and remains currently the most disturbing issue. Conventional big bang cosmology has not yet produced a satisfactory explanation of the small value of the cosmological constant. An attempt by SuperString/M Theory in this direction is given by the Ekpyrotic/Cyclic model. The aim of this review is not to introduce any new concepts not already known, but give an overview of current state of affairs in high energy physics, highlighting some successes and failures and making some few suggestions on areas to focus to resolve some of these outstanding issues.

physics.pop-ph↗