Some Topics On Dark Energy

The discovery of dark energy imposes a great challenge to the modern the-ory of physics. It is believed that study on this problem might bring about abreakthrough to the development of basic theory. With latest astronomical ob-servations, as well as the WMAP's high-precision exploration of anisotropy ofCMB, human beings have entered into an era of precise cosmology. Both darkenergy and cosmology have become hot issues in the research on the frontier ofscience worldwide. In fact, research on these areas represents people's consistentpursuit of truth in the nature.The current study explores some problems relevantto accelerating expansion of our universe and dark energy.The entire dissertation is divided into five chapters. Chapter One serves asthe Introduction. It refers to some fundamental facts about cosmology, includingits three basic elements, cosmological principle, and the latest outcome in as-tronomical observations. Besides, it tells the fundamental theories of cosmologybased on the general theory of relativity, and gives a brief account of FriedmannEquation and various models of dark energy.Chapter Two dwells on the work done by us, includingPhantom cosmologywith non-minimally coupled real scalar field, Dark Energy Cosmology with SpinorField, and Dark Energy Cosmology with a Rarita-Schwinger Field. In this part,the conditions on which they can play the role of dark energy and Phantom aregiven. Also, the model's stability is discussed.Chapter Three discusses Holographic Dark Energy in Induced Gravity. Itis discovered that the choice of Hubble scale or particle horizon as the IR cutoffcan not give an accelerating expansion. Only by taking the event horizon asthe IR cutoff, can we get the accelerating expansion of our universe.In Chapter Four, we discuss black hole area quantization under the conditionof dark energy. Most of the previous discussions on black hole thermodynamicshave not paid enough attention to the influence of dark energy, whereas the actualuniverses is dominated by it. Therefore, it is worthwhile to consider the influence of dark energy upon black hole thermodynamics. Our research indicates that thearea spectrum of a black surrounded by Quintessence is the same as the spectrumwithout considering dark energy. The role which dark energy plays is reflectedmainly in its influence on the radius of the black hole event horizon. For thisreason, all the previous researches on black hole thermodynamics, even if theyhave been carried out without considering dark energy, are still very enlightening.Chapter Five is both a conclusion and a prospect. It sums up the entiredissertation, and looks into the future work.