Property Of Pseudo Rip

This paper will explain the basic knowledge of cosmology first. The universe is the largest material in the world, human beings began to explore the universe soon after their born. Cosmology is a subject which study the origin,the evolution and the structure of the universe from the overall perspective, as well as the structures above the supercluster. In many models of the universe,the Standard Cosmological Model established by Freedman, Robert and Walker is a most important one. In this model the universe came from a big bang, after a series of complex evolution, it became Today’s appearance.In recent years, with the development of science and technique, more and more observations have already indicated that our universe is undergoing an accelerating expansion, Most of physical scientists believe that the accelerating expansion of universe is caused a kind of exotic energy, called dark energy.People designed a lot of model for dark energy. in which the Comparative Cosmological Constant Model, the Quintessence Model, the Phantom Model and Quintom model is relative famous. In addition, the Modified Gravity Theory is also an important theory to explain the accelerated expansion of the universe.The discovery of the accelerating expansion of the universe made it possible to put forward more ideas for the ending of universe. In Phantom field, density of dark energy wound become infinity and our universe wound lead to big rip. Some people raise a concept called little rip later, which is another sequel of universe. Not long ago Frampton et al advanced a concept called pseudo rip, it means that the density of dark energy tend to a constant,when time tend to infinite. In the case of pseudo rip.the whole universe will not turn to big rip, but some structure still have the possibility of rip in future.Many researches have been done for big rip and little rip,so this thesis studied pseudo rip instead. In the third chapter this thesis discussed the basic property of pseudo rip. analysed the state of cosmology basic parameters in the case of Pseudo Rip,such as the energy density, pressure, the state equation and the inertial force. If the universe is the outcome of Pseudo rip, the Cosmological Constant is very likely to be the dark energy.We hypothesis the universe is a sort of perfect fluid in a common sense, which have nothing in viscous. In fourth chapter of thesis, let us analyse the changed state of Pseudo Rip in viscous fluid. Viscous fluid can generate kind of effect such as shear, expansion, torsion and so on, in which expansion would change the pressure of the universe, eventually probable make the universe turn into Little Rip.In fifth chapter of thesis, this thesis researched the nature of single scalar field and two scalar field in the case of pseudo rip. If the ending of the universe is Pseudo Rip,the value of Lagrangian of the kinetic energy term would become very small in scalar field, and even gradually tends to0, left only the potential energy term. Perturbation Theory is an important theory of cosmology, so this chapter focuses on the analysis of the scalar field’s demand for the form of Harbert Constant under disturbances. Unlike other universe ending, Harbert constant tends to infinity in Pseudo Rip, in other words, the various parameters are relatively stable, so we can choose appropriate kinetic coefficients to make sure that the scalar field’s stability under disturbances have no relationship with the coefficients of Harbert Constant. We an also choose appropriate kinetic coefficients to make it have no elationship with specific forms of Hubble rate.