Cosmological observations indicate that our universe is accelerating at the present epoch. Within the framework of Einstein’s General Relativity, this accelerated expansion indicates the existence of some exotic matter known as Dark Energy. Understanding the nature of dark energy is one of the biggest challenges in physics today. Dark energy not only influences the rate of expansion of the universe but also governs the growth of large scale structures.
This naturally raises the following question: Can we uniquely characterize the nature of dark energy if we could observationally determine the cosmic expansion rate and the distribution of large scale structures in the universe?
In this talk, I shall mainly focus on this question besides presenting the details of the role played by the perturbations in dark energy in structure formation.