In this dissertation, we explore two aspects of the dark matter using cosmology. In Chapter 2, we study the interaction between axion, a famous dark matter candidate, and ordinary matter, through their trace left in the thermal history of the universe. We show that the axion- matter coupling can be constrained by the effective number of relativistic species, Neff, with next-generation CMB experiments. In Chapter 3, we study the distribution of matter before inflation, by conducting massive galaxy surveys of the large-scale structure of the universe. We show that the measurement of the primordial non-gaussianity of matter distribution can be significantly optimized by various techniques and strategies for ongoing and futuristic surveys.

Hegel is often interpreted as undertaking two independent projects. Hegel is praised for his insight into the connection between the theory, artwork, religion, and concrete way of life of various cultures. However, Hegel is condemned for constructing an “Absolute” system of knowing that selectively focuses on his own culture’s theory, ethical attitudes, and way of life. Hegel is often interpreted as understanding his Absolute as the pinnacle of human knowledge that reconciles all normative and theoretical conflicts within past cultural worldviews and ways of life. This bi-furcation is especially pronounced in scholarship on Hegel’s Lecture on Aesthetics. Many scholars suggest we ignore Hegel’s discussions of the Absolute and attend only to his discussion of particular artistic works and movements. In this dissertation, I first provide an alternative reading of Hegel’s Absolute. For Hegel, any articulation of the Absolute is also an act of reconciliation (versöhnung). Reconciliation aspires to redeem theoretical and normative conflict by re-framing natural laws and ethical principles as synchronized with the concrete reality of particular peoples, social institutions, and empirical observations. In this way, reconciliation grounds individuals in universal principles that orient them towards harmony within themselves, with each other, and with nature. For Hegel, any conception of the Absolute is justified through its presentation of universal principles that can systematically unify a community’s observations of nature and history into a comprehensive theory, and properly normatively orient that community within that understanding of history and the cosmos. Using this hermeneutic, I will also illustrate how we can read Hegel’s Lectures on Aesthetics as a unified work. On the one hand, Hegel's local cultural insights arise from his understanding of art as a way of expressing the Absolute that produces a proper reconciliation for the historical moment in question. On the other hand, Hegel traces the causes of his own culture’s forms of conflict and alienation as gradually developing throughout the history of art. Thus, Hegel’s theory of the Absolute is integral to his local cultural insights, and the history of those cultures is essential to understanding the purpose of his presentation of the Absolute.

de Sitter spacetime plays a central role in modern (quantum) cosmology. Yet, there are various aspects of quantum field theory in de Sitter that we do not understand at the same level as we do Minkowski spacetime. In particular, perturbative calculations in de Sitter give rise to a variety of contributions that grow with time (secular divergences). We study how such terms can be interpreted using a renormalization group approach, which eventually culminates in an effective theory description of the long wavelength physics. We also introduce techniques to compute loop integrals in de Sitter, a problem for which the standard flat space QFT methods are inadequate. These methods complement and validate the EFT description, and allow us to calculate higher order corrections to the Stochastic Inflation framework for massless scalars.

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