Primordial gravitational waves offer unique insights into the inflationary period and subsequent thermal history of the Universe. The spectrum of primordial high-frequency gravitational waves is...Show morePrimordial gravitational waves offer unique insights into the inflationary period and subsequent thermal history of the Universe. The spectrum of primordial high-frequency gravitational waves is highly sensitive to the processes in the early Universe and can be significantly suppressed during an epoch of early matter domination (EMD) induced by new long-lived massive particles. This damping effect is studied with numerical and analytic methods. The relative energy density of gravitational waves today is found to scale with the wavenumber k as k^(-2) for waves crossing the horizon during the EMD epoch. The overall damping between the start and the end of the EMD epoch is given by m^(4/3) Γ^(-2/3)M^(-2/3), where m and Γ are the mass and decay width of the long-lived particles correspondingly, and M is the Planck mass. For concrete examples of EMD, models with inflaton decay and heavy neutral leptons are considered. Experimental observation of stochastic gravitational wave background could probe early cosmological events and constrain new physics scenarios.Show less
Bitcoin, since its birth in 2009, has been subject to large debates on multiple dimensions, especially on the question whether it embodies a viable monetary alternative to fiat currencies. Previous...Show moreBitcoin, since its birth in 2009, has been subject to large debates on multiple dimensions, especially on the question whether it embodies a viable monetary alternative to fiat currencies. Previous research has suggested that in countries dealing with severe inflation, Bitcoin can indeed have helpful monetary implications. This thesis is concerned partly with finding out the exact relationship between inflation and Bitcoin usage via regression analysis, as empirical support for the notion that they are positively associated is currently lacking. Additionally, a case study considering Argentina is conducted to gain a deeper understanding about the possible correlation between inflation and Bitcoin usage. Argentina is an example of a country under enormous inflationary pressure, and the literature indicates that Bitcoin is being used here to evade value losses from depreciation of the domestic currency. Two ways can be deduced from theory about the exact way Bitcoin fulfills this role, involving either its “store of value” or its “vehicle currency” function. Via a survey design combined with a content analysis, there is aimed to identify which role is more significant in the Argentinian context. Finally, there is reflected on the findings in the light of preceding theory, and implications are discussed for a range of different actors.Show less
