In this book we will frequently talk about measurements and the various dimensional units given to the outcome of these, i.e., their results. Dimensional units are fundamental if physics processes are to be quantified and compared with each other. Moreover, in astrophysics and cosmology the scales or the range of magnitudes play a decisive role, and frequently comprehension seems to fade when trying to map cosmological quantities onto our small personal domain of life. This remains a perpetual challenge even for scientists, who deal with these issues professionally on a daily basis.