I've been trying to find some sort of evidence-based explanation of the BigBang. Perhaps something about the observed distance of stars changing over time as the Universe expands. I've seen claims that a mysterious radiation found was evidence, but that seems fairly loosely connected. Does this have any of that? I know we've discovered Pluto's 4 moons from 1978 to 2012. I don't think we have a true understanding of what causes gravity (outside of an equation/constant) despite it being readily observable in our daily lives. Is this an evidence based book or more theory?