Part one- well, comparison to cosmic rays was reassuring. I wonder why I haven't heard that said before, seems a simple enough argument. I liked that there was a graph. Switching from commentary to camera to lecture, repeating some of the same information, was a bit annoying, especially as the sound quality is bad for that second half. I would have much preferred if it was done as a whole presentation for the one purpose, with good sound quality.
Part 2- starts with a repeat of the introductory material of part 1. Feels like my time is being wasted especially after the long title sequence, that I have now seen twice. It was good that the Stephen Hawking worry was explained. The Spock parallel universe story was not really dealt with. Part 1 explained that detecting parallel universes wasn't really applicable but that isn't said at the end of part 2 - we are left with a joke about evil Spock's beard, not a conclusion.