I have my money on vacuum decay, personally.
Overall, this was a fun read—oscillating between things I couldn’t hope to understand and fun quips that bring the whole book back down to earth.
The book rambled a bit; it felt a bit like how a professor rambles between one subject and the next. Don’t get me wrong, this is a positive in my opinion.
Learning about cosmology really helps to put everything in perspective. It’s good to remind oneself that nothing really matters in the end. We’re insignificant in the vastness of the universe!