Complex sentence: Kurzweil opens by explaining that the frequency of universe-wide events has been slowing down since the big bang, while evolution has been ticking off significant milestones at an ever quicker pace.
Split into simpler sentences: Kurzweil opens by explaining that the frequency of universe-wide events has been slowing down since the big bang. Meanwhile he says evolution has been ticking off significant milestones at an ever quicker pace.