In New Avengers #2, Reed Richards presents the crisis to the Illuminati. He describes that the current issue with 'incursions' started when 'an event' occurred on a parallel Earth, which caused the premature death of that Earth's universe. Since I don't read many Marvel comics, I'm wondering if I missed something that was detailed in another comic.
What happened to destroy that parallel Earth and its universe? What was this 'event' that Richards refers to?