Dunno. There's some mind boggling astrophysics going on, and from what Strange has told me, it has to do with some other universe trying to collide with ours to eat us all and Strange using a time stone to stop it. After being warned it could cause all sorts of bad side effects.
Or it may be more than that, like multiverse more, and we're just in a time-space nexus that connects to a bunch of wormholes from other places.
Going to blame magic though, since it explains why our situation can't be replicated in models, no matter how we've tried to crunch the numbers or scan things.