I keep hearing that a bubble of true vacuum can get formed when the Higgs field jumps to a higher potential and will engulf the entire universe eventually.
If a bubble of true vacuum forms near a point near the edge of the visible universe, it would never reach us due to the expansion of space. So the doomsday scenario predicted may not really occur.
So the question is, would an expanding bubble of true vacuum really engulf the entire universe or only part of it?
In an accelerating expanding universe vacuum decay can be merely a local disaster.
This is because there is a cosmological event horizon: given a certain event there are points too far away to ever be reached by a light signal (or vacuum decay). The distance to this horizon is time dependent (today about 5 Gpc).
Note that this is true only as long as the universe expands at an accelerating pace. One possibility that has been suggested is that the true vacuum has zero cosmological constant. So the inside of the transformed region may well expand in a different fashion without any event horizons. But the expansion outwards will still be limited by the causal structure of the outside universe.
