COLLIDING BLACK HOLES CAN CREATE BUBBLES THAT SWALLOW THE UNIVERSE

In the region between two large black holes that are about to collide a 'real vacuum' could develop. That is a bubble of empty space that quickly spreads around itself and can swallow the entire universe. Physicists have known for some time that our universe may not be in the lowest possible energy state. Instead of the universe forming a 'true vacuum', it could be in a state that physicists call a 'false vacuum'. A false vacuum is not stable. This means that it can still revert to the 'real' variant. If that happens somewhere in the universe, it would form a bubble in which all the laws of nature are rendered meaningless. And worse, this bubble in which the real vacuum reigns, would expand at the speed of light. In this way it would spread throughout the universe and eventually swallow everything. Some researchers think that the extreme gravity near a black hole can create miniscule bubbles containing such a real vacuum. As long as those bubbles immediately fall into the black hole that's no problem. They can then exist for a short time without having the chance to grow and destroy the universe. But if vacuum bubbles actually form, physicists can't be sure they'll fall into the black hole. It is knowing if this were to happen, these bubbles would begin to expand quickly and reach the speed of light in a very short amount of time. If they are beyond the black hole event horizon they may continue to grow, rather than fall into it. This would be a disaster of apocalyptic proportions. The universe would cease to exist.