Do black holes mean that the universe is safe?

The universe isn't safe?  It's a frightening thought, but let me put your mind at rest, at least a bit.  According to some ideas about physics the universe could collapse into a different type of universe at any time.  This is astronomically unlikely to happen while humans are around, and it would not be all at once.  A tiny flicker of a quantum event at one point in space could start it off, and then it would spread at the speed of light.  However, the universe is extremely big and expanding at an accelerating rate.  If the collapse happens in a distant part of the universe it may never reach us.  But really, don't worry, it's so very, very unlikely to happen while anyone is around.

What could make it happen fast is having vast amounts of energy concentrated in one place, kicking space around enough to make it able to flip into a different state.  But, there isn't anywhere around in the universe where that kind of concentrated energy can be found.  Or is there?

Black holes are only black because we aren't close.  Very strange things happen at the edge of a black hole if you can get very close to that edge and hover there, or if you can observe very close to that edge from a distance - things will get very, very hot, if current theories are right.  All the information associated with whatever falls into the black hole appears as thermalised radiation at the event horizon, and that radiation is very hot indeed, perhaps the hottest thing possible in our universe.

And so, if theories are true about black holes, it may be that close to their surfaces space is blasted with such intense heat that if it was going to collapse, it would have, and there are so many black holes around us that the universe should have been destroyed.

Perhaps the intense heat of black holes means we are safe from any possible collapse of the universe, no matter how incredibly unlikely!