I think it’s the end of Men in Black where it turns out the milky way is the inside of an alien’s marble – that sort of thing!
Indeed. The universe was formed by an explosion, which is still happening as the universe is expanding.
So like all explosions that will eventually stop and either end abruptly, or the tailing edge will catch up .
I’ve no idea the mechanics of an explosion.
I think what should be thought about is(in relation to your men in black scenario) is what is happening inside an explosion. What is being formed in the expanding gases. Are they swirling in turmoil, creating little eddies, that go on for so long then petre(peter?) out.
And if thats the case then we, and our galaxy and all the other phenomena are just these little eddies.