Could the universe have happened another way?

Astro-physicists amuse themselves by designing alternative universes, and there is no prima facie reason why one of them might not have been realised in practice, but the overwhelming majority of them wouldn't be capable of chemistry, of course.

All things in nature seem to have similar beginnings and endings. If we could come into being another way I don't see why other things couldn't have more than a one way street as well. I am not sure what you mean by could the universe still be here. I do think that our universe will one day end. After all if it had a beginning it probably will have an end. Could the end become a new beginning universe I think so. If that is what you are implying. The law of matter/energy is that it is interchangeable. If it (matter/energy) always was, like the earth, solar system, milky way and all existence this will continue to morph into new things. The singularity is just a resting point with the event of the big bang everything was set into motion. The universe is a perpetual motion machine. It is conceivable that one day the mother of all black holes will form and suck everything into a neatly pack, dense, organized singularity where it again will experience a new event and start a new.

We do not know.

At the moment we do not see any particular reason why not . . . but right now it we do not even know enough about what we would need to know to answer this question.

Maybe there is a lot of degrees of freedom on how a universe can form - and either we are a colossal coincidence, or there are gazillions of universes being formed.

Maybe there are very few degrees of freedom, and any universe would look very similar to ours.

Right now it is all speculation either way.

Who says the universe "came into" existence?

That implies that existence goes beyond the universe.

Since the two words mean the same thing, the universe IS existence, by definition.

- the realm within which all things can be said to exist.

This specific universe is true. For the most part. Hold on there's someone at the door.

Sure, it could have; it would just be in a different configuration than it is now.

now you should wonder about parallel universes

Another way then what?

who knows?

Multiverse...look it up.