To ease your mind, even if humanity lives for a million more years, I doubt we will ever know what's outside the universe. It's just so vast, we'll probably never even leave our galaxy as a species, the space between our galactic neighbors is too vast. Let alone traveling between galactic clusters.

But sometimes, not knowing everything is alright too. Our lives are a mere speck when compared to the life of the universe.

The scariest are the ones we have not yet discovered. The universe is so freaking big, our tiny brains can't comprehend its size. We'll never truly know everything that's out there.

Could be an incredible number of alien civilizations, both hostile or peaceful, or it could be, there's nothing and we are the only ones. There are also gamma ray bursts, we wouldn't know, but one could be heading to us right now.

And so much more...