There are particles in so-called “empty space” that spontaneously pop in and out of existence all the time. Turns out space isn’t really empty at all, but rather seething with quantum energy.
Which leads to the question of what created those particles and quantum energy.
Your guess is as good as mine. But the idea of these particles spontaneously appearing out of nowhere is often used as a possible explanation for how the universe began. ie, it just spontaneously arose out of complete nothingness. My hunch is there are some things we simply can’t ever know.