PARALLELOS

Almost 13.7 billion years ago, Cosmos was an infinitesimal singularity. Based on Big Bang theory, some unknown trigger expanded to inflate the three-dimensional space. As the immense energy of this initial expansion cooled, light began to shine through. Eventually, the small particles (molecules/atoms) began to form into the larger pieces of matter (energy) inclining towards quantum entanglement forming the galaxies, stars and planets.

One questionable aspect revives whether any parallel universe exists?

With our current technology, we are only limited to observations within this universe because the universe appears to be curved and we are dwelling inside the fishbowl, unable to see the outer realms.

Is our universe unique?

The answer could be other universes exist besides our very own, where all the choices you made in this lifetime played out in alternate realities. The concept imparts as a "parallel universe," and is a facet of the astronomical theory of the multiverse.