There are many layers to this question, as you know from your scientific background. This is the fundamental theme that has perplexed scientists and philosophers alike.
You could also ask the question: “Who am I, and why am I here?”
You are the Universe, and the Universe is you. As you know from your Enlightenment, you have no beginning and no end. Likewise, neither has the Universe.
All is One.
But now let us look at it from another angle.
From an outpouring of Spiritual Love in its highest form, all the atoms are ordered and form every aspect of the Universe. So all is formed from Love — the joining principle.
Think of it like a giant kaleidoscope: the cylindrical casing containing coloured pieces which can create a myriad of shapes and formations.
Constantly, there is an outpouring of Universal Energy. Minuscule particles, which we could call Spiritual Atoms, are endlessly being arranged and rearranged throughout Creation at large.
There is no Big Bang where the Universe was created. It has always been and always will be. Everything simply changes its form.
What you call life is a temporary vehicle where Consciousness resides for a short while and then departs.
Beautiful