I want to meet you at the intersection of reality and existence.
Reality is immutable things. Think of pi or the amplituhedron.
Existence is the universe of three dimensions and time. A trillion spinning galaxies expanding ever faster into the void.
Where do reality and existence meet?
According to string theory, right here. All of spacetime is a hologram, which is projected from a two-dimensional surface - the boundary of the universe.
And where is this cosmic boundary?
If we look outward, we face the problem of spacetime's curvature. There are two possibilities - and neither has a boundary:
It is possible that space exists as a sphere, which is how we visualize the universe in popular imagination. We have no observational evidence for this. But the mind feels far more comfortable with it than with its alternative - which is that space is exceedingly flat. That's the universe we actually observe.
If space really and truly >is< flat, then it expands forever - and there are forever worlds of every possible configuration of atoms, including forever worlds of you and me. It also means, matter and energy open into infinity!
Will we let cosmology convince us that space extends far, far beyond the visual horizon, into the forever realms, where infinity holds all possible variations of our being (and nonbeing)?
Infinity places each of us at the intersection of reality and existence.
There is another cosmic boundary. The very small. The smaller the photon, the greater the energy. At a very compact size, the energy of a photon becomes so great that spacetime curls around it - and it exits our universe through a tiny black hole.
At that energy boundary of the universe, spacetime becomes pixelated, granular, quantized - arranged in discrete pieces suspended in 5-space.
Is this the boundary surface from where cosmic strings vibrating in ten dimensions project the volume of the universe? At this ultimate magnitude of smallness, quantum effects come into play. It is here that existence blurs into the wave function containing the reality of all possible universes.
We meet in the awareness of this intersection of the real, which is infinite, and the particular, which is you, the unearned beauty of consciousness, conscious of the boundary we occupy between now and forever.