The Modern World, or Mortal Realm, also known as Earth, is the realm where mortal humans dwell. The Mortal Realm is riddled with vast cities and signs of destruction from the past. The largest cities include Toronto, ON with a population of 29 million followed by Montreal, QC with 19 million, and Jerusalem after it's expansion with 18.5 million.
The inhabitants of the Mortal Realm make use of ecologically dangerous technology, draining their land of resources and life. A breakthrough in the mid 22nd century created a substance that could be formed into a muscle structure to be applied to armour, which would harden on impact. After years of experimenting with nuclear energy, multiple nuclear plants in Russia exploded for unknown reasons, destroying most of Moscow in the mid 27th century, resulting in most of the world turning their back on nuclear energy.
Most inhabitants of the Mortal Realm should know nothing of the Celestial Realm or it's inhabitants. Only though folklore and fantasy tales would anybody know of the Celestial Realm, other than face to face contact by a Celestial Dweller.