According to people who know about such things, there is not enough observable matter in the universe to account for the gravitational behaviour of the universe. In fact, we can't account for 80% of the matter that should be out there. They call this "dark matter."
Some theorists propose that this dark matter exists in dimensions that we cannot see.
If that which we call "spiritual" exists it will consist of something, otherwise it won't exist. WHAT IF the dark matter of the universe exists in that dimension the religions call "heaven."