I've been toying with the metaphor of heaven as another dimension for many years. I remember a good conversation about it with my mother, maybe 25 years ago. Then more than ten years ago my thinking about the other world was much enriched by John O'Donohue in his valuable book, Anam Cara. Here is an outstanding paragraph, minus the Irish words:
The eternal is not elsewhere; it is not distant. There is nothing as near as the eternal. This is captured in a lovely Celtic phrase, "The land of eternal youth is behind the house, a beautiful land fluent within itself." The eternal world and the mortal world are not parallel, rather they are fused. The beautiful Gaelic phrase, "woven into and through each other," captures this.