The Assumption is not a metaphor
We must be very clear on this point: The Assumption is not a metaphor. The Blessed Virgin Mary was really taken up, her physical body was transformed. Pope Pius XII in Munificentissimus Deus (1950) declared that Mary, “after the completion of her earthly life, was assumed body and soul into the glory of heaven.” Both BODY and SOUL! This means that her physical body was transformed and glorified (in a manner identical to Christ’s after his Resurrection), her soul was perfected with the Beatific Vision, and she was taken up.
Is heaven a place?
In the General Audience of 21 July 1999, Pope John Paul II stated that heaven “is neither an abstraction nor a physical place in the clouds, but a living, personal relationship with the Holy Trinity.” In this statement, as (almost) always, the great Holy Father was in perfect accord with St. Thomas Aquinas – “Incorporeal things are not in place after a manner known and familiar to us, in which way we say that bodies are properly in place; but they are in place after a manner befitting spiritual substances, a manner that cannot be fully manifest to us” (ST Supplement, q.69, a.1, ad 1).
What John Paul II wished to stress, and what is especially important to consider today, is that heaven is not to be understood in terrestrial terms. Heaven is primarily a state of being and is certainly not a ‘place’ in the worldly sense of the term.
Nevertheless, we come to a difficulty when we ask: Where did Mary’s (and Christ’s) body go? The simplest answer is: Heaven! But then we wonder: If heaven isn’t a place in the ordinary sense of the word, how could there be real human bodies present there?
The words of Reginald Garrigou-Lagrange (who taught John Paul II and oversaw his doctoral work) are most helpful: “Heaven means this place, and especially this condition, of supreme beatitude. Had God created no bodies, but only pure spirits, heaven would not need to be a place; it would signify merely the state of the angels who rejoice in the possession of God. But in fact heaven is also a place. There we find the humanity of Jesus, the Blessed Virgin Mary, the angels, and the souls of the saints. Though we cannot say with certitude where this place is to be found, or what its relation is to the whole universe, revelation does not allow us to doubt of its existence.” (From Life Everlasting)
Now do not think that John Paul II had contradicted his teacher when he said that heaven is not a physical place in the clouds! Garrigou-Lagrange and the great Pontiff are both getting at the same point: Heaven is first and foremost union with God; secondarily, heaven is the place where the bodies of Jesus and Mary abide, but this ‘place’ is not like every other place we think of – its relation to our universe is not clear. Glorified bodies are very different than non-glorified bodies (though they are essentially the same). A glorified body does not move and take up space in exactly the same way as a non-glorified body does. Still, the glorified bodies of Jesus and Mary are somewhere, but this ‘somewhere’ will necessarily be a ‘place’ which is ‘glorified’ – just as the glorified body is different from non-glorified body, it resides in a ‘glorified place’ which is different from a non-glorified physical place. [This is my own reasoning and not an official Church teaching.]
Where is heaven?
The simple answer is: This has not yet been revealed to us. However, we can say that it is certainly not on earth. Neither is it within the earth. It is not in clouds either. Heaven may be somewhere in our universe, far off – though we must be careful not to fall back into our terrestrial categories of space, distance, and location.
Perhaps it is most likely that heaven is outside the universe in what some Thomists have called “uncontained place”. In ST III, q.57, a.4, ad 2 (which is not in the oldest and best manuscripts) we read: “A place implies the notion of containing; hence the first container has the formality of first place, and such is the first heaven. Therefore, bodies need themselves to be in a place, insofar as they are contained by a heavenly body. But glorified bodies, Christ’s especially, do not stand in need of being so contained, because they draw nothing from the heavenly bodies, but from God through the soul. So there is nothing to prevent Christ’s body from being beyond the containing radius of the heavenly bodies, and not in a containing place. Nor is there need for a vacuum to exist outside heaven, since there is no place there, nor is there any potentiality susceptive of a body, but the potentiality of reaching thither lies in Christ.”
This argument from the Summa claims that, because the glorified body in no way relies upon the non-glorified world, neither does it need to be contained in the universe. Thus, the bodies of Jesus and Mary may in fact be outside of the universe, outside of space and time, no longer contained by place. There is no space or place outside of the universe, but this is where the bodies of Christ and Mary are; since they need not be contained by physical place.
Therefore, it seems most likely that heaven is outside of our universe. It is not a ‘place’ as we usually think of ‘place’, but is a ‘non-containing place’, a ‘glorified place’. The glorified physical bodies of Jesus and Mary reside there.