A classical objection maintained that reaching heaven would require extraordinary speed and that such speed was impossible for a body. The response invoked familiar instances of rapid motion to show that ordinary human movement is not the measure of every possibility.
These are illustrative rational replies, not scientific measurements of the Ascension’s velocity or of astronomical distances.
Saying “I do not know the mechanism or speed of the journey” expresses limited knowledge. It should not be confused with the much stronger claim “the journey is impossible under all circumstances.”