Lad tiden gå (English: Let time pass) is a 1986 science fiction novel by Danish modernist writer Svend Aage Madsen.

This novel is a typical example of the third phase in Madsen's writing that's like most of his later works is set in the town of Aarhus and has several characters that also appear in his other books (Johanna, Sverre).

It also has another typical feature of Madsen's books - a complicated timeline of the novel having chapters describing overlapping periods of time.

Johanna who is a lector at a Danish university gets involved by her colleague professor Jeyde in a time travel experiment.

[2] This way Johanna gets the unique chance to outplay different variations of her relationship with Sverre, one of her students, as she can always correct a mistake that she has made.