James Blish And The Megamultiverse II

I previously thought that the single immutable timelines of The Corridors Of Time and There Will Be Time, the single mutable timeline of the Time Patrol series and the parallel multiple timelines of the Old Phoenix Sequence were mutually incompatible cosmologies but now think that all of these scenarios can be accommodated within the multidimensional framework mentioned in the opening Time Patrol story although the immutable timelines would have to occupy a remote and usually inaccessible region of the megamultiverse.

Prima facie, James Blish's Haertel Scholium presents a mini-multiverse, its four divergent branches dealing respectively with telepathy, energy beings, the Dirac transmitter and the planet Lithia. (The single Lithian novel is also Volume III of After Such Knowledge.) However, the Dirac transmitter "branch" denies that there are "branches of time." Its protagonists work to ensure that they continue to inhabit a single consistent timeline. So maybe the alternative future histories of the Haertel Scholium do present mutually incompatible fictional narratives?