I am not always a fan of science fiction based on alternative timelines. They can be superb, but they are often pedestrian, and too often deeply dumb.

I’ll give you two examples – best and worst. Pavane by Keith Roberts is a powerfully written novel set in a fully realized alternate world. It’s premise, spelled out in a prolog, is that Queen Elizabeth was assassinated, leading to a conquest of England by Catholic Spain. That shows a lot more imagination than the typical, “What if Lee Harvey Oswald had been hit by a bus on the way to Dallas?” setup, but the story didn’t need the premise. If the prolog had been left out and the story had been marketed as fantasy, it would have been just as good.

My candidate for worst alternative timeline story is Mirror, Mirror from the original Star Trek. While it is fun to see an alternative Spock, the notion that the entire course of human history had gone down a different and dystopian path, yet still the Enterprise was the Enterprise and all its main characters were still there doing the same jobs is too silly to even laugh at.

Actually, scientific accuracy is rarely invoked. Most alternate timeline stories are just an excuse to explore a situation contrary to fact, and there is nothing wrong with that. It has obviously excused Mirror, Mirror to its many fans. There is a sub-genre of historical novels called alternate history which doesn’t claim to be science fiction at all.

All this is a tortuous route to Heinlein and the novel fragment I posted yesterday. Heinlein’s short stories from the thirties and forties build up a future history that I would have loved to be a part of, or at least to write stories in. Time, however, eventually caught up to them. In our world, Leslie LeCroix was not the first man on the moon. As Heinlein continued to mine his old works, he eventually cast what had been his future history as an alternate timeline. He added more timelines, and eventually let them all blend together into a view of multiple universes. This was great fun for me as a reader, but it held nothing for me as a writer. I was interested in writing about a robust exploration of the solar system in the near future, informed by astronomical information Heinlein did not have.

I asked myself how the world Heinlein wrote about was different from the world we live in. The answer was simple; his culture developed nuclear powered spaceships, and ours didn’t. That begged the question, “Why not?”. We developed nuclear submarines and aircraft carriers, so why not nuclear spacecraft?

Not denying the technical difficulties involved, the answer seemed to be fear. Somewhere on the road to the cold war, nuclear power became the enemy. Nukes took out Hiroshima; nukes gave us Godzilla. Nukes gave us fear, and fear does not deal with reason; it has a logic of its own.

What if that fear had not developed, or had developed differently. It would be easy to envision a timeline in which they developed nuclear space propulsion technology, so we had to follow suit, and to hell with the consequences.

So when and where could we tweak reality, and how should it be done? Should we simply present the chosen future as fait accompli, or should we create a character from the present who would go back in history and cause the change?

Heinlein came to the rescue again. In one of his late novels, in a throwaway line, he mentioned an attempt to change history by sending an agent back, not to kill a horrid dictator, but to give a condom to his father, an acne-faced teenager, on the night the dictator had been accidentally conceived. Beautiful!

I decided to save Franklin Roosevelt’s life, or at least prolong it for an additional several years, to make things come out differently in a different timeline. opening chapters Wednesday and Thursday