(Original Review, 1980-11-06)

The most well thought out model of time-travel I have ever seen in a novel was in Hogan's "Thrice Upon a Time". This book ascribes to the "reset" theory of world-lines; if you send a message into the past (no matter travels cross-time in this book but it doesn't seem to be ruled out) that says "kill me, I am about to do something very rude in the present, and I should really be stopped", then the people back then get to act on the information while you wait in the present, with your teeth clenched, for the effects of your message to ripple forward and absolve (dissolve?) you. Time travels at several rates herein. From your point of view you are waiting for the world-line to readjust (a somewhat faster process than normal forward running since only the new ripples have to be worked in). From the point of view of your cohorts in the past, they are living just like they normally would. What bothered me about this model is that it made actions free, with no consequences. For example, X makes a boo-boo that will ultimately destroy the world, and sends a message into the past to warn the earlier version of X not to make that mistake. It turns the whole universe into a big experiment. You don't like the results, you change it before it happened. (Imagine the amusement parks. You can become "torturer for a day" and can even tell yourself about all the fun you had before that version of you gets erased and the normal reality gets reinstated.)

I would add the following wrinkle: Rather than have realities disappear, let them stay around. What I am getting at is a bubble theory of reality. There is a time-line (call it super-time) which numbers all possible moments in the universe. Life progresses from one number to the next just as we are used to. If you go back in time from moment 55 to moment 23 and kill your grandmother, great. She's dead, and a bubble starts moving up from 23 in which you is never born. Meanwhile, up at time 55, your home reality is happily progressing, complete with a confused and guilty you in it who has pre-formed this sickening deed and has returned to find the same old grind. You don't have her inheritance. In fact, the old bag is still hopping around. (The effects don't propagate that way.) This doesn't mean that one bubble can't effect another. You can communicate with the future (or the past) by just setting your transmitter to T+22,000 (or to T-22,000). For as long as you talk, the same guy will be at the other end of the line.

One curious thing about this model is that past becomes a resource which is constantly consumed. The reason is that whenever a bubble gets started, it gradually overwrites each successive moment of super-time. Once overwritten, their old contents are gone, and your precious past has been consumed as though in a fire.

Maybe I should write to Hogan about a new book. Then again, is he on the net?

[2018 EDIT: This review was written at the time as I was running my own personal BBS server. Much of the language of this and other reviews written in 1980 reflect a very particular kind of language: what I call now in retrospect a “BBS language”.] ( )

A great read from the early eighties, which is when I first read it. The work has aged well. Totally convincing resolution of the time-traveler paradox. ( )

got to p. 44 of the 310 p. edition, went to GR to find out whether I should keep struggling, decided not to.... apparently this takes 'exploration of ideas' too far and just dumps any pretense of story or characterization.... sorry

This book was good. It did take me time to get into the story because there was so much technical / programming stuff. But once I got the hang of that it was good. Usually if I cannot get into the book fast enough I give up and move on. This story kept me hooked however and is worth the read. ( )

I'm afraid I agree with an Amazon review I saw that this would have done much better as a short story or novella. This is a work of hard science fiction, with an emphasis on hard science and not so good on the fiction. Hogan has done better--I quite liked his characters in Realtime Interrupt, but here, although it's a great idea, I just don't find the ideas compelling enough to make up for a weak plot and characters. This isn't the usual time travel book and I do appreciate all the thought Hogan put into grounding his concept--no, wait, excuse me, I lied. I don't appreciate all the time spent grounding the concept. I was bored. Very little other than the breaking/not breaking of a jar happens for the first hundred pages. I did like the Scottish setting--it made for a nice change compared to all the American (or America in Space) settings you usually see in science fiction. But this just never came alive for me, no matter how clever the overall concept. ( )