Those of us who love Time Travel – I mean the Time Travel genre, the real thing, with a time machine which, at the click of a button whisks you backwards or forwards through Time with a capital T – have been having a lean time of it lately.
I even thought of writing one myself (on the "if you want a job done properly" principle) and got as far as mapping out a story in which I brought Time Travel and Past Lives together, my heroine sorting out problems she had gone through, is still going through, in previous lives, but only she, of course, knows that she and they are in a very real sense the same person.
An interesting idea, but I never came up with a good plot and – well, you know, it's somewhere among my files ...
Paul Levinson, unlike me, comes up not only with a great, attention-grabbing idea but a plot that carries the reader along like a river – should I say the river of time? – in flood, with multiple sub-plots swirling around ... I'm getting carried away here myself.
Back to reality. And by that I mean real time. Which in this case is AD 2042, in New York – at the bottom of the first page, page 13. Athens AD 2042, in the top half of the first page, is not real time at all. You will understand that by the time you finish the book and turn back for another glance at the first page as I usually do.
Sierra, a doctoral student specialising in some rather recherché aspect of ancient Athens, I had no trouble at all in identifying with, and by the second page I was hooked. And it is on the second page (no messing about here) that Thomas O'Leary, one of her supervisors, hands her a five-page fragment of a hitherto unknown Socratic dialogue.
Naturally, she is sceptical. She is a scholar; Plato is notoriously easy to imitate and there have been other hoaxes. But when, later, at home, after a hot shower, she curls up on the sofa and reads it through, then in astonishment reads it through again, she knows that this is something totally different. A visitor to Socrates in his prison during the final hours before he drinks the fatal hemlock (and presumably after the departure of Critias) tries to persuade Socrates to leave and accompany him to life and freedom.
How is this different from Critias' persuasion?
Well, this visitor, Andros, is a time-traveller, and has with him a mindless clone of Socrates that can be left there dead in Socrates' place when they leave.
Socrates declines the offer. End of fragment.
But that weekend Thomas O'Leary disappears. And searching for him, Sierra finds herself caught up in the plot to save Socrates.
All perfect, classic SF Time Travel.
But what about the theory? For a certain amount of reasonable scientific (or at any rate pseudo-scientific) theorising is what distinguishes real SF (Science Fiction) from unreal SF (Speculative Fantasy).
Heron, an Alexandrian inventor, who turns out to be (to have been) a traveller from the far future and the inventor of these "chairs" that carry one through Time, tells Alcibiades that Heraclitus was "one of the greatest thinkers of all time". (Yes, Alcibiades is in the story, too – he and Sierra fall head over heels and make love at various times – and I mean various different times. You see why I identify with her?)
"Heraclitus recognised that you can never step into the same river, exactly the same river, twice, because new water is always flowing. And yet we are right in thinking there is a reality to the river Maeander, a reality which endures, and makes the river Maeander distinct from any other river, such as the river Cayster. So the river always changes, yet stays the same, has continuity – both are true.
"And what is true of rivers, of all existence, is also true of time itself, because time is part of existence," Heron continued. "I, and others throughout history, have recognised that essential point. And if that is so, then travel from one time to another should be possible, even easy, since, even though time always moves, it also stays the same – stands still, is the same time."
And as the book moves on, and events have begun to influence the past, to change history, Sierra begins to realise that what they are in fact doing is bringing into being alternative universes, not changing the history of the one she grew up in, the one that existed before she was handed that fragment of dialogue.
For instance, speaking of Alcibiades when she knows he is going into danger, she says, "He is dead already, in one universe. I want to make sure he stays alive in this one."
And wondering what Plato is doing "now", she asks herself what Plato had done at this time in the original history – the history of the world she had grown up in, before she had been drawn into this. Not much was known about him in those years.
All this – Herclitus and alternative universes – is metaphysics, though, not science as such. And we are given no inkling of how these "chairs" work or even might work.
But that is a small complaint, from one who is all too willing to suspend disbelief when reading a good story. Which this is, believe me.