Sunday 16 February 2014

Clean Cold Winds

Poul Anderson, The Shield Of Time (New York, 1991).

For story purposes, all that Poul Anderson needs to tell us is that a group of Time Patrol agents flies from a temple of  Poseidon to the city of Bactra. Instead, we read this vivid descriptive paragraph:

"The three hoppers lifted high enough to be no more than glints to any eyes that might chance to catch them, and glided toward Bactra. Below them the land rolled vast from the mountains in the south, fields green and brown, spotted with trees and tiny buildings, the river mercury-bright, the city and the invader camp toylike. No hint of hatred and misery reached these clean cold winds, save what the riders bore with them." (p. 116)

Anderson never forgets that his characters move through an environment that should be kept constantly before his readers' minds - almost as if they were watching a film.

I am not always sure about what Anderson is doing with temporal paradoxes. Everard warns colleagues:

"'...we will not play games with causality and risk setting off a temporal vortex...'" (p. 116)

He means, in this case, that he and one other agent will attempt to arrest the Exaltationists but that, even if they fail and are killed, the other Patrollers watching from a distance must not travel back in time to prevent them from being killed. But what is a temporal vortex and how could one be "set off" by such an attempt to change the past?

In this story, the Patrol has "'...been tinkering with reality...'" (p. 122). A Patrolman masquerading as a Soviet Army captain planted some fake archaeological evidence in 1985, then this was "'...removed, annulled.'" (ibid.) How might this have been done?

Let us suppose that the "captain" was based in the Patrol Academy in the Oligocene. From there, he travels to 1985 to plant the evidence. In 1987, there is press coverage of the recently discovered letter from Antiochus. This induces the remaining four Exaltationists to travel to 209 BC, when they are apprehended by the Patrol. When milieu HQ in Moscow, 1890-1910, has been informed of Patrol success in 209 BC (two Exaltationists killed, two arrested), HQ sends a message to the "captain" at the Academy telling him not to travel forward with his faked evidence to 1985. This annuls:

an event in 1985 - the "captain" handing the metal box containing the forged latter to Private Garshin;
the press coverage in 1987;
the Exaltationists reading that press coverage and drawing conclusions from it;
a conversation in 1987 during which Shalten of the Patrol informed Everard of the letter and the press coverage.

However, it does not prevent the Exaltationists from having arrived in 209 BC and been killed or arrested by the Patrol. We are told that time travelers in a deleted timeline are deleted with it so is this what happens to the Exaltationists who read the news reports and to the Shalten and Everard who discussed those reports?

At the end of the story but back in 1902, Shalten tells Everard:

"'In your position among us, you need to know the whole truth. For you to learn it later in this century could pose a hazard. Causational loops can be very subtle. Your experiences and accomplishments in Bactria [in 209 BC] must continue to have happened. Therefore you must be informed well pastward of our preparations for them.'" (ibid.)

But Everard's activities in 209 BC are well "pastward" of any events in the twentieth century and therefore cannot cease to have happened even if some of those twentieth century events are changed. Shalten is speaking to the Everard who did defeat the Exaltationists in 209 BC. That Everard is not going to forget what he did in Bactra, let alone cease to have done it. Now that the events in 209 BC have safely happened, Shalten feels it is better (I am not sure why) to delete the planting of the evidence and the events that followed from that even including a 1987 conversation between himself and Everard. I do not understand why, after all this, he thinks that he needs to discuss the matter with Everard in 1902 in order to keep the timeline the way he wants it.

Addendum, 17 Feb '14: Maybe, for the Time Patrol scheme to work, the "captain" would have to set off not from the Oligocene but from a date between 209 BC and 1985 AD. Thus, the prevention of his departure from that intermediate date would delete the forgery-related events in the twentieth century but would not prevent the Exaltationists from having arrived in 209 BC. (I woke up in the night dreading that someone else would make this point before I did.)

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