Eddies: Mainwethering II

Poul Anderson, Time Patrol (New York, 2006).

Mainwethering in 1894 tells Everard that he is dealing with the time travel issues of that year but does not mention any business concerning the 1850-2000 period as a whole. This makes me think that Mainwethering's London office of the Time Patrol is a local office, not milieu HQ, even though that HQ is also located in London, 1890-1910.

Mainwethering's letter sent by message shuttle from June 25, 1894, to Everard in New York, September 6, 1954, mentions four items of current business:

the Addleton affair about which Everard had contacted Mainwethering (as, we learn, have other Patrol members in 1923 and 1960);
an assassination attempt on Queen Victoria;
the Balkan question;
the opium trade with China.

We are not told why either the Balkans or opium concern the Patrol. The assassination attempt is by a German who stole a time machine in 1917. The Addleton affair "'...has gotten into a famous piece of literature...'" (p. 22) (This phrase is attributed to Mainwethering who, however, would not have said, "...gotten...'") The work of literature mentions the singular contents of an ancient British barrow. The London Times of June 25, 1894, and several days following, reports that an amateur archaeologist who opened a surprisingly well preserved chest found in the barrow was killed by a "deadly emanation" from the chest which contained ingots of an unknown metal. The Patrol infers artificial radioactivity left by an unauthorized time traveler.

Everard displays a lack of understanding of time travel theory:

"'Look here...this business may be quite harmless. In fact, since we're here now, it must have been harmless. Eh?'" (p. 23)

If an unauthorized time traveler originating in the current timeline intends to "change the past" in post-Roman Britain, then Everard, while remaining in the original timeline, will continue to exist in a timeline with the familiar and unchanged history of post-Roman Britain. However, if he travels to a time earlier than the date of that British barrow, then comes forward to 1954 or even just to 1894, then he may well find himself in an alternative timeline. It is this that the Patrol has been set up to prevent. If this could never happen, then there would be no need for the Patrol.

Mainwethering partly says this and partly becomes incoherent:

"'As of now...But consider. You two gentlemen go back to Jutish times and find the marauder. But you fail. Perhaps he shoots you before you can shoot him; perhaps he waylays those we send after you. Then he goes on to establish an industrial revolution or whatever he's after. History changes. You being back there before the change-point, still exist...if only as cadavers...but we up here have never been. This conversation never took place.'" (ibid.)

It makes perfect sense to say that there may be another timeline in which "'...we up here have never been. This conversation never took place.'" But it makes no sense whatsoever to say that we who are here now may not be here now or that this conversation that we are having now may not be taking place now. If Time Patrollers stay where/when they are, then they cannot be affected by any causality violation at an earlier date but, if they want to be able to travel into the past and return to the home era from which they had departed, then they must prevent causality violations.