3 Days, 9 Months, 27 Years (The Time Traveler's Passport)

by John Scalzi

It is psychologically important, when traveling through time, to have another human be the last and first thing you see.

The point is that our present cannot and will not be changed by time travelers—they will change a reality we are not connected to in any way, except at the specific retrieval intervals.

Once the client returned, the connection to the other reality was severed, and no further information would pass between there and here.

The thing that made time travel useless for historians is what made it profitable for tourism: Introducing information from one reality to another alters the second reality irrevocably.

The butterfly effect is correct, but the butterfly is in another reality entirely.

“History” stops being accurate the moment you observe it.

I know now, however, that whatever reality I am in, in the end, I carry only myself into it. Realities change, and I am the constant.