Book I read a few years ago. Main plot points:

-Time travel had been attempted by a research group, but was unsuccessful. They threw out the device and the janitor, who "just happened to be a quantum physicist" (I remember this line clearly from the book).

-The janitor started a group to go back in time and steal items for him. I only remember one specific item: a flag from 2076. I think that the group was composed of children and they may have eventually rebelled against him.

-People who stayed in the past for too long suffer from "time sickness"

Book I read a few years ago. Main plot points:

• Time travel had been attempted by a research group, but was unsuccessful. They threw out the device and the janitor, who "just happened to be a quantum physicist" (I remember this line clearly from the book).

• The janitor started a group to go back in time and steal items for him. I only remember one specific item: a flag from 2076. I think that the group was composed of children and they may have eventually rebelled against him.

• People who stayed in the past for too long suffer from "time sickness"