I am not concerned about time travellers, I am sure they have good manners and don't want to upset the temporo-equilibrium.
Unless of course they are terminators... hmmm... I may have to reconsider.
1. something that is contemplated, devised, or planned; plan; scheme.
2. a large or major undertaking, especially one involving considerable money, personnel, and equipment.
3. a specific task of investigation, especially in scholarship.
4. to propose, contemplate, or plan.
5. to throw, cast, or impel forward or onward.
6. to set forth or calculate (some future thing).
7. to extend or protrude beyond something else.
8. to use one's voice forcefully enough to be heard at a distance, as in a theater.
9. to produce a clear impression of one's thoughts, personality, role, etc.