What is the highest range for mental abilities of mentalists and of Gaia in the Foundation universe? I'd like an order of magnitude, because for all I know it could be anything from a few ten meters to astronomically huge distances.
In particular, to influence people on a planet, does the Second Foundation have to send agents to that particular planet? To the same solar system? Or can it do that from much farther?
The answer might differ depending on who you take:
early mentalists like Wanda Seldon and her group, precocious mentalists like Vara Liso, trained mentalists like the Second Foundation agents hundreds of years later, Daneel, the Mule, Gaia.
If possible, I'd like an answer for as many of these as possible.
One indication that the abilities have a high range is the plans for Galaxia. Presumably such a galaxy-wide organism is possible only if their members can communicate to interstellar distances.
Here's a list of the books to consider, possibly incomplete, with mentalists mentioned in them:
- Robots of dawn (Giskard)
- Robots and empire (Giskard)
- Prelude to the Foundation (Daneel)
- Forward the Foundation (Raych, Wanda Seldon, Settin Palver)
- Greg Bear's Foundation and Chaos (Daneel, Vara Liso, Klia Asgar, and others)
- Dabid Brin's Foundation's Triumph
- Second Foundation (Second Foundation agents, the Mule)
- Foundation's Edge (Second Foundation agents, Gaia)
- Foundation and Earth (Gaia)
Here are the works that I think should not be considered, but your opinion may differ:
- Pebble in the Sky