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:

  • Nemesis
  • Pebble in the Sky

3 Answers 3


The effects of distance on mentalic ability are not clear. Stor Gendibal, a Second Foundationer, thinks in Foundation's Edge:

It was well known that the mentalic field did not obey the inverse-square law. It did not grow stronger precisely as the square of the extent to which distance between emitter and receiver lessened. It differed in this way from the electromagnetic and the gravitational fields. Still, although mentalic fields varied less with distance than the various physical fields did, it was not altogether insensitive to distance, either. The response of Novi’s mind should show a detectable increase as the warship approached - some increase.
(How was it that no Second Foundationer in five centuries - from Hari Seldon on - had ever thought of working out a mathematical relationship between mentalic intensity and distance? This shrugging off of physics must and would stop, Gendibal silently vowed.)

A little later,

Gendibal narrowed the mentalic field controlled by his mind. It intensified and leaped across the gap between the ships at the speed of light. (The two ships were close enough to make hyperspatial contact - with its inevitable loss of precision - unnecessary.)

This suggests that mentalic abilities are ordinarily limited by light-speed, but can also somehow operate through hyperspace. However, we do not generally see characters reading and manipulating minds at vast distances. Mentalics, including the Mule, often have to travel somewhere in order to act. For example, we see the Mule dampening the morale of planets he is ready to conquer, but he doesn't do that from afar. Preem Palver has to travel in order to combat the Mule, Stor Gendibal also has to be physically present to investigate, and the Second Foundation relies on agents in-place rather than scanning minds from Trantor.

Ordinary human mentalics can communicate superluminally, and can act over large distances. For Gendibal,

  • He speaks telepathically with Compor over a distance of "hundreds of parsecs", and Compor is a very weak mentalic. It's not stated whether that applies for other mentalic abilities, or where the other party isn't themselves a willing mentalic.
  • He can handle multiple minds at a distance of about half a million kilometres, or a bit more than a light-second.
  • He can detect Gaia's mentalic field from a hundred million kilometres. (That's stated to be more due to Gaia's power than his own detection skill.)

He is a strong mentalic but not treated as exceptionally strong by the others, so we can assume other senior Second Foundation members are at a similar level. I do not think we see any human characters altering or reading minds at hyperspatial distances. The second quoted passage above seems to imply that it's possible, but perhaps requiring great power to be able to overcome the loss of precision.

In Foundation and Earth, Daneel laments that he has "an even more rapidly declining ability to test and influence minds at hyperspatial distances", after describing how from Earth's moon he has subtly influenced events as far away as Comporellon. Comporellon is Epsilon Eridani, which is over ten light years from Earth. He is able to do this partly by virtue of his contact with Gaia (which is much further away) and Bliss is continually part of Gaia in her travels. So if you have the combined mentalic power of an entire planet, plus unknown robot-technology, you can do it. (Bliss herself still needed to be present in this case, but I think Daneel's statement implies that he could do it himself with great effort.)


There seems to be no mention of a superluminal mechanism for mentalism, so there would be a constraint on the time delay. this would be contradicted by any mention of nearly instantaneous communication between planets indifferent star systems, and I know of none such. This would place a practical limit on the range for interactions relevant to the mentalist's lifetime.

  • The Foundation novels do feature faster-than-light travel, introduced on p. 4 of "Foundation" which says: "He had steeled himself just a little for the Jump through hyperspace, a phenomenon one did not experience in simple interplanetary trips. The Jump remained, and would probably remain forever, the only practical method of travelling between the stars ... Through hyperspace, that unimaginable region that was neither space nor time, matter nor energy, something nor nothing, one could traverse the length of the Galaxy in the interval between two neighboring instants of time."
    – Hypnosifl
    Commented Mar 9, 2014 at 15:33
  • Also, searching a little more I see Asimov's books also mention a "hyperwave relay" system which allows FTL communication without travel, see for example p. 128 of "Foundation" (end of ch. 6). In "Second Foundation" this is often referred to as just a "hyper-relay", you can click the cover at amazon.com/Second-Foundation-Novels-Isaac-Asimov/dp/0553293362 and then type "relay" in the "search inside the book" box to find a bunch of examples.
    – Hypnosifl
    Commented Mar 9, 2014 at 15:45
  • I believe those relays were man made. I have not seen any reference to mentalism being relayed through them. Commented Mar 9, 2014 at 18:03
  • Well, I thought when you said that you don't know any mention of "nearly instantaneous communication between planets" you were talking generally, not just about psychic powers. If the laws of nature of this universe allow for FTL communication in general, then there's no reason to take it as a default assumption that telepathy is limited by light speed, we should just say that we haven't found a reference in the text that settles the question one way or another. Though I think the OP's mention of "Galaxia", a unified group mind spanning the galaxy, tends to favor FTL telepathy.
    – Hypnosifl
    Commented Mar 9, 2014 at 18:53
  • @Hypnosifl - I agree that the reference to "Galaxia" likely implies FTL telepathy. The only other way it would be possible is if "Galaxia" were to "metabolize" VERY slowly, which I do not think was implied by Asimov. Commented Mar 9, 2014 at 20:11

In at least some cases, mental abilities can span interstellar distances.

In David Brin's Foundation's Triumph, Dors and Lodovik can simultanously detect the presense of

the positronic emotional control satellite devices orbitting the fifty former spacer worlds

when they get near Earth.

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