(Caveat I've only read the first 2 books)

In the Long Earth series it is only described in an off handed manner that people can't step into solid matter. E.g., you can imprison people by placing them in an underground cell, so that they can't step East or West.

But is it ever explained how doing so inhibits the stepping process? As an analogy, is it like a non-stepping person walking into a hard wall, or does it stop them from hitting the wall in the first place?

And/Or bonus question, is stepping only achievable when stepping into a gaseous medium (or vacuum), or can you also step into a liquid?

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    Underwater seems fine; A few minutes later Sally was grasping a brimming mug of coffee as if it were a lifeline. ‘And did you notice? The traveller steps underwater. That’s a new one.’
    – Valorum
    Jun 28, 2020 at 15:43
  • @Valorum Dang! As soon as I saw your comment I remember reading that passage.
    – Peter M
    Jun 28, 2020 at 15:45
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    I only read the first book but I had the impression that the stepping process wasn't described at all. If the whole thing is a handwave, what makes this specific restriction any more of one? Jun 28, 2020 at 15:56
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    @DanielRoseman There are 3 other books that I haven't read that could contain the answer to the handwaving. And I know for a fact that there some things not explained in book #1 that were revealed in book #2
    – Peter M
    Jun 28, 2020 at 16:24

2 Answers 2


While it is never expressly stated in any of the books, I would hazard two guesses. The first is hinted at in the series, mostly in The Long Cosmos. The second is more inference based on the viewed "rules" of stepping, rather than tied to specific statements by any in-universe experts:

1:In The Long Cosmos they discuss that the act of stepping is, fundamentally, an act of Imagination. A human/sentient needs to be able to visualize another place/the possibility of another world, and therefor is able to step. Though it's not as clear-cut as all that, because there's a lady who lives on one of the low earths, but can only see/hear the neighboring low earth. (I don't have the book handy so may be mis-remembering the earth number) Essentially she's blind and deaf on Earth West 22, but can hear and see her grandkids playing on Earth West 21. So it could be that if a human could IMAGINE themselves stepping into a solid, they would. But nobody can bring themselves to believe in that hard enough to actually DO it, because they'd appear completely buried, without air, and with no way to get out. Likewise when they're stepping into another long earth and blocked by, say, a tree, they don't step because they aren't believing they'll step into a tree, they're believing they're stepping into an open place and thus the step doesn't work.

2: This one doesn't have any book dialog supporting the notion like the other, but it's another solution that makes sense to me. The steppers atoms need to displace the atoms previously occupying the space. Since solids have atoms that are tightly bonded together, they cannot be "pushed aside" as easily as liquid or gas. Though the "push" still happens, so for instance things that are solid but flexible, like grass, might be bent out of Stepper's way. This has the advantage of being a workable solution to "Why can people step at all when grass is everywhere and never going to be the same height." There obviously is some upper limit to the "force" exerted by a stepper though, as you get "stepped into grassland/snow" all the time, but "filling your living room with furniture" is stated to be an adequate defense against Steppers appearing in your house.

There's also no real reason why these two things can't be taken together, lord knows that's how I've viewed stepping ever since I finished the series!

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    You could make this answer better by including quotes from the books to support your point #1.
    – PM 2Ring
    Jul 7, 2020 at 0:54

The mechanism itself is never explained, but the analogy of a wall is used in the first book. When Joshua flees from the Madison police, stepping for the first time without his box he continues across the Long Earth until he encounters something that stops him.

And then he came to a Wall. A place where he couldn't step on, no matter how he walked sideways. He even took a few paces back and kind of ran at it, trying to force his way onward. It didn't hurt, it was like running into a huge upraised palm. But he couldn't go forwards.

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