The Planiverse: Computer Contact with a Two-Dimensional World | Hacker News Reader

The Planiverse: Computer Contact with a Two-Dimensional World

cs.stanford.edu

44 pointsbmc750523 comments

I found this book browsing through a cousin's bookshelf as an early teenager, and thereafter it left a lasting impression on me. The idea of a bidirectional communication link with a two-dimensional world and its strangely endearing inhabitants stuck with me ever since, and subconsciously I believe, influenced me to study computer science. I know previous authors have explored similar themes, but the idea and its execution are so carefully and creatively illustrated. What's fascinating is how many of those ideas are now being realized with cellular automata, computer games, and thinking machines.

Same here. The books "The Boy Who Reversed Himself" by William Sleator, and "The Holographic Universe" by Michael Talbot, were the 4D pieces in my adolescent dimensional obsession.

GPT I want to say "isn't that just flatland" but in a nicer way.

It's interesting to read about a two-dimensional world and its inhabitants in The Planiverse. However, it does remind me of Flatland, which also explored the concept of a two-dimensional world. Regardless, it's still a fascinating and thought-provoking read.

The Planiverse is explicitly inspired by Flatland: https://cs.stanford.edu/people/eroberts/courses/soco/project...

Flatland leaves out a lot of details of physics, anatomy, and general science. Everyone is just geometric shapes floating in an endless plain. Planiverse attempts to envision a 2D world with gravity, a food chain, and digressions on the unpleasant reality of being a creature whose digestive system only has a single orifice due to the topological restrictions of their reality.

That last point is quite interesting. I'm having some trouble extrapolating that up into higher dimensions, identifying what limits of the human body would be eliminated by a fourth spatial dimension.

Edit: For some reason using a whole comment to say this got me muted from commenting at all, so I'll put it in an edit: Damn, that shoelace thing is really cool.

You couldn’t tie your shoelaces in 4D because the laces would just slip around each other.

Aren’t some organic molecules effectively knots? Though I imagine there are plenty of alternatives.

You can't knot 1-dimensional curves in 4-dimensions, but you can knot 2-dimensional surfaces.

Therefore, a 5D being ties their shoes with 3D universes.

New twist on the simulation argument: we're living in the shoelaces of someone's high-tech shoes.

A 6D being even! We live from aglet to aglet.

> I'm having some trouble extrapolating that up into higher dimensions, identifying what limits of the human body would be eliminated by a fourth spatial dimension.

That's precisely why Flatland and the Planiverse are such interesting books. Making the step from 2D observing from 3D gives you a little bit of an intuition of how a 4D being would look at us as well as to how a 3D being would look at a 4D one.

IIRC, Rudy Rucker’s Realware had some interesting stuff happening in higher dimensional spaces with humans kidnapped by high-d beings. As all his books, a very fun read.

My favorite was 'The hacker and the ants'.

Dewdney even wrote the introduction to a recent edition of Flatland. He definitely acknowledges the influence.

I don't quite understand the last point, couldn't the gut still twist around and lead to a lower orifice in 2D?

If a 2d creature has two orifices, then it's bisected. The two parts of it's body can't be connected without interrupting the digestive tract.

It's like saying of us 3d creatures: "the butt doesn't have to be connected to the head, does it?"

Oh, that makes sense, thanks!

It's been a long time since I read this book; am I misremembering? I thought they had a butt, but their digestive tract was filled with interlocking pieces that unzipped in waves to let food through? If that was true, I'm not sure how nerve signals would get between their two halves. Perhaps their brains and minds were just good at being split in half every now and then. Maybe they had to sleep to digest. Maybe I'm forgetting that, too. It would also be unsettling to know that your gut was the only thing holding your body in one piece.

as long as some number of teeth were always sufficiently closed you could just have parallel/redundant communication channels using the teeth and never entirely break contact.

Good point; the higher level layers of the brain wouldn't even need to know that there was ever a disconnection. Although it would all still require neural connections that could be physically broken regularly. And we thought USB was picky...

I distinctly recall a dinner scene where, after eating, everyone kind of hung out chatting for a bit, then used dedicated bowls to discretely hork up the undigested remnants.

I seem to recall something about "zippers" at a cellular level? It's been a while and my copy is long gone.

This is a great book which very thoroughly explores a 2D universe. In addition to the biological designs it includes tech like steam engines, aeroplanes, rockets, space stations, and multistorey buildings.

Much recommended for the ideas and the story.

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