6 ms·

Impossible Figures Library

onion2k 6y ago
I'm struggling to understand why the illustration at the bottom left of https://im-possible.info/english/library/grey/grey4.html https://im-possible.info/english/library/grey/grey4.html is impossible. If you don't assume the two horizontal bars are parallel, and the top one is farther back than the bottom one, it make seems to make sense. Eg it has a side profile of; ---- ---------------- ----
- coding_lobster 6y ago
  I guess it's because the bottom and top bar look like their edges are actually touching which should be impossible with the middle bar going between them without it being squished.
- francasso 6y ago
  I don't think your idea would work in an ortho projection (like the one in the drawing). If the two horizontal bars were separated vertically you would have to see a space between them instead of the them sharing an edge. You idea should work if there is perspective distortion involved and the top bar is closer to the viewer and is also longer than the other.
- andyjohnson0 6y ago
  A agree, and I just reproduced it physically using three rectangular objects that were to hand on my desk. Presumably the impossibility is meant to be that the edges of the two parallel bars are actually touching, rather than just being aligned in the angle of view. But it is certainly possible to reproduce this physically.
- pfortuny 6y ago
  The "bottom" and "top" pieces have the same length (transversal in your projection), as the 3d figure shows. But if you try to place the pieces so that their edges match on a projection, then they cannot start and end at the same point (one is "nearer" the camera than the other).
- jwilk 6y ago
  I was able to recreate it in FreeCAD: https://i.imgur.com/atOSXbc.gif https://i.imgur.com/atOSXbc.gif
082349872349872 6y ago
I wonder what the text equivalent would be. Are there sentences which are locally consistent[1] but globally impossible? (the question is on my mind because earlier on HN I'd had a nice convo about a folk song embedded in a protest song in which the quoted verse worked nearly as well as polish under a functor as in the original ukrainian. https://news.ycombinator.com/item?id=24101696 https://news.ycombinator.com/item?id=24101696 ) [1] on a longer scale than "colourless green ideas sleep furiously", of course.
- tempodox 6y ago
  Paradoxes, like: This sentence is a lie.
- theemathas 6y ago
  Garden-path sentences. Or comparative illusions. https://en.wikipedia.org/wiki/Garden-path_sentence https://en.wikipedia.org/wiki/Garden-path_sentence https://en.wikipedia.org/wiki/Comparative_illusion https://en.wikipedia.org/wiki/Comparative_illusion
  - 082349872349872 6y ago
    ขอบคุณ! The garden-path admits of a consistent, yet initially unpredicted reading, while the comparative illusion is exactly what I'd been groping for: locally cromulent but globally uffish.
- eternalban 6y ago
  First you need to map geometric concepts to language. What is grammar, what is syntax? (I propose that 'syntax' is 'local coherence', and grammar is 'global coherence'.) And the trick of these figures is using symmetry to fool the brain into creating imaginary 'grammatical structure' that simply are not there. What is important to note is at symmetric axis, graphical duals are present which are syntactically correct -- a beam intersecting a plane for example -- but are no longer semantically equivalent. So probably, homonyms will be required liberally.
- thaumasiotes 6y ago
matsemann 6y ago
I like these. Some of them are even non-obviously impossible. They may pass at first glance, but then one sees why it shouldn't work. I recently posted my figures [0] here. It's also a kind of impossible figures, however they are actually printable in real life but still tricks the mind. [0]: https://github.com/Matsemann/impossible-objects https://github.com/Matsemann/impossible-objects
mmazing 6y ago
It cracks me up that I'm getting tons of ads for 3D printing on a website for impossible objects.
- 082349872349872 6y ago
  Then I'll suggest https://www.kleinbottle.com https://www.kleinbottle.com "Glass Klein Bottles for sale - inquire within"
  - eternalban 6y ago
    You could be the future of advertising..

I'm struggling to understand why the illustration at the bottom left of https://im-possible.info/english/library/grey/grey4.html https://im-possible.info/english/library/grey/grey4.html is impossible. If you don't assume the two horizontal bars are parallel, and the top one is farther back than the bottom one, it make seems to make sense. Eg it has a side profile of; ---- ---------------- ----

coding_lobster 6y ago
I guess it's because the bottom and top bar look like their edges are actually touching which should be impossible with the middle bar going between them without it being squished.
francasso 6y ago
I don't think your idea would work in an ortho projection (like the one in the drawing). If the two horizontal bars were separated vertically you would have to see a space between them instead of the them sharing an edge. You idea should work if there is perspective distortion involved and the top bar is closer to the viewer and is also longer than the other.
andyjohnson0 6y ago
A agree, and I just reproduced it physically using three rectangular objects that were to hand on my desk. Presumably the impossibility is meant to be that the edges of the two parallel bars are actually touching, rather than just being aligned in the angle of view. But it is certainly possible to reproduce this physically.
pfortuny 6y ago
The "bottom" and "top" pieces have the same length (transversal in your projection), as the 3d figure shows. But if you try to place the pieces so that their edges match on a projection, then they cannot start and end at the same point (one is "nearer" the camera than the other).
jwilk 6y ago
I was able to recreate it in FreeCAD: https://i.imgur.com/atOSXbc.gif https://i.imgur.com/atOSXbc.gif

082349872349872 6y ago

I wonder what the text equivalent would be. Are there sentences which are locally consistent[1] but globally impossible? (the question is on my mind because earlier on HN I'd had a nice convo about a folk song embedded in a protest song in which the quoted verse worked nearly as well as polish under a functor as in the original ukrainian. https://news.ycombinator.com/item?id=24101696 https://news.ycombinator.com/item?id=24101696 ) [1] on a longer scale than "colourless green ideas sleep furiously", of course.

tempodox 6y ago
Paradoxes, like: This sentence is a lie.
theemathas 6y ago
Garden-path sentences. Or comparative illusions. https://en.wikipedia.org/wiki/Garden-path_sentence https://en.wikipedia.org/wiki/Garden-path_sentence https://en.wikipedia.org/wiki/Comparative_illusion https://en.wikipedia.org/wiki/Comparative_illusion
- 082349872349872 6y ago
  ขอบคุณ! The garden-path admits of a consistent, yet initially unpredicted reading, while the comparative illusion is exactly what I'd been groping for: locally cromulent but globally uffish.
eternalban 6y ago
First you need to map geometric concepts to language. What is grammar, what is syntax? (I propose that 'syntax' is 'local coherence', and grammar is 'global coherence'.) And the trick of these figures is using symmetry to fool the brain into creating imaginary 'grammatical structure' that simply are not there. What is important to note is at symmetric axis, graphical duals are present which are syntactically correct -- a beam intersecting a plane for example -- but are no longer semantically equivalent. So probably, homonyms will be required liberally.
thaumasiotes 6y ago

matsemann 6y ago

I like these. Some of them are even non-obviously impossible. They may pass at first glance, but then one sees why it shouldn't work. I recently posted my figures [0] here. It's also a kind of impossible figures, however they are actually printable in real life but still tricks the mind. [0]: https://github.com/Matsemann/impossible-objects https://github.com/Matsemann/impossible-objects

mmazing 6y ago

It cracks me up that I'm getting tons of ads for 3D printing on a website for impossible objects.

082349872349872 6y ago
Then I'll suggest https://www.kleinbottle.com https://www.kleinbottle.com "Glass Klein Bottles for sale - inquire within"
- eternalban 6y ago
  You could be the future of advertising..