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- Hacker News
- A lovely little podcast on paper physics for origami.by zeristor
- Shameless plug - https://foldmation.com
Big backlog of folds to approve seems like it's ignored. I'm in the middle of fixing some rendering issues hence I haven't approve them yet. Rendering fixes and fold approvals should be up in a few weeks.
by fuzzythinker - And why does it sink. Its basically squished wood!by yread
- Because the air is squished out I suppose
- because the fibers are denser than wood and hydrophilic - so the pockets between the fibers fill with water that displaces the air.
Air pockets become water pockets = neutral.
Fibers denser than water = sink.
by flybrand - I really can't imagine getting paper to sink any more easily than wood?by OJFord
- This is exactly the sort of hard-hitting journalism that makes me proud to pay my TV licence.by leebeef
- It’s always hard to tell whether a comment like this is supportive or sarcastic so this is either me agreeing or disagreeing with you…
For me this kind of simple, straightforward, educational content is part of the reason I’m proud to pay my TV licence.
by tomalpha - Unless I'm missing a transcript somewhere, this is missing an [audio] tag.by arijun
- Nice old video about this: https://www.youtube.com/watch?v=EKEavnS10HIby borutz
- The Mythbusters proved you can fold it up all the way to 11: https://www.youtube.com/watch?v=65Qzc3_NtGsby aequitas
- It was this paper folding video (and the guy's unapologetic Finnish accent) that launched Hydraulic Press Channel to fame.by sampo
- It has a lot of air gaps within its fibers.
We know that Solids CANNOT be compressed. So what's actually being folded is the air gaps.
Which is why you can't easily fold a piece of tungsten. It has less air gaps.
by Peterz_shu - Pretty sure the material's innate stiffness plays a role there, too.
Metallic film folds quite nicely.
by IAmBroom - But you can fold aluminum foil just fine? That certainly doesn't have "a lot of air gaps within its fiber"by gruez
- Oh no! woe is me, they don't highlight my absolutely, ridiculously favourite fact/curiosity about a sheet of smooth paper:
If you fold it clean, the crease is a straight line. In fact I don't know of any other good way of obtaining a straight edge from scratch quickly, meaning without transporting one existing straight edge to another (*).
I remember spending a lot of enamored time coming up with different geometrical proofs of this fact. Perhaps the only time I have come close to jumping out of the proverbial bath tub.
The underlying reason is that paper does not stretch (**) (but, paradoxically, it does bend fine. It's a paradox because bending needs stretching).
I have to restrain myself from grabbing strangers off the streets to ask -- how cool is that.
Three other demonstrations that never fail to nerd-snipe me like this are Dirac's belt trick, that straight woven cloth rips usually at 90 degrees, and the working of a teeny tiny metacircular interpreter.
(*) Rope stretching is a close competitor, but the tension needs to be really really high and it is difficult to run a pencil along it to mark a straight line, lest you distort the st. line.
(**) of course, it does, but a tiny amount.
Coming back to straight line folds, this property holds beyond just Euclidean space, it holds for Riemannian geometry and probably for any continuous metric space.
by srean - > If you fold it clean, the crease is a straight line. In fact I don't know of any other good way of obtaining a straight edge from scratch quickly, meaning without transporting one existing straight edge to another.
It would be interesting to see how progressively larger pieces of paper handle this. A roll of masking paper would be the easiest way to test.
by oidar - Paper is thin so the stretching needed to bend it is minimalby mjanx123
- One thing I find interesting about paper is that wetting and drying it turns it uneven. Even when drying it under a press.
And then another ridiculous process not involving paper, but super cool nonetheless is creating a flat surface by grinding 3 not-flat objects against each other in round-robin manner.
by foobarian - If you want to use a rope to get a straight line, your best bet is to turn the rope itself into the pencil. Coat it in chalk or other powder, then put it under tension and snap it on to the desired surfaceby wongarsu
- The shortest distance between two points is a straight line?
A sheet of paper approximates a Cartesian plane probably more closely than most things we can fold
Therefore a fold will always be in line with the theoretical 2D plane and thus will be the shortest (straight) line.
by rusk - > The underlying reason is that paper does not stretch
I don't think that's sufficient--tinfoil doesn't stretch, but it doesn't fold nearly as neatly as paper.
by arijun - I'm a fan of tearing paper along a crease rather than cutting it for this reason, since the tear is straight and using scissors will invariably be all over the place.by saagarjha
- And once you have created such a straight line, you can fold the paper again such that the first crease lines up on both sides of the new crease, and then you have a right angle.