# ­xkcd thread **URL:** \ **Category:** Cafe Society\ **Tags:** comic-strips\ **Created:** [May 28, 2020, 12:57am UTC](https://boards.straightdope.com/t/xkcd-thread/854574 "2020-05-28T00:57:03Z")\ **Posts on this page:** 20\ **Page:** 310
**Author:** ![dtilque](https://avatars.discourse-cdn.com/v4/letter/d/d6d6ee/32.png) [@dtilque](https://boards.straightdope.com/u/dtilque)\ **Post date:** [July 24, 2026, 11:21pm UTC](https://boards.straightdope.com/t/xkcd-thread/854574/6183 "2026-07-24T23:21:31Z")
> **[Recursive Trucker's Hitch](https://xkcd.com/3276/)** [![](https://imgs.xkcd.com/comics/recursive_truckers_hitch.png) ](https://imgs.xkcd.com/comics/recursive_truckers_hitch.png) “As if the americium smoke detector incident wasn’t enough, now nuclear regulators have ANOTHER reason to worry about the Boy Scouts.” ---
**Author:** ![Wheelz](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/wheelz/32/5718_2.png) [@Wheelz](https://boards.straightdope.com/u/Wheelz)\ **Post date:** [July 24, 2026, 11:35pm UTC](https://boards.straightdope.com/t/xkcd-thread/854574/6184 "2026-07-24T23:35:57Z")
Every now and then there’s an XKCD that I haven’t the slightest idea what even a single element of it means. This is one such example. ---
**Author:** ![markn\_1](https://avatars.discourse-cdn.com/v4/letter/m/f9ae1b/32.png) [@markn\_1](https://boards.straightdope.com/u/markn_1)\ **Post date:** [July 25, 2026, 12:21am UTC](https://boards.straightdope.com/t/xkcd-thread/854574/6185 "2026-07-25T00:21:56Z")
The Truckers Hitch is a knot that acts kind of like a block and tackle without requiring an actual block and tackle. It provides a theoretical 3-to-1 mechanical advantage using idealized frictionless rope. In real life the advantage is more like 2-to-1 or less because of friction. Munroe has designed a multi-level knot that would theoretically produce an enormous mechanical advantage, like a block and tackle with many pulleys. In reality, the friction of the rope against itself would probably make the knot totally immovable after a couple of levels. > **[Autolocking Trucker's Hitch](https://knots3d.com/en/autolocking-truckers-hitch-knot)** > > Autolocking Trucker's Hitch: Mechanical advantage system for securing loads using a block-and-tackle mechanism. ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [July 25, 2026, 1:32am UTC](https://boards.straightdope.com/t/xkcd-thread/854574/6186 "2026-07-25T01:32:02Z")
I suspect that it wasn’t his invention, but that it usually only has two or three levels of recursion. Also, if I’m following that diagram correctly, the maximum force would be limited to a few times the ultimate tensile strength of the cord, before the top one broke. ---
**Author:** ![Lumpy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lumpy/32/446_2.png) [@Lumpy](https://boards.straightdope.com/u/Lumpy)\ **Post date:** [July 25, 2026, 1:50am UTC](https://boards.straightdope.com/t/xkcd-thread/854574/6187 "2026-07-25T01:50:08Z")
It’s like those multiple layer gear boxes that in theory could produce enough torque to crush matter into neutronium; of course the material limits could never come close to that. ---
**Author:** ![DesertDog](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/desertdog/32/11503_2.png) [@DesertDog](https://boards.straightdope.com/u/DesertDog)\ **Post date:** [July 25, 2026, 2:00am UTC](https://boards.straightdope.com/t/xkcd-thread/854574/6188 "2026-07-25T02:00:18Z")
“Well, the invention works. Now it’s up to the materials engineers to figure out how to make it.” ---
**Author:** ![Peter\_Morris](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/peter_morris/32/359_2.png) [@Peter\_Morris](https://boards.straightdope.com/u/Peter_Morris)\ **Post date:** [July 25, 2026, 7:44am UTC](https://boards.straightdope.com/t/xkcd-thread/854574/6189 "2026-07-25T07:44:54Z")
Okay, so a trucker’s hitch is sort of like a pulley made of rope. Got it. Why is it funny? ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [July 25, 2026, 12:56pm UTC](https://boards.straightdope.com/t/xkcd-thread/854574/6190 "2026-07-25T12:56:15Z")
Same as many other XKCDs, because he’s taking something normal to a ludicrous extreme. A 3-fold trucker’s hitch that gives you a 43:1 mechanical advantage might be useful sometimes. A 50-fold one to crush a fusion pellet isn’t. ---
**Author:** ![Andy\_L](https://avatars.discourse-cdn.com/v4/letter/a/c67d28/32.png) [@Andy\_L](https://boards.straightdope.com/u/Andy_L)\ **Post date:** [July 27, 2026, 2:02am UTC](https://boards.straightdope.com/t/xkcd-thread/854574/6191 "2026-07-27T02:02:58Z")
It’s sometimes represented as a sword in an anvil, with the anvil embedded in stone. This might symbolize a sword made of meteoric steel, which is ridiculously unlikely but would also be wicked awesome ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [July 27, 2026, 3:03am UTC](https://boards.straightdope.com/t/xkcd-thread/854574/6192 "2026-07-27T03:03:44Z")
Of note, the Pratchett knightly sword is forged of meteoric steel. Because of course when he was knighted, he decided, first, that that meant that he needed a sword, second, that he ought to make it for himself, and third, that he ought to make it the right way. ---
**Author:** ![Lumpy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lumpy/32/446_2.png) [@Lumpy](https://boards.straightdope.com/u/Lumpy)\ **Post date:** [July 27, 2026, 3:17am UTC](https://boards.straightdope.com/t/xkcd-thread/854574/6193 "2026-07-27T03:17:35Z")
But did he finish by chopping the anvil it was made on in half? ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [July 27, 2026, 11:05pm UTC](https://boards.straightdope.com/t/xkcd-thread/854574/6194 "2026-07-27T23:05:16Z")
> **[Forth](https://xkcd.com/3277/)** [![](https://imgs.xkcd.com/comics/forth.png) ](https://imgs.xkcd.com/comics/forth.png) “I NOTATION POLISH REVERSE ❤” ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [July 27, 2026, 11:05pm UTC](https://boards.straightdope.com/t/xkcd-thread/854574/6195 "2026-07-27T23:05:52Z")
So is ❤ a binary or quarnary operator? ---
**Author:** ![abcdefghij](https://avatars.discourse-cdn.com/v4/letter/a/43a26b/32.png) [@abcdefghij](https://boards.straightdope.com/u/abcdefghij)\ **Post date:** [July 28, 2026, 12:02am UTC](https://boards.straightdope.com/t/xkcd-thread/854574/6196 "2026-07-28T00:02:24Z")
I don’t judge ---
**Author:** ![LSLGuy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lslguy/32/5813_2.png) [@LSLGuy](https://boards.straightdope.com/u/LSLGuy)\ **Post date:** [July 28, 2026, 1:49pm UTC](https://boards.straightdope.com/t/xkcd-thread/854574/6197 "2026-07-28T13:49:08Z")
This makes me really want to post some APL. Which I was once good at. But I’m not quite up to making a clever enough English statement out of it. Yet. The day is still young. ---
**Author:** ![thorny\_locust](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/thorny_locust/32/431_2.png) [@thorny\_locust](https://boards.straightdope.com/u/thorny_locust)\ **Post date:** [July 28, 2026, 2:16pm UTC](https://boards.straightdope.com/t/xkcd-thread/854574/6198 "2026-07-28T14:16:08Z")
I don’t get it. ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [July 28, 2026, 2:42pm UTC](https://boards.straightdope.com/t/xkcd-thread/854574/6199 "2026-07-28T14:42:46Z")
We usually write operators (at least, binary operators, which take two inputs and which are the only kind most folks encounter regularly) in between their two inputs, like “2 + 2”. But in the Forth programming language, and in Reverse Polish Notation calculators, the operator goes at the end, and operates on the things before it. One benefit of this is that an operator can operate on any number of inputs, as long as it knows how many inputs it’s supposed to take (in fact, a bare number can itself be considered as an operator, that takes zero inputs). So in RPN, you would instead type “2 [enter] 2 +” (the [enter] is needed between numbers, so you can tell the difference between a pair of 2s and the number twenty-two, but can be skipped with most inputs). So for the bumper sticker, you would ordinarily write something like “I ❤ Fortran”, but since, in Forth, the operator goes at the end, it’s instead “I Forth ❤”. Here, the operator is implied to be a binary operator, with two inputs, that’s connecting the “I” and the “Forth”. But in the mouseover text, it looks like the ❤ is taking four inputs,“I”, “Notation”, “Polish”, and “Reverse”. ---
**Author:** ![thorny\_locust](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/thorny_locust/32/431_2.png) [@thorny\_locust](https://boards.straightdope.com/u/thorny_locust)\ **Post date:** [July 28, 2026, 2:57pm UTC](https://boards.straightdope.com/t/xkcd-thread/854574/6200 "2026-07-28T14:57:34Z")
> [@Chronos](#): > > in the Forth programming language, and in Reverse Polish Notation calculators Thanks. I figured something like that was going on — that is, that it was some sort of programmer joke — but had no idea what. ---
**Author:** ![puzzlegal](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/puzzlegal/32/3827_2.png) [@puzzlegal](https://boards.straightdope.com/u/puzzlegal)\ **Post date:** [July 28, 2026, 3:05pm UTC](https://boards.straightdope.com/t/xkcd-thread/854574/6201 "2026-07-28T15:05:44Z")
Thanks! I’m not familiar with Forth. I do like reverse polish notation, though, and still use it on my phone calculator. ---
**Author:** ![Mollie\_Magill](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mollie_magill/32/20882_2.png) [@Mollie\_Magill](https://boards.straightdope.com/u/Mollie_Magill)\ **Post date:** [July 28, 2026, 3:08pm UTC](https://boards.straightdope.com/t/xkcd-thread/854574/6202 "2026-07-28T15:08:00Z")
Thank you. I’d not heard of the Forth language. I do remember my HP-48s with the reverse Polish notation, though. I had programmed it to play blues riffs. [Previous page](https://boards.straightdope.com/t/xkcd-thread/854574.md?page=309) [Next page](https://boards.straightdope.com/t/xkcd-thread/854574.md?page=311)