Edit: Oh boy, wall of text crits for 10k.

His explanation was rather short and somewhat misleading. Maybe they thought a proper explanation would have been too dry or too lengthy to be of any interest for a sufficient number of their viewers.

tl:dr

If all rotor settings are indicated to be correct, a feedback loop within the circuit indicated a subset of correct connections on the plugboard, even if the initially assumed connection turned out to be wrong. It didn't show all connections, but enough to run it through a modified Enigma to determine if it's a false positive or in fact the correct setting. If it was correct, the rest could be done by hand.

----------------------- Long version -----------------------

Apologies in advance. We had to recreate parts of the Bombe as a simulation, but a) it's been a while and b) it was in German. I'll try to explain the concept behind it, hopefully without screwing it up entirely.

The combination of clear message and code snippet (2:25) is called a crib. This can be used to create a graph, wherein letters are the vertices and connections together with their numerical positions are the edges.

For example, at position 1, "A" corresponds to "W". So you'd create an edge between "A" and "W" and mark that edge as "1". At position 4, "B" corresponds to "T", so there's the edge marked as "4". All edges are bidirectional, the transformation at a specific position can go either way.

Once your graph is finished, you check for loops. These are essential. Without loops, you're boned. In this case, one loop can be found at positions 2,3,5 in form of "T->E->Q->T".

Here the Bombe comes into play. It uses scramblers, each combining all three rotors plus reflector of an enigma into one segment. This way, one Enigma setting is functionally equal to a single scrambler.

Now you can use those scramblers to create an electrical circuit that corresponds to your graph -- scrambler = edge. All scramblers are set to the same initial configuration. The first scramber remains at in the inital configuration, while the second and third get configurations in relation to their edge's numerical value. Configuration in this case means the value of their internal three rotors, so there are 26*26*26 possible settings within each scrambler.

It's basically a sequence of three encryptions.

Example: in our little TEQ triangle, the first scrambler (TE, 2) gets a random starting position. The second scrambler (QE, 5) gets turned three notches, the third scrambler (QT, 3) gets turned one notch. The initial configuration might be wrong, but only the relation between the scramblers matters. A wrong result simply tells you to turn all scramblers another notch, until you get it right.

You have a possibly correct setting when the output matches the input. Specifically, a voltage is applied to the wire of letter "T", leading into the first scrambler. And on a test register attached to the last scrambler, the wire of letter "T" should have a voltage on it as well. If the setting is incorrect, a different letter will light up. Similarly, all incorrect inputs for this particular setup will always light up a different letter at the the end, never the same (thanks to the reflector). If output equals input, you're golden. And if several loops are used, all with the same input/output letter, each of their outputs must equal the input.

To reduce the number of false positives, you need as many connected loops within the crib as possible.

So far, that's an Enigma without a plugboard. To account for that, they introduced feedback loops into the circuit. In our small scale case, the output of the third scrambler would be coupled back into the input of the first scrambler. The number of loops determines the number of possible outcomes with each specific setting. All of these are fed back into the first scrambler of each loop.

The plugboard, however, changed the input into the system of rotors. Instead of a "T" in our example, it might be a "Z", if those two letters were connected on the board.

A random hypothesis is made and fed into the machine. If the scramblers are set incorrectly, a different letter comes out at the end of each loop and is in return fed back into the first scramblers. Result: (almost) everything lights up. If you start with a good graph, everything will light up.

-----
A key element for this was the "diagonal board", which represented a) all possible connections on the plugboard and b) the bidirectional nature of those connections (AB = BA). Maybe it can be explained without pictures, but I sure as hell can't, so "a grid of all possible connections between scramblers and letters + forced reciprocity" will have to suffice.
-----

If, however, the setting was correct, a wrong hypothesis for the input connection merely meant that everything except the right connections was lit up.

Let's say the fix point of the loops in our graph is the letter "T". We assume that it's connected to the letter "Z" on the plugboard. A voltage is applied to "Z" on the test register, and thereby inserted into the circuit at the first scrambler. Loop #1 applies voltage to the letter "A" on the test register, #2 lights up "B", #3 lights up "F". These three outputs are now fed back into the first scrambler, so now the scrambler has voltage on ZABF, which in return lights up ZABF+GEK on the test register.
This goes on until everything except "U" is lit up on the test register. That means three things: a) the settings are correct, b) the hypothesis is wrong, c) "T" is connected to "U".

Reasons:
a) if the settings were incorrect, the entire register would be alive
b) if the hypothesis was correct, only the letter "Z" would be alive on the register
c) due to the feedback loop, the only way for the output to be "U" is if the input was also "U", and the reciprocity within the system makes it impossible for any other input to generate the output "U". Since "T" was the fix point for our loops, "T" is connected to "U".

Similarly, if the initial hypothesis is correct, everything on the test register except "U" stays dead.

The diagonal board provides registers for every single letter and allows the user to pick one as a test register. During operation, all the other registers serve as visual representations of the deductions based on the initial hypothesis. So you actually get to see more than just the initial connection, all based on the same concept.

and somebody's playing the sh*t out of some triangles back there, too.

Tags for this video have been changed from 'Pythagora, experiment, squares, triangle, Pythagorean Theorem' to 'Pythagoras, experiment, squares, triangle, Pythagorean Theorem' - edited by xxovercastxx

Tags for this video have been changed from 'Pythagora, experiment, squares, triangle' to 'Pythagora, experiment, squares, triangle, Pythagorean Theorem' - edited by lucky760

I loved Chiang Mai when i was there during the water festival. It was great fun. Plus we smoked opium while on a trek in the golden triangle area.

/Kceaton1 In reply, I must say you should watch Community, it is one of the greatest shows I've ever seen. Every show is a classic, and feels like they are parodying another show or movie in each one, and the character development was amazing. There are some episodes people complained about because of a silly love triangle going on. But that was the genius of it, they were merely mocking other shows and their love triangles. Pretty much ever episode would be a favorite, but a great highlight of it would be the paintball episode, where everyone but the main character acted as if they were in a war movie.

I must say that O' Brother has to be one of the greatest movies ever made. But I agree with you that this type of comedy is rare, and it's a shame.

Think Vi has finally lost it.

Is every triangle a witches hat?

Triangle tires!

^ Quboid:
I completely agree. Come on Google! Get with the now.


^ ypsilon:
Opinion noted and there's really no way for me to refute it, as the opinion is held by many and it's pretty safe to say that it is the standard. But my opinion is that the design decisions of the past create false senses of what does and does not feel "right", and that it is not apparent until many years later when a group of people break that standard and do something different in mass, intentionally or unintentionally. In time, as people accept the change and the old guard dies off (or is assimilated), it becomes a standard in its own right.

Consider what was acceptable fashion 100 years ago versus today; what was acceptable in art, architecture, music, and culinary arts in the Western hemisphere. Think of how web design standards and video games have changed. Or our sexual zeitgeist, for that matter.

I dunno, I'd be down for a triangle view or a circular view if there were technology readily available for the masses to create with.

I'm not quite sure if smartphone designers have planned this vertical format. Take a video camera for example. You wouldn't hold it vertical to shoot a video, would you? I think you would prefer the horizontal format.

The reaseon why some people shoot videos vertical with their phones is because the common smartphone is designed to be used and held vertically. The landscape view is "just" an addon.

In my opinion there is and always will be a difference in taking a picture or shooting a video in a vertical format. A vertical video just feels wrong. Maybe youtube will fit their players to vertical formats, but I don't see that in the next three or four years.

>> ^poolcleaner:

>> ^ypsilon:
Vertical Video Syndrome!
http://www.youtube.com/watch?feature=player_embedded&v=Bt9zSfinwFA
#!
But the kid is cool

Adaptation applies to video formats, doesn't it?
The vertical format is essentially a portrait view, which although is not typical to video, is acceptable for still frames. Why? Because of accepted status quo introduced by standards required for viewing and filming because of the costs of the analog systems used to create film/video. i.e. A time when you couldn't turn your television, projection systems, or computer monitors sideways -- something that a lot more people are doing nowadays; I have a vertical monitor at work and I've seen a few massive vertical monitors used for business menus or marques. We've been due a new acceptable format for YEARS. I believe this new, viable format is the portrait view that smartphones have opened, but it's the uninitiated and unbiased that will accept this format, not us old fogies.
Now, you can go ahead and list off reasons for preferring landscape view, especially citing the typical field of view for human sight, but it doesn't invalidate the choice, considering the media was created with a camera phone, which is designed with these options in mind. Camera phone is a sub-medium, which offers it additional standards, one of which is portrait view. If the subject choice is a human, we stand vertical, so portrait really is best suited for capturing human form. (Also, caputring a BJ is best done in portrait, but that's just my perverted opinion.)
Quick, someone invent a triangle camera!

>> ^poolcleaner:

>> ^ypsilon:
Vertical Video Syndrome!
http://www.youtube.com/watch?feature=player_embedded&v=Bt9zSfinwFA
#!
But the kid is cool

Adaptation applies to video formats, doesn't it?
The vertical format is essentially a portrait view, which although is not typical to video, is acceptable for still frames. Why? Because of accepted status quo introduced by standards required for viewing and filming because of the costs of the analog systems used to create film/video. i.e. A time when you couldn't turn your television, projection systems, or computer monitors sideways -- something that a lot more people are doing nowadays; I have a vertical monitor at work and I've seen a few massive vertical monitors used for business menus or marques. We've been due a new acceptable format for YEARS. I believe this new, viable format is the portrait view that smartphones have opened, but it's the uninitiated and unbiased that will accept this format, not us old fogies.
Now, you can go ahead and list off reasons for preferring landscape view, especially citing the typical field of view for human sight, but it doesn't invalidate the choice, considering the media was created with a camera phone, which is designed with these options in mind. Camera phone is a sub-medium, which offers it additional standards, one of which is portrait view. If the subject choice is a human, we stand vertical, so portrait really is best suited for capturing human form. (Also, caputring a BJ is best done in portrait, but that's just my perverted opinion.)
Quick, someone invent a triangle camera!


IMHO it's not that it's portrait, it's that everything is geared to landscape. This video has more black space than content, why? Why isn't the YouTube embed portrait?

>> ^ypsilon:

Vertical Video Syndrome!
http://www.youtube.com/watch?feature=player_embedded&v=Bt9zSfinwFA
#!
But the kid is cool


Adaptation applies to video formats, doesn't it?

The vertical format is essentially a portrait view, which although is not typical to video, is acceptable for still frames. Why? Because of accepted status quo introduced by standards required for viewing and filming because of the costs of the analog systems used to create film/video. i.e. A time when you couldn't turn your television, projection systems, or computer monitors sideways -- something that a lot more people are doing nowadays; I have a vertical monitor at work and I've seen a few massive vertical monitors used for business menus or marques. We've been due a new acceptable format for YEARS. I believe this new, viable format is the portrait view that smartphones have opened, but it's the uninitiated and unbiased that will accept this format, not us old fogies.

Now, you can go ahead and list off reasons for preferring landscape view, especially citing the typical field of view for human sight, but it doesn't invalidate the choice, considering the media was created with a camera phone, which is designed with these options in mind. Camera phone is a sub-medium, which offers it additional standards, one of which is portrait view. If the subject choice is a human, we stand vertical, so portrait really is best suited for capturing human form. (Also, caputring a BJ is best done in portrait, but that's just my perverted opinion.)

Quick, someone invent a triangle camera!

I love World Order and I love dubstep. Together its like my eyes and ears just had sex.

I think this excerpt from Wikipedia about World Orders founder may be interesting to all of you -

Genki Sudo is a retired Japanese mixed martial artist and a kickboxer who, until December 31, 2006 competed in the Japanese fighting organization HERO'S and before that, the Ultimate Fighting Championship. He is notable for his elaborate ring entrances and unorthodox fighting style. His philosophy is "We are all one." He is a practicing Buddhist. Signature moves include the flying triangle and spinning backfist

Comment hidden because you are ignoring dag. (show it anyway)

I'm honestly not sure - might have been minor design changes on our side - but could also be browser changes, the way alt or title tags are cued. It's all going to change in VideoSift 5.0 - which I'm starting to get pretty excited about. >> ^xxovercastxx:

There used to be visual cues for a lot of these things.
The relative date and the view count used to have a dotted underline which is the standard visual cue for "more info on hover". See the right side of this page for an example. Comment timestamps could benefit from this treatment, too, as could comment voting controls.
Your username in the menubar used to have a downward pointing triangle (like the downvote button) next to it instead of your star/gem/crown to indicate that it's a drop-down menu.
@dag, any input as to why these things were removed over the years?

There used to be visual cues for a lot of these things.

The relative date and the view count used to have a dotted underline which is the standard visual cue for "more info on hover". See the right side of this page for an example. Comment timestamps could benefit from this treatment, too, as could comment voting controls.

Your username in the menubar used to have a downward pointing triangle (like the downvote button) next to it instead of your star/gem/crown to indicate that it's a drop-down menu.

@dag, any input as to why these things were removed over the years?