878: Model Rail
In model rail construction, HO scale refers to the currently most popular scale for modeling railroads, in which 3.5 millimeters in the model corresponds to 1 real-world Imperial foot. As the comic suggests, it works out to a ratio of about 1:87.1. In Europe, the scale is defined as exactly 1:87 instead, to avoid reference to US measurements.
The (apparently less-experienced) modeller wants to make an HO model layout of his town. However, the more-experienced modeller points out that this is a bad idea, due to nesting. To make it a perfectly accurate model, the modeller would have to include a model of his house, which includes his basement, which includes the model. So, he would have to make a model of the model, which will include a smaller model of the model, and so forth.
Matryoshka dolls are toys of Russian origin that can be stacked inside one another. Here, the "Matryoshka limit" is the hard barrier that follows as a result of the nesting. Matter is not infinitely divisible; once one gets the level of atoms, it's impossible to go any smaller. The unit shown in the last diagram is the ångström, a preposterously small unit of measurement that was created when humans started discovering preposterously small things, like crystal structures and wavelengths.
The rules of model train layouts reference the 1999 cult classic Fight Club, where the first rule of Fight Club is "do not talk about Fight Club." However, while the club instituted the rule because their activities were morally and legally questionable, the rule in the comic was instituted by friends and family members who, apparently, were sick of hearing the train enthusiasts talk about model train layouts all the time.
The "Philistines" comment is not referring to citizens of ancient Palestine (at least not directly), but rather the philosophy of Philistinism. Friedrich Nietzsche defined a Philistine as someone who is purely negative in how they define style, i.e. they know exactly what they hate and don't really have anything they like. A common stereotype for artists is to refer to anyone who dislikes their work as "Philistines," thus dismissing their criticism as being part of a larger personality defect on the critic's part rather than any particular failing of the artwork in question.
The title text references HO scale and, more specifically, whether it should be spelled with the letter "O" or the number zero (0). Such debates often seem petty to the "layman", yet the people involved in the debates can form very strong feelings for their side. Randall recognizes "nerdy tendencies" almost immediately when he gets the urge to take a side. The comic 1167: Star Trek into Darkness is about a similar debate on Wikipedia.
- Cueball: I want to build a perfect HO-scale (~1/87) model train layout of my town.
- Friend: In your basement? Bad idea. Never make a layout of the area you're in.
- Cueball: Why not?
- Friend: Because it'd include a little 10" replica of your house.
- Cueball: So? That's be cool! I'd make tiny replicas of my rooms, my furniture—
- Friend: —and your train layout?
- [The comic shows how the models would nest together.]
- [Layer 1: 18 meters across. The two modelers are shown standing next to it.]
- [Layer 2: 21 cm across.]
- [Layer 3: 2.4 mm across. A mosquito is shown for comparison. It stands over roughly half of the town.]
- [Layer 4: 28 μm across. A strand of spider silk is shown for comparison. It is much thicker than the roads.]
- [Layer 5: 320 nm across. A cold virus is shown for comparison. It covers roughly a quarter of the town. At this level the town becomes notably "fuzzy" as individual atoms are discernible.]
- [Layer 6: 37 Å across. The town is simply spheres (atoms) at this point. The large hill near the back is the only noticeable feature, consisting of five atoms jutting out from the mostly flat ground.]
- The Matryoshka limit: It is impossible to nest more than six HO layouts
- Cueball: My God.
- Friend: Yeah. It's the second rule of model train layouts: No nesting.
- Cueball: ...What's the first rule?
- Friend: "Do not talk about model train layouts." That rule was actually voted in by our friends and families.
- Cueball: Philistines.