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| | ==Explanation== | | ==Explanation== |
| − | This comic depicts people in different fields of study answering the question, "How many holes are there in a coffee cup?" and also compares this to what a normal person would say.
| + | {{incomplete|Created by a CAFFEINE MOLECULE WITH A HOLE DRILLED IN ITS SIDE. Do NOT delete this tag too soon.}} |
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| − | This question has different interpretations, entirely dependent upon the definition of a hole. The type of {{w|coffee cup}} shown in the comic is with a handle (like a {{w|mug}}), but [[Randall]] calls it a cup and there are also cups with handles on the Wikipedia page for coffee cups. Most people would recognize that there is a hole through the handle. | + | This comic depicts multiple people in different fields of study answering the question “How many holes are there in a coffee cup?” This question can have multiple interpretations, in particular concerning the definition of a hole. |
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| − | The comic explores the answer to the question through several peoples’ avenues of thought, and is funny because of the ambiguity:
| + | A topologist states the coffee cup belongs in the genus of one hole. A common joke is that topologists can’t tell the difference between a coffee cup and a donut since they’re homeomorphic to each other — they have the same genus. <!-- From the point of view of (reduced) [https://en.wikipedia.org/wiki/Homology_(mathematics)#Informal_examples homology] (in this case also homotopy), the coffee cup has one 1 dimensional hole and no other dimensional holes. Hence.... -- Way too jargony, topology is too obscure to reasonably ask this of readers. --> From the topologist's point of view, the coffee cup definitely has one hole. See [[2625: Field Topology]] for more information about topology. |
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| − | ===Topologist===
| + | The normal person asks for clarification about whether the opening counts as a hole. This shows flaws in the question, which suffers from the mathematically imprecise, ambiguous common usage of the word hole. |
| − | [[File:Mug and Torus morph.gif|thumb|200px|The coffee mug and donut shown in this animation both have topological genus one.]]
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| − | [[Ponytail]], a {{w|topology|topologist}}, states the coffee cup belongs in the {{w|Genus (mathematics)#Topology|genus}} of one hole. From the topologist's point of view, the coffee cup definitely has one hole, which corresponds to the opening created by the cup handle. A cup without a handle would have zero holes, as it is equivalent to a dinner plate, just an indentation in the surface. See [[2625: Field Topology]] for more information about topology.
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| − | The panel as a whole references an academic joke wherein topologists can't tell the difference between a coffee cup with a handle and a {{w|doughnut}} since they're {{w|Homeomorphism|homeomorphic}} to each other — meaning they have the same genus (i.e one hole). | + | The philosopher answers the question with an elucidating counter-question, considering a hypothetical scenario. Drilling a hole should increase the number of holes by one, and after the hole has been drilled, the coffee cup has two holes according to topologists. Since drilling a hole increases the number of holes by one, the philosopher's question requires the original questioner to reveal the answer to their own question.<!-- (This technique of seeking knowledge by asking good questions is common in Jewish tradition, e.g., Isidor Isaac Radi's mother asking him whether he "ask[ed] any good questions" at school each day.) -- likely true, but needs a citation and not in an ironic way, to avoid the appearance of endorsing a particular faith in Explainxkcd's voice. --> |
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| − | ===Normal person===
| + | The chemist looks at the cup on a molecular level, which naturally means it has lots and lots of holes: 1,000,000,000,000,000,000,000 (10<sup>21</sup> or 1 sextillion) “in the caffeine alone.” The implication is that there are more in the cup itself, depending on what material it’s made out of. Also, the coffee itself could have other holes, depending on the type of coffee. For example, espresso contains significant amounts of niacin and riboflavin, each of which has at least one hole in its chemical structure. However, this ignores the fact that bonds are not discrete sticks as portrayed in many molecular models. The "holes" in the middle of a caffeine molecule are not completely empty but instead merely have lower electron densities/probabilities. In a {{w|space-filling model}}, a caffeine molecule has zero holes. So the point-cloud duality of electron orbitals and bonds might not satisfy a topologist's, normal person's, or philosopher's criteria for a connected substrate in which holes may be formed. |
| − | [[Hairy]], representing a normal person, is not sure (the acronym "IDK" stands for "I don't know") and asks for clarification about whether the opening at the top counts as a hole. This shows flaws in the question, which suffers from the mathematically imprecise, ambiguous common usage of the word "hole." Topologists would refer to the opening as a concavity, not a hole, and while they consider such geometrical properties generally outside their field, most practical applications of topology do involve geometric components. By contrast, in everyday usage many concavities are called holes, such as a hole dug into dirt with a shovel. Hairy would say one for the handle, and two if the opening counts as a hole, which he is not certain the one asking the question thinks.
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| − | [[File:Double torus illustration.png|thumb|left|150px|A genus two surface]]
| + | In the title text, the theoretical physicist looks even deeper, at a subatomic level. Since fundamental particle interaction is governed by fundamental forces and collision instead of tensile or ductile solid connectedness, the physicists posit that any definition allowing a single hole would potentially produce a number of holes akin to the factorial of the number of particles in the universe, or at least within the cup's {{w|light cone}}, which is a number impractical to accurately count. |
| − | ===Philosopher===
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| − | [[Hairbun]], a philosopher, answers the question with an elucidating counter-question, considering a hypothetical scenario. One might expect that drilling a new hole would also increase the number of holes by one. However, as illustrated, some people would consider that the new arrangement has three holes (in addition to the handle, there is a hole at the top where coffee can be poured in, and one at the bottom where it can run out), while others would consider it to have only two (the new hole forming a continuous hole with the original opening at the top, through which coffee can run). Some might in fact say that the coffee cup now has one hole because it is leaky, disregarding the handle topology at this point. In this way she requires her interlocutor to confront the ambiguities and consider what they mean by the word 'hole' in different contexts. An interesting point about Hairbun's response is that she doesn't actually answer the question, a trope often found in philosophical replies.
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| − | [[Image:Point cloud torus.gif|thumb|200px|A point cloud of a genus one surface]]
| + | ==Transcript== |
| − | | + | {{incomplete transcript|Do NOT delete this tag too soon.}} |
| − | ===Chemist===
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| − | [[Cueball]], a chemist, looks at the coffee in the cup on a molecular level. He envisions a {{w|ball-and-stick model}} of the {{w|caffeine}} molecules in the coffee, and estimates a total number of holes of all the coffee molecules. He comes up with a truly massive number: 1,000,000,000,000,000,000,000 (10<sup>21</sup> or 1 sextillion) “in the [https://chemapps.stolaf.edu/jmol/jmol.php?model=CN1C%3DNC2%3DC1C%28%3DO%29N%28C%28%3DO%29N2C%29C caffeine] alone.” One molecule of caffeine has two rings of bonds with holes in them, multiplied by 500 quintillion molecules, or 0.00083 {{w|mole (unit)|moles}}. As the molecular mass of caffeine is about 194 grams per mole, [[Randall]] must think that the mass of caffeine in a typical cup of coffee is 161 milligrams. The coffee could have other holes, depending on the type of coffee; for example, espresso contains significant amounts of niacin and riboflavin, which have one and three rings in their chemical structure, respectively.
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| − | This estimation depends on taking the ball-and-stick model of molecules somewhat literally. However, real molecular bonds are not solid sticks, but shared electron clouds between atoms. The "holes" in the middle of a molecule's rings are not completely empty but instead merely have lower electron probability density through the middle than other parts of the bonds. So the point-cloud duality of {{w|Bonding molecular orbital|electron orbitals and bonds}} might not satisfy a topologist's, normal person's, or philosopher's criteria for a connected substrate in which holes may be formed.
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| − | [[Image:World lines and world sheet.svg|thumb|left|200px|{{w|String theory}} describes the {{w|worldline}}s of point-like particles as {{w|worldsheet}}s of "closed strings," forming topological holes; shown here as a genus two surface.]]
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| − | ===Theoretical physicist===
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| − | In the title text, a theoretical physicist looks even deeper, at the subatomic scale of {{w|Planck units}}. Since fundamental particle interaction is governed by fundamental forces and collision (per the {{w|Pauli exclusion principle}}) instead of tensile or ductile solid connectedness, the theoretical physicist posits that any definition providing for a single hole would also describe a number of holes akin to the factorial of the number of particles in the universe,[https://tel.archives-ouvertes.fr/tel-02341882/document] or at least within the cup's {{w|light cone}}, which is a number impractical to accurately count, but not uncountable in a mathematical sense.
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| − | === Practical considerations ===
| + | :[The first panel has text only. The "Q:" below is a large letter Q representing a question, not a character name.] |
| − | The main joke is that the number of holes depends on both the scale and perspective from which you are looking at the world. From a topological standpoint, when someone digs into the ground it should go all the way through (or easier, down and up again another place) before it is considered a hole, since a hole is something that some other thing should be able to pass through. But from a common usage perspective, if people dig in the ground the result is called a hole, because functionally it creates a discontinuity in to which, for example, things can be placed or fall. Similarly, the opening in a coffee cup without a handle or a bottle of beer is called a hole, even though they are topologically equivalent to a dinner plate, which normal people would never say had a hole.
| + | :Q: |
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| − | A cavity in a surface could also be considered a physical barrier, preventing movement along the surface in certain scenarios (e.g. a {{w|sinkhole}} opening up in the middle of a road) even though it may be topologically 'flat' in the most general way, and so is very open to context, and such a hole might be considered more a 'thing' than the surface that has been removed to create it. And a concavity in a vessel that can hold liquid (or a drilled hole which removes that ability) is of a different nature from the holes in the molecules that are part of the liquid therein. And such holes very different from the string-theoretical holes at the Planck scale, which don't necessarily involve barriers, containment, or any other aspects of topological connectivity. This conceptual ambiguity of what a hole is or means is demonstrated by the fictional {{w|portable hole}}, which obeys {{w|Wile E. Coyote and the Road Runner|and defies}} a normal person's preconceptions of a hole.
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| − | The topological discussion here regarding cups and doughnuts is related to the question of how many holes there are in a human, which is excellently answered in Vsauce's video
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| − | [https://www.youtube.com/watch?v=egEraZP9yXQ How Many Holes Does a Human Have?]. This also takes a good look at the topological difference between a paper cup and a mug with handle, and how one could be morphed into a plate and the other into a doughnut.
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| − | ==Transcript==
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| − | :[The first panel has text only and is phrasing a question:] | |
| − | :<big>Q:</big> | |
| | :How many holes are there in a coffee cup? | | :How many holes are there in a coffee cup? |
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| − | :[Each of the next four panels has a caption at the top to indicate the kind of person answering the question. In the first of these Ponytail stands holding a coffee cup in its handle.] | + | :[Each of the next four panels has a caption at the top to indicate the kind of person answering the question.] |
| | :Caption: Topologist | | :Caption: Topologist |
| | + | :[Ponytail stands holding a coffee mug.] |
| | :Ponytail: One. | | :Ponytail: One. |
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| − | :[In the next panel Hairy stands to the right of Ponytail, holding the coffee cup in its handle at an angle so he can to look into it.]
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| | :Caption: Normal person | | :Caption: Normal person |
| | + | :[Hairy stands to the right of Ponytail, holding a coffee mug at an angle to look into it.] |
| | :Hairy: IDK, does the opening count as a hole? | | :Hairy: IDK, does the opening count as a hole? |
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| − | :[In the next panel Hairbun is shown in closeup, holding her hand out palm up to indicate two drawings of coffee cups with handles to her left. The top drawing is larger and shows the cup with coffee inside, and a hole drilled at the bottom part of the side away from the handle. Coffee pours out of this hole. Beneath and further left is a smaller version of the same cup, but now without coffee. Instead two curved arrows goes from above to below through the hole of the handle and the hole now drilled in the bottom part of the cup. Each arrow is labeled with a question-mark.]
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| | :Caption: Philosopher | | :Caption: Philosopher |
| | + | :[Hairbun is shown in closeup, with two drawings of coffee mugs to her left.] |
| | :Hairbun: To answer that question, consider another: If we drill a hole in the side, how many holes are there now? | | :Hairbun: To answer that question, consider another: If we drill a hole in the side, how many holes are there now? |
| − | :?
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| − | :?
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| − | :[Cueball, without any cup, stands with a drawing of a caffeine molecule above and to the right of him. It has two "rings" with 5 and 6 atoms. Those rings are connected along one side. There are 9 "edges" on this, three of those has one atom attached to it and 3 others have four atoms attached to them (one atom with three others attached). The two that are at the end of the edge that belongs to both rings have no atoms attached, and the final of the 9 also has no atom.]
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| | :Caption: Chemist | | :Caption: Chemist |
| | + | :[Cueball stands with a drawing of a caffeine molecule above him and to the right.] |
| | :Cueball: 10<sup>21</sup> in the caffeine alone | | :Cueball: 10<sup>21</sup> in the caffeine alone |
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| | {{comic discussion}} | | {{comic discussion}} |
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| | [[Category:Comics featuring Ponytail]] | | [[Category:Comics featuring Ponytail]] |
| | [[Category:Comics featuring Hairy]] | | [[Category:Comics featuring Hairy]] |
| | [[Category:Comics featuring Hairbun]] | | [[Category:Comics featuring Hairbun]] |
| | [[Category:Comics featuring Cueball]] | | [[Category:Comics featuring Cueball]] |
| | + | [[Category:Math]] |
| | [[Category:Food]] | | [[Category:Food]] |
| − | [[Category:Math]] | + | [[Category:Science]] |
| | [[Category:Chemistry]] | | [[Category:Chemistry]] |
| | [[Category:Philosophy]] | | [[Category:Philosophy]] |
| − | [[Category:Physics]]
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