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Millions of people visit xkcd.com each week to read Randall Munroe’s iconic webcomic. His stick-figure drawings about science, technology, language, and love have an enormous, dedicated following, as do his deeply researched answers to his fans’ strangest questions. The queries he receives range from merely odd to downright diabolical: • What if I took a swim in a spent-nuclear-fuel pool? • Could you build a jetpack using downward-firing machine guns? • What if a Richter 15 earthquake hit New York City? • Are fire tornadoes possible? His responses are masterpieces of clarity and wit, gleefully and accurately explaining everything from the relativistic effects of a baseball pitched at near the speed of light to the many horrible ways you could die while building a periodic table out of all the actual elements. The book features new and never-before-answered questions, along with the most popular answers from the xkcd website. What If? is an informative feast for xkcd fans and anyone who loves to ponder the hypothetical.
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Randall Munroe argues that attempting to build a periodic table out of elemental bricks reveals why you cannot collect all elements: the most reactive and radioactive elements become increasingly dangerous, culminating in the synthetic heavy elements that would release nuclear-scale energy and render the scenario impossible.
- Elements progress from inert/safe (rows 1-2) to flammable (row 3) to toxic-gaseous (row 4) to mildly radioactive (row 5) to catastrophically radioactive (row 6)
- Synthetic elements at the bottom of the periodic table have half-lives measured in seconds or milliseconds, releasing all their energy instantaneously rather than over time
- The combined reaction would exceed nuclear weapon-scale energy release and render cleanup impossible due to every possible chemical reaction occurring simultaneously
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From the high-speed camera footage of Operation Plumbbob, physicists calculated a lower bound on the plug's velocity at a double-digit number of kilometers per second, with one estimate being approximately 65 kilometers per second, which approaches or exceeds the speed of the Helios 2 space probe (60-70 km/s), often cited as the fastest human-made object.
“The lower bound is a-- I tried to run through the calculations myself using the field of view of the camera. It's a little bit tricky calculate-- but it is a double digit number of kilometers per second. One of them-- one [INAUDIBLE] was about 65 kilometers per second. And that's interesting because you'll see sometimes the Helios 2 probes that we sent around the sun are often listed as the fastest human objects-- the fastest thing we've ever made. And frame of reference questions, it's hard to figure out how to define that. But with reference to the sun, the thing it was going around, they dropped so close, they whipped around it really fast, and at the bottom of that they got up to about around 60 or 70 kilometers per second.”
Americium can be extracted from smoke detectors in small quantities, allowing collectors to gather multiple smoke detectors and combine the americium to create a brick-sized sample, though this practice puts one on government watch lists.
“if you need a radioactive source for a cloud chamber, which is a science project you can do, you can take apart a smoke detector, because they'll have a tiny lump of americium in the middle of it. And if you-- it's a very small amount-- but if you wanted to make a brick, you could just buy a whole bunch of smoke detectors and disassemble them all and gather all the americium together. And this is an effective way to A, get a brick-sized sample of a rare element that's otherwise hard to find, and B, get yourself onto a bunch of government watch lists really quickly.”
Half-life selection for nuclear power involves a balance: longer half-lives mean the element is less radioactive (decays more slowly), producing less power and heat, while shorter half-lives produce more immediate energy but decay rapidly.
“the half-life of plutonium is just about right, because if it were much longer, that also means that it is less radioactive, because it's taking longer for half of it to decay, which means it will be producing less power and less heat. And so you always try to find a balance.”
Operation Plumbbob was a series of Cold War-era underground nuclear weapons tests where an underground chamber was connected to the surface via a shaft with a cement plug and iron cap, and physicists calculated that the explosion pressures would push the plug upward rather than disintegrate it.
“Back in the early days when we were still doing nuclear weapons tests, there was this series of tests underground. One of them was Operation Plumbbob, where they had a nuclear weapon going off in an underground chamber with a shaft connecting to the surface. And the shaft had a cement plug and an iron-- some kind of heavy steel-- cap on it blocking the top of it.”
Astatine, in its most stable form, has a half-life of 8 hours, meaning all the energy emitted by a plutonium space probe over a century would be emitted by an equivalent lump of astatine in an afternoon.
“astatine, in its most stable form, has a half-life of eight hours, which means that all of the energy emitted by the plutonium powering the Curiosity Rover over the course of the next century, if it keeps running, is being limited by our lump of astatine in an afternoon.”
A fluorine compound exists such that almost any substance will spontaneously catch fire when placed in a fluorine atmosphere, including ice cubes in certain fluorine compounds.
“there's a fluorine compound which, if you have a gas of this compound, and you place things in it, almost any substance will spontaneously catch fire in a fluorine atmosphere, including, for one of these compounds, ice cubes.”
Row 6 contains astatine, which is so radioactive that it decays so violently that in the moment the periodic table snapshot is taken, the table would be destroyed, and the observer would be seeing only a single moment in time before vaporization occurs.
“the only chance we will have to see this table is the snapshot taken right at this moment, because-- so plutonium is radioactive. And we use it-- we use uranium in reactors, where we trigger chain reactions in the uranium.”
Row 7 elements create decay chains where element 118 decays and releases protons/neutrons, becoming element 116, which is also extremely radioactive and short-lived, continuing this cascade of decay chains that release energy cumulatively rather than in a single chain reaction.
“However, there is sort of a chain element, because the elements that are up way far on the periodic table, some of them will emit a couple of protons and neutrons, which now makes-- element 118 has 118 protons-- it decays immediately, releases some protons, and becomes element-- maybe it drops down two spaces-- it becomes element 116, which is also extremely radioactive and has a very short half-life. And so you get these decay chains, all of them pouring out a whole bunch more and more and more energy all at once.”
Derek Lowe asked whether the carbon in the periodic table could be specified as diamond, and noted that diamond can burn if you get it hot enough, but the question is whether an explosion violent enough to incinerate diamond would fling it away before delivering enough energy to destroy it.
“his first question was, if you're going to build this, this would definitely not be a good idea. He said, so what form is the carbon in? Do I get to specify? Do I get to be a giant chunk of diamond? And I said, I don't know. And he said, well, because diamond, it will actually burn if you get it hot enough. But that's pretty difficult. And you'd have sort of the problem-- the same thing that happened with some of the Cold War-era projects, which is if you have an explosion like this, that's this violent, the question is will it fling the thing away before it delivers enough energy to disintegrate it?”
No one has ever collected enough astatine to see it with the naked eye because any sample large enough to see would melt the eye and vaporize itself from its own radioactive heat.
“This is why no one has ever collected enough of a sample of astatine to really look at it, because any sample large enough to see with a naked eye would also melt the naked eye and vaporize itself from its own heat.”
Fluorine is the most reactive element in the periodic table, and there is a documented history of chemists being mauled or killed during fluorine experiments.
“Fluorine is really, I think, the worst element. It's the most reactive element in the periodic table, and I was recently reading a list of chemists who have been mauled or killed doing fluorine experiments.”
Fluorine will eat through many common gas mask materials, so standard safety equipment is inadequate for handling fluorine.
“I do remember seeing in a data sheet that it will also eat through many common gas mask materials. So be careful with your safety equipment.”
Arsenic is widely present in trace amounts (parts per million or billion) in all food, and these trace amounts are not toxic, but a solid lump of arsenic represents a dose large enough to be toxic to virtually all forms of life.
“there are trace amounts of arsenic in just about everything. So all of our food has a little bit of arsenic in it-- few parts per million or billion-- and that's OK. And there could be a little bit more than that, and it's also OK. It's not going to be toxic. But on the other hand, this is a lump of arsenic, one part per lump. And the reason that we-- even though there is a little bit of arsenic in everything-- the reason we have these associations for it is that in large enough quantities it is toxic to virtually all forms of life.”
Plutonium undergoes radioactive decay and emits heat; this heat is used to power long-term space probes like the Curiosity Rover, which has a chunk of plutonium on an extended arm held away from the rover.
“if you have plutonium sitting there, it's radioactively decaying, and so it emits heat. And that is what we used to power a bunch of the long-term space probes. So the Curiosity Rover has-- and I really find this amusing for some reason-- but they have a chunk of plutonium, which-- I think we've come very close to running out at this point and may be buying it from Russia.”
Row 7 contains elements that are synthesized in particle accelerators, have not been assigned names (only systematic numerical names like 'unun-something-ium'), and element 118 was only recently synthesized, completing the periodic table for the first time in history.
“we're getting down into the elements that just have numbers, and they have not settled on names yet. When I was a kid and learning the periodic table-- and playing Pokemon and being really totally well-adjusted and very, very popular and social, but also memorizing the periodic table-- I found there were a whole bunch of elements that got you up to 100-- you could get up to 105 or so, or 110. Some of the books I had went up to 110. But then they stopped, and all of those didn't have names. They would just be like 'unun-something-ium' that was like this naming convention. And they've start assigning names recently. They've started finishing it up. But we're also at a really interesting situation, which is that they have synthesized elements, as of a couple of years ago, they finally synthesized element number 118 in a particle accelerator”
Munroe consulted Derek Lowe, a chemist who writes the drug industry blog 'In the Pipeline,' to verify the chemical reactions described in the periodic table article, and Lowe confirmed that the reactions would happen but also identified additional dangerous reactions Munroe had not considered.
“I talked to Derek Lowe, who's a chemist who also writes the drug industry blog 'In the Pipeline,' which I had read for a while. And so he went through my article. And actually his first question was, if you're going to build this, this would definitely not be a good idea.”
Derek Lowe confirmed that selenium and bromine would react vigorously, that fluorine is the point where the scenario 'goes to hell,' and that fluorine would have an 'armed truce' with chlorine but severe reactions with everything else.
“he pointed out that the selenium and the bromine would react vigorously. He said the fluorine-- he said you're right that fluorine is where this whole scheme goes to hell. That the fluorine, he said, it would be OK with the neon, and it would observe sort of an 'armed truce' with the chlorine, but everything else-- his exact words were 'but everything else, sheesh.'”
Munroe's favorite 'What If' questions come from young children, who ask straightforward questions (like 'Can I build a billion-story building?') that lead to unexpected analytical directions, whereas adult submissions tend to be more contrived and designed to produce dramatic/catastrophic scenarios.
“I actually find some of my favorite questions come from little kids, because adults will sort of try to be really clever about it and come up with a question that suggests all these horrible consequences, and they've set up a scenario that's going to result in a mushroom cloud engulfing wherever it is you're doing this. Whereas little kids will ask extremely straightforward questions like, I want to build a billion-story building. Can I do that? And then answering takes you in a bunch of unexpected directions.”
Munroe's articles frequently end with catastrophic or apocalyptic scenarios, not because he is being dramatic, but because those are the actual consequences of the hypothetical scenarios people submit, and he consults experts to verify that he is not overselling the science.
“people say that I write all these articles, and how come I destroy the earth so often? And how come the articles always end with everyone dying or something? And it's really because that's the questions that people ask me. That would really be the consequence of the scenario you're talking about. But I'm trying to not make them more dramatic than they are. I'm trying to tell the real story of what would happen in as fun a way as possible. But especially with the chemistry things like this, I liked going to experts to find out-- make sure I'm not overselling this.”
Munroe received concerning 'What If' submissions including one from someone with apparent nuclear weapons access asking about nuclear physics, and another from a medical doctor asking about the effects of a toxin on patient receptors at a specific dose, suggesting potential misuse scenarios.
“I had one person who in their job may have conceivably-- they asked a question about-- a fun earth science question involving nuclear weapons. And their from address, the TLD that it was coming from, and the title that was after their signature, and then some of what they described in the letter suggested that perhaps this was a person who had access to nuclear weapons. And that was a little worrying. I have also gotten ones from-- I had one that I think came from a doctor that was like, suppose that a toxin blocks the effect of so and so on a patient's so and so receptors, and it was delivered at this dose, what would be the effect of this toxin?”
The comprehensive understanding of element collection hazards has resolved Munroe's Pokemon-inspired frustration about only being able to collect 85-90 of 118 elements, because the most important lesson is that you must not catch them all.
“this, if nothing else, definitely helped me come to terms with my sort of Pokemon-inspired frustration that you can only buy 85 or 90 of the 118 elements, because this has really driven home that the most important thing an element collecting is that you do not catch them all.”
Munroe uses unfocused Wikipedia and paper reading during late-night unproductive hours, which often provides answers to questions that arrive weeks later.
“just there hits a point in the night where I stop getting anything productive done. And if I have Wikipedia tabs open, I'll just start reading from there, and it will never be anything useful for what I'm doing right then, but often I'll learn all about something that two weeks later is the answer to a question that comes up. So just a lot of totally unfocused reading of Wikipedia or weird papers ends up coming in handy later on.”
Further calculations suggest the Operation Plumbbob plug likely did not survive atmospheric re-entry impact due to insufficient size, resulting in a meteor burning upward through the atmosphere in a plasma trail, possibly the only time in Earth's history a meteor traveled directly upward.
“But it's also sort of a moot point, because further calculations show that probably the metal cover, because it was not quite large enough, probably did not survive the impact with the atmosphere. So it would have been sort of the only-- maybe the only time in Earth's history that we've seen a meteor going directly upward, burning up in a plasma trail.”
Adding Earth's 30 kilometers per second orbital speed around the sun to the manhole cover's velocity could potentially push its speed over 100 kilometers per second if aimed in the right direction.
“you get to add on the Earth's 30 kilometers a second speed around the sun, when you're trying to get up to the escape velocity. And so this thing could be going over 100 kilometers a second, which would send it straight out of the solar system.”
Consulting expert chemists revealed that reality is far more horrifying and strange than Munroe's initial analysis, and this discovery process of finding that reality exceeds imagination is the most rewarding aspect of the research and writing process.
“And it's really nice to learn that, in fact, reality is way more horrifying than I was able to imagine. And I think that's been the most fun thing about doing all of this, is getting to discover all this really crazy and exciting and fun and uplifting and sometimes really terrifying stuff that the science can show us.”
Building the periodic table experiment with astatine represents a 'quantity that maximizes the amount of paperwork you're going to have to face' because a smaller amount might be coverable (charred walls, radioactivity, discretely cleanable with 20% time), but a liter would demolish the building, while a larger amount would leave no one to submit paperwork.
“the amount of astatine that you would be using here is a quantity that maximizes the amount of paperwork you're going to have to face, because if it were smaller-- a liter is enough that it will probably demolish the building that you're doing this in. And there are going to be a lot of people asking questions.”
Munroe receives a large volume of 'What If' question submissions and has implemented email filters to automatically delete or sort questions containing certain keywords, including the names of invulnerable superheroes and the word 'woodchuck' (after receiving 70-80 identical woodchuck jokes in the first week).
“there are definitely a lot of questions submitted, and I will admit to doing-- there's some sort of filters that I put on the inbox. So after a little bit I started filtering out the names of all of the invulnerable superheroes, because they were just too many questions about them that were never ones that I was going to be able to answer. I also filtered out the word 'woodchuck' after week one. Because the first time someone submitted 'hey, how much would could a woodchuck really chuck if a woodchuck could chuck wood?' I laughed. I was like that's funny, and then the second time I was like, oh, yeah, hey, someone else thought of that joke. And then in the first week it was like 70 or 80 emails that were just the same woodchuck joke”
The seven rows of the periodic table pose escalating dangers: rows 1-2 are buildable without trouble; row 3 will burn you with fire; row 4 will choke you with toxic smoke; row 5 will replicate rows 1-3 dangers plus give mild radiation; row 6 will disintegrate instantly in superheated steam and extremely toxic dust; row 7 should not be built.
“Because we have seven rows to build-- so of these rows, the first two rows really you can build without too much trouble. The third row will burn you with fire. The fourth row will choke you with toxic smoke. The fifth row will do all of the things that the first rows did, plus give you a mild dose of radiation. The sixth row will disintegrate instantly in a column of steam and extremely toxic dust and smoke and destroy whatever building you're doing this in. And you should not build the seventh row.”
Munroe has learned to quickly skim research papers and PDFs to identify relevant material, and to rapidly discard irrelevant results, enabling him to research complex topics efficiently despite not being a domain expert.
“I think one sort of skill that I have gained that I didn't really have before this, was I have learned to read-- skim-- a whole lot of research that does not turn out to be relevant really fast. Like download 40 PDFs on some subject, skim each one looking for, does this have the equation that I'm looking for? Does this have something that I'm looking for-- and discard them really quickly”
Element collectors typically top out around 80 to 90 elements, depending on comfort with health and safety risks, available funding, and willingness to violate international laws (particularly regarding plutonium).
“people who try to collect them usually top out somewhere around 80 to 90, depending on how comfortable you are with your health and safety, how much money you have to put into this, and-- in the case of plutonium-- how many international laws you're willing to violate.”
Munroe refuses to answer reasonable questions that are nonetheless emotionally unbearable, such as whether teeth could be chilled to a temperature where drinking hot coffee would cause them to shatter, because he cannot research the topic without sustained discomfort.
“there are a bunch where they're totally reasonable, legitimate, answerable questions that I still just refuse to tackle. Which are like-- one of them was someone asked would it be possible to chill your teeth to such a low temperature that drinking a cup of hot coffee would cause them to shatter? And I included this question, and I have never been able to get beyond the end of that sentence without just cringing, because I imagine it. And so I have never-- I don't have the stomach to do the research to answer that question.”
Derek Lowe noted that burning selenium produces a smell worse than sulfur, describing it as making sulfur smell like Chanel No. 5 perfume by comparison, and that burning selenium and tellurium would be extremely unpleasant.
“he said that this would be really toxic, but also the selenium would be burning, and burning selenium is the worst thing that he'd ever smelled. And he said it's like-- he said it makes sulfur smell like Chanel. So the selenium and the tellurium and would both be really, really awful smelling.”
In addition to all radioactivity and chemical hazards, there is a liter of fluorine in the row 7 mushroom cloud, which would be a major concern when considering survival strategies.
“at this point, it's definitely the least your problems, but all I can think is also there's a liter of fluorine in there too. And I'll just have my gas mask, and I'd be thinking about that too.”
When searching for obscure research (particularly declassified Cold War documents or non-mainstream papers), appending 'PDF' to Google search terms yields higher hit rates than specialized academic databases like ResearchGate, JSTOR, or arXiv.
“I have found that if you're looking for weird research that maybe isn't the easiest to find-- maybe it was a government study in the Cold War that has been declassified, but not really they haven't published. I have a lot more luck just googling for the search terms that I would been looking for and adding 'PDF' to the end. In terms of does this get me a paper that answers the question I'm looking for, that has a higher hit rate than any of the specialized services.”
In one D&D session, Munroe immediately identified a logical exploit: using a magically-enchanted weapon (heavy to others, light to him) on a water wheel, so that as it rotates and the weight alternates between heavy and light, it spins faster and faster, eventually creating a weapon of tremendous kinetic energy.
“The one time I did play Dungeons and Dragons, the DM was like, OK, your character. You've at this point picked up a weapon, which only you can pick it up. It's magically enchanted. If anyone else-- it's a 10-pound ax-- or something, and if anyone else picks it up, it weighs 1,000 pounds. If anyone else touches it, in fact, it weighs 1,000 pounds. And I was immediately like, OK, wait a minute. Is there a water wheel in this town? Can I get someone else from the party or a peasant or someone? I want to strap the ax to the water wheel, and have the handle sticking out, like my hand on one side and their hand on the other side.”
Munroe has learned more about geology (continental breakup), biology, and chemistry through research for answering questions, and has found that he has historically had more difficulty with chemistry because abstract concepts like electronegativity don't connect intuitively to real-world experience compared to physics concepts like mass, speed, and force.
“I got this-- I had come up with the scenario. And I have physics background. And in doing what-- I've gotten a lot more into geology. I was learning about the way continents break apart as you do various horrible things to them-- that's been a lot of fun. And I've also learned a lot more biology lately, but I feel like chemistry has always been something that I've had a harder time with, maybe just because there are a lot of things that-- this atom is more electronegative than this atom. But we don't have a real life-- it's sort of harder to connect that to real life.”
Mercury, depending on its form, can cause mercury poisoning which is very harmful, and beryllium, while not radioactive, is dangerous to handle and should not be touched with bare hands or allowed to contact food.
“a lot of these elements, in addition to being maybe hard to find and/or some degree of illegal, some of them are kind of dangerous to handle. So mercury, depending on what form it's in, can cause mercury poisoning, which is really bad. Even some of the elements up near the top of the table, like beryllium, is-- it's not radioactive or anything-- but you don't want to get it on your hands and into your food.”
Radioactive fallout gets its name because heavy dust and uranium-contaminated particles fall out of the mushroom cloud as it cools, which is why it is literally called 'fallout'—material falls out of the cloud.
“when you have a mushroom cloud, and you have all the heavy dust and stuff with the uranium dust on it that is in the mushroom cloud, but it's heavier than air-- so as it cools, it falls down from the cloud on to the ground, which is actually why it is called fallout, because it falls out of the mushroom cloud. And I guess that's sort of obvious in retrospect, but it had never occurred to me until just now.”
The first row of the periodic table contains only hydrogen and helium, both of which can be obtained relatively easily (helium is sold at party stores), but would be anticlimactic as bricks because they would diffuse and float away.
“the first row of the periodic table is just hydrogen and helium. And that would be easy to build, because you get a bunch of hydrogen, get a bunch of helium. I think we have a helium shortage, but you can still buy it at party stores. And so you if you made a brick of those, it would be really anti-climactic. It would just sort of diffuse and float away”
Of the 118 elements in the periodic table, approximately 30 can be obtained at a local supermarket, including aluminum, oxygen, and nitrogen.
“of the 118 elements in the periodic table, there is about 30 of them which you can get at the local supermarket. You can get samples of aluminum. You can get samples of-- oxygen and nitrogen are not hard to find, either.”
The correct response to row 4 hazards is to run away very quickly and stop building rows, rather than proceeding to rows 5-7.
“So the right thing to do here is to run away very quickly and not keep building rows, which is what we're going to do.”
The completion of the periodic table (filling row 7 with element 118) is aesthetically satisfying because it creates a square, rounded-off shape in the table, which Munroe finds so satisfying that he wishes to sabotage particle physics experiments to prevent synthesis of element 119 and preserve this perfect rectangular form.
“all the periodic tables I learned as a little kid had an extra line that ended halfway across. And I don't know if it's a typographic thing, but I feel like it's very, very satisfying have the nice, square, rounded-off shape. And it gives me this weird urge to sabotage particle physics experiments, so they don't synthesize element 119 and ruin the really nice justification.”
To cradle technetium against your body for a day, eat a chunk of it, or wear it as a hat could give you a lethal dose of radiation.
“The "tech-net-ium" or technetium is not radioactive enough to kill you. At least, I think you would have to cradle it to your body for a day or so, or if you managed to eat a chunk of it, or wore it as a hat that could give you a lethal dose.”
Munroe appreciates Google Voice transcription improvements, particularly the shift from needing to mode-switch five times to enable voice commands, to eventually being able to discretely ask voice queries like 'what's the weather' without explicit mode activation.
“I've been really enjoying the rate at which the voice recognition has been improving. Especially recently, to where we're finally getting to the point where do not have to mode switch five times to get voice commands up, to then say, OK, now I want to search for this in a clear, loud voice projecting to everyone. I'm really looking forward to the future where you can just kind of discretely be like, oh, what's the weather right now? OK, it's this.”
During research for a 'What If' article about the most expensive thing to put in a shoe box, Munroe searched for prices of hard drugs and noticed his search history showed queries like 'How much does heroin cost?' which he now treats as potentially placing him on watch lists.
“there was a question I answered where I was writing about the most expensive thing you could put in a shoe box. And I've looked up prices of a bunch of hard drugs and then realized my search history is now how much does heroin cost? How much does LSD cost?”
Munroe spam-accessed the Library of Congress API while trying to randomly sample their collection, which resulted in the API blocking him and his entire building being redirected to a 403 error page.
“And then I parallelized that, because that was going too slowly. And then I found it was really hard to get good data. And so I was ramping up the number of requests I was making. And then suddenly they stopped returning anything, and then I found that not only had the API blocked me, but the entire Library of Congress website was now redirecting me to a 403.”
Munroe did not grow up playing Dungeons and Dragons socially, and instead played single-player NetHack and Angband for several years, giving him secondhand knowledge of D&D mechanics rather than direct experience.
“Coming back to this theme again, the more social geeky pursuits, I didn't really get into until I went away to college. And then eventually got a job working with more geeky people. So when I was a kid, I knew about Dungeons and Dragons but never actually played it with people. So what I did is I got a bunch of-- my closest exposure to it was the single player NetHack and derivatives, Angband and stuff, which I played through for several years every day.”
Munroe receives many transparent homework-assignment questions (e.g., 'If a ball is on an inclined plane at X degrees and Y centimeters long, how many seconds to hit the bottom?') which he refuses to answer on principle.
“I also get a lot of questions that are very transparent attempts to get me to do people's homework. Like, what if you had a ball was on an inclined plane at this many degrees that was this many centimeters long, and you let it go? Like, how many seconds do you think it would take to hit the bottom? Like, nice try.”
Comic 446 on xkcd (mentioned during Q&A) included references to Google Voice, and these references were positive/funny rather than critical.
“Sometimes I'll have people come up and say, oh, I really liked in comic 446. Can you say, is that from experience? And then they pause for a minute. And I have a moment where I'm like, oh god, they think that I know them all by heart.”