Reading the Comics, August 10, 2019: In Security Edition


There were several more comic strips last week worth my attention. One of them, though, offered a lot for me to write about, packed into one panel featuring what comic strip fans call the Wall O’ Text.

Bea R’s In Security for the 9th is part of a storyline about defeating an evil “home assistant”. The choice of weapon is Michaela’s barrage of questions, too fast and too varied to answer. There are some mathematical questions tossed in the mix. The obvious one is “zero divided by two equals zero, but why’z two divided by zero called crazy town?” Like with most “why” mathematics questions there are a range of answers.

Evil Alexa: 'I ordered a spanking for you: express.' Sedine: 'DIE!' Michaela: 'How 'we defeat this evil genius? (To the home-assistant) What's the diffrence between wrong and right? Who's got better fries, McD or BK? Why's a ball round? Is a wingless fly a 'walk'? Why'z all this communism so capitalistic? If Jeff Bezos is so rich why'zint he abel to own a toupee? Zero divded by two equals zero, but why'z two divided by zero called crazy town? So if infinity is forever, isn't that crazy too? If reality is a human construck why does my mommy act so normal? Tell me!' Sputtering Alexia: 'I - I must compute!'
Bea R’s In Security for the 9th of August, 2019. This is a new comic strip for these parts. So this essay and any future ones which explore topics raised by In Security are to be be at this link.

The obvious one, I suppose, is to appeal to intuition. Think of dividing one number by another by representing the numbers with things. Start with a pile of the first number of things. Try putting them into the second number of bins. How many times can you do this? And then you can pretty well see that you can fill two bins with zero things zero times. But you can fill zero bins with two things — well, what is filling zero bins supposed to mean? And that warns us that dividing by zero is at least suspicious.

That’s probably enough to convince a three-year-old, and probably most sensible people. If we start getting open-mined about what it means to fill no containers, we might say, well, why not have two things fill the zero containers zero times over, or once over, or whatever convenient answer would work? And here we can appeal to mathematical logic. Start with some ideas that seem straightforward. Like, that division is the inverse of multiplication. That addition and multiplication work like you’d guess from the way integers work. That distribution works. Then you can quickly enough show that if you allow division by zero, this implies that every number equals every other number. Since it would be inconvenient for, say, “six” to also equal “minus 113,847,506 and three-quarters” we say division by zero is the problem.

This is compelling until you ask what’s so great about addition and multiplication as we know them. And here’s a potentially fruitful line of attack. Coming up with alternate ideas for what it means to add or to multiply are fine. We can do this easily with modular arithmetic, that thing where we say, like, 5 + 1 equals 0 all over again, and 5 + 2 is 1 and 5 + 3 is 2. This can create a ring, and it can offer us wild ideas like “3 times 2 equals 0”. This doesn’t get us to where dividing by zero means anything. But it hints that maybe there’s some exotic frontier of mathematics in which dividing by zero is good, or useful. I don’t know of one. But I know very little about topics like non-standard analysis (where mathematicians hypothesize non-negative numbers that are not zero, but are also smaller than any positive number) or structures like surreal numbers. There may be something lurking behind a Quanta Magazine essay I haven’t read even though they tweet about it four times a week. (My twitter account is, for some reason, not loading this week.)

Michaela’s questions include a couple other mathematically-connected topics. “If infinity is forever, isn’t that crazy, too?” Crazy is a loaded word and probably best avoided. But there are infinity large sets of things. There are processes that take infinitely many steps to complete. Please be kind to me in my declaration “are”. I spent five hundred words on “two divided by zero”. I can’t get into that it means for a mathematical thing to “exist”. I don’t know. In any event. Infinities are hard and we rely on them. They defy our intuition. Mathematicians over the 19th and 20th centuries worked out fairly good tools for handling these. They rely on several strategies. Most of these amount to: we can prove that the difference between “infinitely many steps” and “very many steps” can be made smaller than any error tolerance we like. And we can say what “very many steps” implies for a thing. Therefore we can say that “infinitely many steps” gives us some specific result. A similar process holds for “infinitely many things” instead of “infinitely many steps”. This does not involve actually dealing with infinity, not directly. It involves dealing with large numbers, which work like small numbers but longer. This has worked quite well. There’s surely some field of mathematics about to break down that happy condition.

And there’s one more mathematical bit. Why is a ball round? This comes around to definitions. Suppose a ball is all the points within a particular radius of a center. What shape that is depends on what you mean by “distance”. The common definition of distance, the “Euclidean norm”, we get from our physical intuition. It implies this shape should be round. But there are other measures of distance, useful for other roles. They can imply “balls” that we’d say were octahedrons, or cubes, or rounded versions of these shapes. We can pick our distance to fit what we want to do, and shapes follow.

I suspect but do not know that it works the other way, that if we want a “ball” to be round, it implies we’re using a distance that’s the Euclidean measure. I defer to people better at normed spaces than I am.

Wavehead, standing in front of a digital blackboard which has the problem 3 + 5 on it: 'I'm just saying, with all the computing power in this electronic board, I bet it could take care of this itself.'
Mark Anderson’s Andertoons for the 10th of August, 2019. The handful of times that I’ve mentioned explore Andertoons around here can be found at this link.

Mark Anderson’s Andertoons for the 10th is the Mark Anderson’s Andertoons for the week. It’s also a refreshing break from talking so much about In Security. Wavehead is doing the traditional kid-protesting-the-chalkboard-problem. This time with an electronic chalkboard, an innovation that I’ve heard about but never used myself.

Molly: 'We'll play after I finish my homework. I'm studying pi.' Bear: (Panel filled with the word GUSH! His mouth dangles open, and he drools.) 'You said pie!!'
Bob Scott’s Bear With Me for the 10th of August, 2019. Appearances by Bear With Me should be at this link. This strip originally ran the 15th of October, 2015, when the comic was titled Molly and the Bear.

Bob Scott’s Bear With Me for the 10th is the Pi Day joke for the week.


And that last one seemed substantial enough to highlight. There were even slighter strips. Among them: Mark Anderson’s Andertoons for the 4th features latitude and longitude, the parts of spherical geometry most of us understand. At least feel we understand. Jim Toomey’s Sherman’s Lagoon for the 8th mentions mathematics as the homework parents most dread helping with. Larry Wright’s Motley rerun for the 10th does a joke about a kid being bad at geography and at mathematics.


And that’s this past week’s mathematics comics. Reading the Comics essays should all be gathered at this link. Thanks for reading this far.

Advertisements

Reading the Comics, August 9, 2019: Venn Diagrams Edition


Thanks for sticking around as I finally got to the past week’s comic strips. There were just enough for me to divide them into two chunks and not feel like I’m cheating anyone of my sparkling prose.

Sandra Bell-Lundy’s Between Friends for the 4th is another entry in this strip’s string of not-quite-Venn-Diagram jokes. As will happen, the point of the diagram seems clear enough even if it doesn’t quite parse. And it isn’t a proper Venn diagram, of course; a Venn diagram for five propositions has to have 31 regions, representing all the possible ways five things can combine or be excluded. They can be beautiful to look at, but start losing their value as ways to organize thought. This is again a Euclid diagram, which doesn’t need to show every possible overlap.

Five pairwise intersecting circles labelled 'Job Requirements', 'Parent Assistance', 'Supportive Mother', 'Husband Attention', and 'Household Upkeep'. Susan is flopped in her chair, thinking, 'Finally! NOW I can put myself first.'
Sandra Bell-Lundy’s Between Friends for the 4th of August, 2019. Essays in which I discuss something brought up by Between Friends should be at this link.

Michael Jantze’s The Norm 4.0 for the 5th is the other Venn Diagram joke for the week. Again properly the first one, showing the complete lack of overlap between two positions, is an Euler rather than a Venn diagram. The second, the “Amity Venn diagram on planet X”, is a Venn diagram and showing the intersection of blue and yellow regions as green is a nice way to show that. (I’m not fond of the gender stereotyping here, nor of the conflation of gender and chromosomes. But the comic strip does have to rely on shorthands or there’s just not going to be the space to compose a joke.)

Label: Venn Diagrams of Amity. The Amity Diagram of Planet Y. Two separate bubbles, Bro 1 and Bro 2, each arguing the designated hitter rule; Norm points out, no overlap. The Amity Diagram of Planet X. Two bubbles nearly completely overlapped, their colors blending together; one says 'This is a wonderful pinot grigio' and the other 'This is an amazing pinot grigio', and Norm thinks he needs a bigger marker to color this in.
Michael Jantze’s The Norm 4.0 for the 5th of August, 2019. Essays mentioning The Norm, either the current (“4.0”) run or older strips being rerun, should be at this link. There aren’t many, which is a shame. I like the comic.

Harry Bliss’s Bliss for the 6th name-checks tetrahedrons. These are the shapes the rest of us would probably call pyramids or perhaps d4. It’s a bit silly to suppose a hairball should be a tetrahedron. But natural processes will form particular shapes. The obvious example is the hexagonal prisms of honeycombs, which come about for reasons … I’m not sure biologists are completely agreed on. Hexagons do seem to be efficient ways to encompass a lot of volume with a minimum of material, at least. But even the classic hairball looks like that for reasons, related to how it’s created and how it’s expelled from the cat. They just don’t usually have corners.

Man, looking over a cat that's coughing up small pyramids: 'Ross, get in here! Mittens is coughing up hair-tetrahedrons again!'
Harry Bliss’s Bliss for the 6th of August, 2019. No credit to Steve Martin this time. Essays with a mention of Bliss should be gathered here.

Niklas Eriksson’s Carpe Diem for the 9th has you common blackboard full of symbols to represent mathematical work. It also evokes a well-worn joke that defines a mathematician as a mechanism for turning coffee into theorems. The explosion of creativity though is true to mathematicians, though. When inspiration is flowing the notes will get abundant and start going in many different wild directions. The symbols in the comic strip don’t mean anything. But that’s not inauthentic. The notes written during an inspired burst will be nonsensical. The great idea needs to be preserved. It can be cleaned up and, one hopes, made presentable later.

Man pointing to a line of equations on the blackboard, and where it goes from a single line to several lines of weaving expressions, with many arrows from one to another, and a lot of exclamation points: 'And here's the historic moment with Smith brought me a large cup of coffee.'
Niklas Eriksson’s Carpe Diem for the 9th of August, 2019. The essays discussing something raised by Carpe Diem should be at this link.

This and other Reading the Comics posts are at this link. I should have a fresh one on Thursday, wrapping up the past week.

I Got Arithmetic Wrong, And Learned Something About Writing


I’ll get to the comics soon enough. Interesting me right now is that I made a mistake in my review of the July reading statistics around here. Naturally I want to fix my mistake. But I also thought some about why I thought this an interesting mistake to make. This got me to think a bit about story.

I had made a spreadsheet to work out twelve-month running averages. This for things like the number of page views, number of comments, and number of posts, and all that. Since it was easy to calculate, I also worked out the number of page views per posting. I’m convinced that the number of things I post is the factor I can most control in how well my stuff gets read. And then went on to the number of unique visitors per posting, comments per posting, and number of likes per posting. Fine enough, but I set up the spreadsheet wrong. Instead of dividing the number of unique visitors by the number-of-posts column, it divided by the views-per-post column. And the likes-per-post column divided the number of likes by the number of unique-visitors-per-post. And so on.

I’d like to say I noticed this failed a sanity check. 870 unique visitors for 11 posts, and I claim this to be 7.1 unique visitors per post? Not likely. And then left it in to see if anybody noticed, which of course they did not. No, I didn’t do that; I don’t do that sort of stunt except as a marked joke. Or after warning my class that the story problems might contain unreliable data and they’re expected to ask questions. I did notice the numbers made no sense while writing the statistics-review post for my humor blog, though.

So what do I find interesting about this? Not that I made the mistake. Everyone who works makes mistakes. That I did not notice the mistake is interesting. I can make excuses which of course I find reasonable and justifiable. They all amount to that I chose to do things besides think about what numbers I should expect, and that I did not edit my copy enough before publishing.

Why did nobody notice the mistake? One answer is that nobody read the post, which is plausible enough. WordPress claims the page has gotten 17 views (as of my writing this). My home page, which has the article at its top, has gotten 42 views as well. But a view and perusal are different things. Even if people read my outstanding prose for comprehension, were they reading the numbers? Close enough to notice the claimed numbers didn’t make sense?

My guess is they didn’t. I know when I read for pleasure I tend to accept numbers as things which are present but which don’t need my immediate attention. If the presented argument needs the numbers, I’ll go back and pay attention to whether they’re 7.1 or 79.1. I suspect many people are the same way.

Elmore Leonard famously offered the writing advice to leave out the parts people skip. But people seem to skip these numbers. One might say I skipped them too and I wrote them. This did not make the post unpopular, though. I don’t know why the WordPress readership blog is always a popular post, but it is.

It’s easy to suppose the post would be more popular if it had no numbers. But a readership statistics post without readership statistics? That’s obviously daft. Maybe the box charts and map of countries would be appreciated. Pictures are the other thing besides number of posts that’s within my control and that brings readers.

I think there’s something in the nature of stories going on here. A (nonfiction) narrative builds on facts. If you have none, you may have some fine writing, but you have no story. But a mere fact? We have a word for a bare fact isolated from any narrative, any story about its value: trivia. No one could ever care about the average number of unique viewers per posting around here over the past twelve months. Someone could care about whether this viewers-per-posting is rising or falling, or how fast. The exact numbers, the trivia, are nothing. And we notice this in reading, and accept that we will never care about them. It is the story which uses them that’s of interest, and that people are happy to see. It’s easy, even for a pop mathematics writer, to think that of course numbers are what matters. And they matter, but only a tiny bit. The numbers are there so that the words around them have something to be about. It’s a neat lesson to myself about what mathematics writing means to do.


The correct calculations by the way change the story a little. Not much. This seems weird at first. It supports my contention that the number of page views and unique visitors and comments and likes all scale with the number of posts made, though. A month with twice as many posts probably got about twice as many unique visitors.

I had thought the number of unique visitors per posting rose slightly. Not too much. This is right in kind, but wrong in scale. The twelve-month running average was 60.2 unique visitors per posting and in July there were 79.1. That’s above average enough to matter. I had thought the number of likes per posting went from a twelve-month average of 8.8 down to 6.4. In fact the average was 4.4 and it drifted down to 4.1, still a decline but less sharp of one. One that might not be significant at all. The number of comments per posting I thought had dropped from 3.6 on average to 3.3. In fact the average number of comments per posting had been 1.5, and in July it rose to 1.9. This is the only change in direction of any of these trends. But my suspicion is this is so slight a change that it’s indistinguishable from random fluctuations. Noise, as they say.

How July 2019 Treated My Mathematics Blog


If I had regular readers, one might notice it’s pretty late in the month without my having reviewed readership around here for the past month. This is so. There’s good reason: the first week of August was mostly wiped out by my attending Pinburgh, the world’s largest pinball tournament, and related activities. This included four(!) amusement park visits in Pennsylvania. Pennsylvania, for some reason, has many amusement parks and they’re all worth a visit.

That’s all time-consuming stuff, though. And it’s not stuff that I can write ahead of time. This offends me, since so much of the structure of these reviews is imposed by the list of what data I have available. I suppose I could do a fill-in-the-blanks template but … why?

Well, here’s the most basic stuff: how many things got views, and how many people came around, in July 2019?

Bar chart showing monthly readership for the last three and a half years. After several months of decline the views has leapt up again.
I know it’s dangerous for me to start making spreadsheets, but I’m confident it will be all right. There are times I’ve gotten over some statistic or other. For example, do you ever see me going on about views per visitor these days? I mean apart from this, right here. I’m sure I have better things to worry about, probably.

That’s … surprising. I had 11 posts in July, most of them Reading the Comics pieces. But this brought 1,356 page views, above a thousand for the first time since April, and the greatest number of page views since March. It’s even slightly above the twelve-month running average of 1330.6 views per month. There were 870 unique visitors in July, which is almost more than the total number of pages viewed in June. The 870 unique visitors are a fair bit above the twelve-month running average of 822.4 unique visitors per month. By the way, I put together a spreadsheet so I can more easily track twelve-month running averages, as well as averages-per-post.

This offers some information I find interesting. By this I mean it’s information I don’t know how to understand. In July there were 11 posts and, on average, 123.3 views per posting. This is not to say each July post got viewed, on average, 123.3 times. It’s that, roughly, every three days there were about 123 pages viewed from my whole catalogue. This average is in line with the twelve-month running average of 121.0 views per posting. It works out to an average 7.1 unique visitors per posting. That’s probably not significantly greater than the 6.7 unique visitors per posting over the previous twelve months.

There were 45 likes given to things in July. That’s down from the previous twelve-month average of 62.3 per month. There were 21 comments in July, basically the twelve-month average of 23.1 comments per month. This is 6.4 likes per posting, compared to the twelve-month average of 8.8. It’s also 3.3 comments per posting, which is basically the twelve-month average of 3.6. Incidentally, my twelve-month average had been 14.3 posts per month. This is helped by some A to Z sequences, which I haven’t yet done this year.

There may be something else helping my readership. Because of scheduling needs I’d put some of my big Reading the Comics posts to publish on Tuesday, rather than Sunday. I did read a site claiming that WordPress posts got the most readership when posted Tuesday through Thursday. I do not know the methodology of this research. Nor whether it’s still valid, since the post also talked about when Google+ posts were most effective. But this is the only thing I did all that different in July. Maybe I’ll keep that going another month or two and see if it makes a noticeable difference.

192 different posts got at least one page view in July. That’s up from the 158 in June and 163 in May. I don’t have twelve-month running averages for this. But here were the most popular posts:

I’d had 99 posts get a single view each, by the way.

Mercator-style map of the world with the United States in darkest red, and pink regions for most of North America, Europe, and South Asia, plus Australia and a about half of South America.
I admit I’m disappointed to not have any Iceland readers, but since my dad visited Iceland in June and not July I suppose that’s to be expected.

WordPress tells me that 64 countries or country-like entities sent me at least a single reader in July. 54 had in June and 61 in May. There were 17 single-reader countries for the second month in a row. There had been 16 in May. The roster of countries? It’s this:

Country Readers
United States 791
Philippines 103
United Kingdom 75
India 64
Canada 37
Australia 34
Italy 18
Brazil 16
Germany 16
Singapore 15
South Africa 15
France 10
Hong Kong SAR China 9
Malaysia 9
Denmark 8
Colombia 7
Ireland 7
Hungary 6
Mexico 6
Pakistan 6
Taiwan 6
Thailand 6
Argentina 5
Spain 5
Sweden 5
Puerto Rico 4
Switzerland 4
United Arab Emirates 4
Finland 3
Greece 3
Kenya 3
Netherlands 3
Nigeria 3
Poland 3
Russia 3
Slovenia 3
Tanzania 3
Ukraine 3
Bangladesh 2
Belgium 2
Ethiopia 2
Japan 2
Norway 2
Slovakia 2
South Korea 2
Sri Lanka 2
Turkey 2
Botswana 1
Burundi 1
China 1
Costa Rica 1
Czech Republic 1
Egypt 1 (*)
European Union 1
Fiji 1
Guam 1
Israel 1 (*)
Latvia 1
Macedonia 1
Nepal 1
New Zealand 1
Saudi Arabia 1
Serbia 1
Vietnam 1 (**)

Egypt and Israel were single-reader countries in June. Vietnam’s been a single-reader country two months running. I’m surprised to have so few New Zealand readers. And I continue to wonder if the Philippines aren’t reading me by some mistake. Again, I’m not one to turn away readers. It’s just that I write a blog here that’s very steeped in contemporary United States culture and I’m surprised anyone else would me relevant.


By the start of August I had published 79 posts on the year, with a total of 77,108 words. 9,656 of those words were published in July. That’s an average of 878 words per post in July. It’s an average 976 words per post for all of 2019 so far. At the start of July my average post for the year had been 992 words.

For 2019 through the start of August I’d recorded 348 likes, an average of 4.4 likes per posting. That’s slightly down from the start of July’s 4.5 likes per posting. There’d been 136 comments recorded, an average of 1.7 comments per posting. That’s an increase from the average 1.5 comments per posting logged at the start of July. But that count includes some pingbacks, the bits where one post refers to another.

As of the start of August I’ve posted 1,281 things to this blog. They had recorded 81,223 page views, from a logged 41,759 unique visitors.

If you’d like to be a regular reader I’d be glad to have you. There’s a “Follow Nebusresearch” button in the upper right corner of this page. Clicking it will add my posts to your WordPress Reader. If you don’t want to read through WordPress, you can use any RSS reader you like. The feed is https://nebusresearch.wordpress.com/feed/ and please use it.

I’m @nebusj on Twitter, and each post gets an announcement there. It also gets announcements of my humor blog’s posts. Those might not be to your taste, but, you don’t know for sure until you read some. And I do at least try to start the month with rabbit pictures.

Reading the Comics, August 3, 2019: Summer Trip Edition


I was away from home most of last week. Comic Strip Master Command was kind and acknowledged this. There wasn’t much for me to discuss. There’s not even many comics too slight to discuss. I thank them for their work in not overloading me. But if you wondered why Sunday’s post was what it was, you now know. I suspect you didn’t wonder.

Mark Anderson’s Andertoons for the 29th of July is a comfortable and familiar face for these Reading the Comics posts. I’m glad to see it. The joke is built on negative numbers, and Wavehead’s right to say this is kind of the reason people hate mathematics. At least, that mathematicians will become comfortable with something that has a clear real-world intuitive meaning, such as that adding things together gets you a bigger thing. And then for good reasons of logic get to counter-intuitive things, such as adding things together to get a lesser thing. Negative numbers might be the first of these intuition-breaking things that people encounter. That or fractions. I encounter stories of people who refuse to accept that, say, \frac16 is smaller than \frac13 , although I’ve never seen it myself.

On the chalkboard, '-3 + -5 = -8'. Wavehead, to teacher: 'So by adding them together we ended up with less than we started with? See, this is why people hate math.'
Mark Anderson’s Andertoons for the 29th of July, 2019. Essays with some mention of Andertoons are common enough, and are at this link.

So why do mathematicians take stuff like “adding” and break it? Convenience, I suppose, is the important reason. Having negative numbers lets us treat “having a quantity” and “lacking a quantity” using the same mechanisms. So that’s nice to have. If we have positive and negative numbers, then we can treat “adding” and “subtracting” using the same mechanisms. That’s nice to do. The trouble is then knowing, like, “if -3 times 4 is greater than -16, is -3 times -4 greater than 16? Or less than? Why?”

Caption: 'Mime over Matter'. Several mimes stand in a science lab, surrounded by beakers and stuff. On the blackboard are mathematical scribblings, including E = mc^2 but mostly gibberish equations.
Jeffrey Caulfield and Brian Ponshock’s Yaffle for the 31st of July, 2019. Fewer essays mention Yaffle, but those that do are at this link.

Jeffrey Caulfield and Brian Ponshock’s Yaffle for the 31st of July uses the blackboard-full-of-mathematics as shorthand for deep thought about topics. The equations don’t mean much of anything, individually or collectively. I’m curious whether Caulfield and Ponshock mean, in the middle there, for that equation to be π times y2 equalling z3, or whether it’s π times x times y2 that is. Doens’t matter either way. It’s just decoration.


And then there are the most marginal comic strips for the week. And if that first Yaffle didn’t count as too marginal to mention, think what that means for the others. Yaffle on the 28th of July features a mention of sudoku as the sort of thing one struggles to solve. Tony Rubino and Gary Markstein’s Daddy’s Home for the 1st of August mentions mathematics as the sort of homework a parent can’t help with. Jim Toomey’s Sherman’s Lagoon for the 2nd sets up a math contest. It’s mentioned as the sort of things the comic strip’s regular cast can’t hope to do.


And there we go. I’m ready now for August. Around Sunday I should have a fresh Reading the Comics page here. And it does seem like I’m missing my other traditional post here, doesn’t it? Have to work on that.

Checking Back in On That 117-Year-Old Roller Coaster


I apologize to people who want to know the most they can about the comic strips of the past week. I’ve not had time to write about them. Part of what has kept me busy is a visit to Lakemont Park, in Altoona, Pennsylvania. The park has had several bad years, including two years in which it did not open at all. But still standing at the park is the oldest-known roller coaster, Leap The Dips.

My first visit to this park, in 2013, among other things gave me a mathematical question to ask. That is, could any of the many pieces of wood in it be original? How many pieces would you expect?

Two parts of the white-painted-wood roller coaster track. In front is the diagonal lift hill. Behind is a basically horizontal track which has a small dip in the middle.
One of the dips of Leap The Dips. These hills are not large ones. The biggest drop is about nine feet; the coaster is a total of 41 feet high at its greatest. The track goes back and forth in a figure-eight layout several times, and in the middle of each ‘straightaway’ leg is a dip like this.

Problems of this form happen all the time. They turn up whenever there’s something which has a small chance of happening, but many chances to happen. In this case, there’s a small chance that any particular piece of wood will need replacing. But there are a lot of pieces of wood, and they might need replacement at any ride inspection. So there’s an obvious answer to how likely it is any piece of wood would survive a century-plus. And, from that, how much of that wood should be original.

And, since this is a probability question, I found reasons not to believe in this answer. These reasons amount to my doubting that the reality is much like the mathematical abstraction. I even found evidence that my doubts were correct.

Covered station for the roller coaster, with 'LEAP THE DIPS' written in what looks like a hand-painted sign hanging from above. Two roller coaster chairs sit by the station.
The station for the Leap The Dips roller coaster, Lakemont Park, Altoona, Pennsylvania. There are two separate cars visible on the tracks by the station. When I last visited there was only one car on the tracks. The cars have a front and a back seat, and while there is a bar to grab hold of, there are no other restraints, which makes the low-speed ride more exciting.

The sad thing to say about revisiting Lakemont Park — well, one is that the park has lost almost all its amusement park rides. It’s got athletic facilities, and a couple miniature golf courses, but besides two wooden and one kiddie roller coaster, and an antique-cars ride, there’s not much left of its long history as an amusement park. But the other thing is that Leap The Dips was closed when I was able to visit. The ride’s under repairs, and seems to be getting painted too. This is sad, but I hope it implies better things soon.

Reading the Comics, July 27, 2019: July 27, 2019 Edition


Last week was busy enough in mathematically themed comic strips. Some of these are pretty slight topics. But including them lets me do one of my favorite things, to have an essay that’s all comics from a single day. It’s my blog, I can use it to amuse myself.

Marcus Hamilton and Ron Ferdinand’s Dennis the Menace for the 27th shows the kind of slightness I’m dealing with. ‘Statistic’ has some nasty connotations in this sense. It suggests something dehumanizing has happened. But the word was maybe doomed to that. The word came about in the 18th century, to describe the systematic collection and study of information about whole populations. They started out being the gathering of information about the state.

Dennis, walking in to his parents: 'Mr Wilson told me not to become a 'statistic'. What church do they go to?'
Marcus Hamilton and Ron Ferdinand’s Dennis the Menace for the 27th of July, 2019. I have a few essays mentioning Dennis the Menace at this link.

But gathering information about a whole state implies, first, that the thing one finds interesting about a people are some measured and recorded aspect. Not the whole of their person-hood. Second, it implies that you wish to approximate the diversity of a whole people with some smaller set of numbers. There’s compelling reasons for a state to want to have statistics. They make it more plausible to know what the state can do. They make it plausible to forecast the results of a policy. Ideally, this encourages wisdom in policy-making. If the tools are used well.

Val, at the store: 'I admit, change is hard. Nobody really *likes* change. But we all have to know how to deal with it.' Cashier, fumbling over work: 'But they didn't *teach* us this in math class.'
Jan Eliot’s Stone Soup Classics for the 27th of July, 2019. The comic originally ran the 18th of September, 1999. Stone Soup has joined those comic strips which are offer only new material on Sundays. However, GoComics offers both the current-syndication-offering and reprints of the strip from its beginning, this “Classics” run. Essays mentioning either current Stone Strip comics or their twenty-year-old reprints are at this link. Or at least they will be: it turns out this is a new tag. I would have sworn I’d discussed this comic before.

Jan Eliot’s Stone Soup Classics for the 27th is the slightest of the comic strips I’m featuring this week. Really it should have been just a mention, but I wanted to have at least three comics shown for today’s essay. Making and counting change is constantly held up as the supreme purpose of teaching arithmetic. This though most any shop has a cash register that will calculate change faster and more accurately than even someone skilled in arithmetic will. I understand the crankiness of people who give the cashier $15.13 for their $12.38 bill, and get the thirteen cents handed back to them before it’s rung up. It’s not evidence that civilization is collapsing. It’s loose change.

Thatababay drawing on figures: Circular. A circle with an ice skater drifting inside it. Rectangular: soccer player kicking a ball to a net at the right edge of the field. Triangular: frame and figure drawn underneath so it's a person hang-gliding. Tubular: skateboarder on top.
Paul Trap’s Thatababy for the 27th of July, 2019. This is another of those comics that wants to be the next Andertoons. Essays featuring Thatababy in their discussion are here.

Paul Trap’s Thatababy for the 27th continues the strip’s thread of turning geometry figures into jokes. This one is less useful than the comic featured Tuesday, which might help one remember what a scalene triangle or a rhombus looks like. Still might be fun.


And with that, last week’s mathematically-themed comic strips are fully discussed. This week’s comics will get discussion at an essay linked from here. Please visit soon and we’ll see what I have to say, and about what.

Reading the Comics, July 26, 2019: Children With Mathematics Edition


Three of the strips I have for this installment feature kids around mathematics talk. That’s enough for a theme name.

Gary Delainey and Gerry Rasmussen’s Betty for the 23rd is a strip about luck. It’s easy to form the superstitious view that you have a finite amount of luck, or that you have good and bad lucks which offset each other. It feels like it. If you haven’t felt like it, then consider that time you got an unexpected $200, hours before your car’s alternator died.

If events are independent, though, that’s just not so. Whether you win $600 in the lottery this week has no effect on whether you win any next week. Similarly whether you’re struck by lightning should have no effect on whether you’re struck again.

Betty: 'We didn't use up our luck winning $600 in the lottery!' Bub: 'You don't think so? Shorty's brother got hit by lightning and lived. The second time, he also lived, but it ruined his truck.' Betty: 'I don't know how to respond to that.' Bub: 'And the third time ... '
Gary Delainey and Gerry Rasmussen’s Betty for the 23rd of July, 2019. I thought this might be a new tag, but, no. Other essays mentioning Betty are at this link.

Except that this assumes independence. Even defines independence. This is obvious when you consider that, having won $600, it’s easier to buy an extra twenty dollars in lottery tickets and that does increase your (tiny) chance of winning again. If you’re struck by lightning, perhaps it’s because you tend to be someplace that’s often struck by lightning. Probability is a subtler topic than everyone acknowledges, even when they remember that it is such a subtle topic.

It sure seems like this strip wants to talk about lottery winners struck by lightning, doesn’t it?

Susan: 'What are you so happy about?' Lemont: 'This morning Lionel and I were had breakfast at Pancake-ville. When it came time to calculate a tip I asked 'What's 20% of $22.22' and it told me. It occurred to me, we're living in the future! We have electric cars, drones, instant knowledge at our fingertips ... it's the future I've dreamt of my entire life!' Susan: 'Sigh ... you always did hate math.' Lemont: 'Only in the FUTURE can a man track down his old math teacher on Facebook and gloat.'
Darrin Bell’s Candorville for the 23rd of July, 2019. Essays inspired by Candorville in some way are here.

Darrin Bell’s Candorville for the 23rd jokes about the uselessness of arithmetic in modern society. I’m a bit surprised at Lemont’s glee in not having to work out tips by hand. The character’s usually a bit of a science nerd. But liking science is different from enjoying doing arithmetic. And bad experiences learning mathematics can sour someone on the subject for life. (Which is true of every subject. Compare the number of people who come out of gym class enjoying physical fitness.)

If you need some Internet Old, read the comments at GoComics, which include people offering dire warnings about what you need in case your machine gives the wrong answer. Which is technically true, but for this application? Getting the wrong answer is not an immediately awful affair. Also a lot of cranky complaining about tipping having risen to 20% just because the United States continues its economic punishment of working peoples.

Woman: 'Oh my gosh, you have twins!' Mathematician: 'Yeah. Please meet my sons.' 'Did you give them rhyming names?' 'No.' 'Alliterative names? Are they named for twins from any books?' 'Lady, I'm a mathematician. I think in clear logical terms. None of this froufrou nonsense for my kids.' 'Okay, okay. So their names are?' 'Benjamin and Benjamax.'
Zach Weinersmith’s Saturday Morning Breakfast Cereal for the 25th of July, 2019. Haven’t seen this comic mentioned since two days ago. Essays mentioning some aspect of Saturday Morning Breakfast Cereal should be gathered at this link.

Zach Weinersmith’s Saturday Morning Breakfast Cereal for the 25th is some wordplay. Mathematicians often need to find minimums of things. Or maximums of things. Being able to do one lets you do the other, as you’d expect. If you didn’t expect, think about it a moment, and then you expect it. So min and max are often grouped together.

Thatababy drawing on a Scalene Triangle, scales and eyes added to one. An Octagon: octopus legs added to an octagon. Rhombus: rhombus with wheels, windows, and a driver added to it, and a passenger hailing it down.
Paul Trap’s Thatababy for the 26th of July, 2019. Essays exploring some topic mentioned by Thatababy are here.

Paul Trap’s Thatababy for the 26th is circling around wordplay, turning some common shape names into pictures. This strip might be aimed at mathematics teachers’ doors. I’d certainly accept these as jokes that help someone learn their shapes.


And you know what? I hope to have another Reading the Comics post around Thursday at this link. And that’s not even thinking what I might do for this coming Sunday.

Reading the Comics, July 22, 2019: Mathematics Education Edition


There were a decent number of mathematically-themed comic strips this past week. This figures, because I’ve spent this past week doing a lot of things, and look to be busier this coming week. Nothing to do but jump into it, then.

Jason Chatfield’s Ginger Meggs for the 21st is your usual strip about the student resisting the story problem. Story problems are hard to set. Ideally, they present problems like mathematicians actually do, proposing the finding of something it would be interesting to learn. But it’s hard to find different problems like this. You might be fairly interested in how long it takes a tub filling with water to overflow, but the third problem of this kind is going to look a lot like the first two. And it’s also hard to find problems that allow for no confounding alternate interpretations, like this. Have some sympathy and let us sometimes just give you an equation to solve.

Teacher: 'If there were three cricketeers and one of them got hit in the head with the ball, how many wold be left?' Ginger: 'None!' Teacher: 'Right. And HOW do you figure that?' Ginger: 'Simple, really. True teammates would go to the hospital with him!'
Jason Chatfield’s Ginger Meggs for the 21st of July, 2019. Essays which mention Ginger Meggs are at this link.

Zach Weinersmith’s Saturday Morning Breakfast Cereal for the 21st is a pun built on two technical definitions for “induction”. The one used in mathematics, and logic, is a powerful tool for certain kinds of proof. It’s hard to teach how to set it up correctly, though. It’s a way to prove an infinitely large number of logical propositions, though. Let me call those propositions P1, P2, P3, P4, and so on. Pj for every counting number j. The first step of the proof is showing that some base proposition is true. This is usually some case that’s really easy to do. This is the fun part of a proof by induction, because it feels like you’ve done half the work and it amounts to something like, oh, showing that 1 is a triangular number.

Scientist pointing her finger in someone's face: 'If you object to my conjecture I'll put you inside this coil of wires that'll create electrical eddy currents in your body until you VAPORIZE!'
Zach Weinersmith’s Saturday Morning Breakfast Cereal for the 21st of July, 2019. It’s not quite every Reading the Comics post with some mention of this comic. Those which do explore Saturday Morning Breakfast Cereal are at this link.

The second part is hard. You have to show that whenever Pj is true, this implies that Pj + 1 is also true. This is usually a step full of letters representing numbers rather than anything you can directly visualize with, like, dots on paper. This is usually the hard part. But put those two halves together? And you’ve proven that all your propositions are true. Making things line up like that is so much fun.

On the chalkboard, 4 + 3 = 6. Wavehead, to teacher: 'It's a rough draft.'
Mark Anderson’s Andertoons for the 22nd of July, 2019. It’s not quite every Reading the Comics post with some mention of this comic. Those which do explore Andertoons are at this link.

Mark Anderson’s Andertoons for the 22nd is the Mark Anderson’s Andertoons for the week. It’s again your student trying to get out of not really knowing mathematics in class. Longtime readers will know, though, that I’m fond of rough drafts in mathematics. I think most mathematicians are. If you are doing something you don’t quite understand, then you don’t know how to do it well. It’s worth, in that case, doing an approximation of what you truly want to do. This is for the same reason writers are always advised to write something and then edit later. The rough draft will help you find what you truly want. In thinking about the rough draft, you can get closer to the good draft.

Herb: 'I don't get it, Ezekiel!' Ezekiel: 'What's that, dad?' Herb: 'You can remember every word from the lyrics of that new rap song! Why can't you remember simple mathematics?' Ezekiel, thinking: 'Cause it isn't put to music and played ten times an hour on the radio.'
Stephen Bentley’s Herb and Jamaal rerun for the 22nd of July, 2019. It originally ran sometime in 2014, based on the copyright notice. Essays mentioning Herb and Jamaal in some way are at this link. Also, what’s the cheaper but more fun snark: observing the genericness of “that new rap song” or the slightly out-of-date nature of a kid listening to the radio?

Stephen Bentley’s Herb and Jamaal for the 22nd is one lost on me. I grew up when Schoolhouse Rock was a fun and impossible-to-avoid part of watching Saturday Morning cartoons. So there’s a lot of simple mathematics that I learned by having it put to music and played often.

Still, it’s surprising Herb can’t think of why it might be easier to remember something that’s fun, that’s put to a memory-enhancing tool like music, and repeated often, than it is to remember whether 8 times 7 is 54. Arithmetic gets easier to remember when you notice patterns, and find them delightful. Even fun. It’s a lot like everything else humans put any attention to, that way.


This was a busy week for comic strips. I hope to have another Reading the Comics post around Tuesday, and at this link. There might even be another one this week. Please check back in.

Reading the Comics, July 20, 2019: What Are The Chances Edition


The temperature’s cooled. So let me get to the comics that, Saturday, I thought were substantial enough to get specific discussion. It’s possible I was overestimating how much there was to say about some of these. These are the risks I take.

Paige Braddock’s Jane’s World for the 15th sees Jane’s niece talk about enjoying mathematics. I’m glad to see. You sometimes see comic strip characters who are preposterously good at mathematics. Here I mean Jason and Marcus over in Bill Amend’s FoxTrot. But even they don’t often talk about why mathematics is appealing. There is no one answer for all people. I suspect even for a single person the biggest appeal changes over time. That mathematics seems to offer certainty, though, appeals to many. Deductive logic promises truths that can be known independent of any human failings. (The catch is actually doing a full proof, because that takes way too many boring steps. Mathematicians more often do enough of a prove to convince anyone that the full proof could be produced if needed.)

Alexa: 'I sort of like math.' Jane: 'Hm. You could have a fever.' Alexa: 'No, really. Math is stable, not like emotional stuff or social stuff that's all over the place. Math is comforting. ... Because, in math, there is always a right answer.' Jane: 'Who cares if there's a right answer if I DON'T KNOW WHAT IT IS?' Alexa: 'Aunt Jane, I was talking about me.'
Paige Braddock’s Jane’s World for the 15th of July, 2019. The comic originally ran, if I’m reading the dates right, the 28th of October, 2002. Essays mentioning Jane’s World should appear at this link. I think that so far the only mention would be Sunday’s post, when I pointed out the existence of this storyline.

Alexa also enjoys math for there always being a right answer. Given her age there probably always is. There are mathematical questions for which there is no known right answer. Some of these are questions for which we just don’t know the answer, like, “is there an odd perfect number?” Some of these are more like value judgements, though. Is Euclidean geometry or non-Euclidean geometry more correct? The answer depends on what you want to do. There’s no more a right answer to that question than there is a right answer to “what shall I eat for dinner”.

Jane is disturbed by the idea of there being a right answer that she doesn’t know. She would not be happy to learn about “existence proofs”. This is a kind of proof in which the goal is not to find an answer. It’s just to show that there is an answer. This might seem pointless. But there are problems for which there can’t be an answer. If an answer’s been hard to find, it’s worth checking whether there are answers to find.

Son: 'I heard the chances of winning the lottery are the same as the chances of being hit by lightning!' Father: 'That's probably true. Did you know Uncle Ted was once hit by lightning on the golf course?' Son: 'No kidding? Did he buy a lottery ticket?'
Art Sansom and Chip Sansom’s The Born Loser for the 16th of July, 2019. There are a couple of essays mentioning The Born Loser, gathered at this link.

Art Sansom and Chip Sansom’s The Born Loser for the 16th builds on comparing the probability of winning the lottery to that of being hit by lightning. This comparison’s turned up a couple of times, including in Mister Boffo and The Wandering Melon, when I learned that Peter McCathie had both won the lottery and been hit by lightning.

Fun With Barfly And Schrodinger! Schrodinger: 'The pirate told the sailor he would walk the plank. The pirate explained that it would not happen until the sky had risen high enough in the sky to illuminate the deck. The sailor asked 'Why? Isn't the plank constant?' The pirate replied 'How the h would I know?''
Pab Sungenis’s New Adventures of Queen Victoria for the 17th of July, 2019. I thought I mentioned this strip more than it seems I have. Well, the essays inspired by something in New Adventures of Queen Victoria should be at this link.

Pab Sungenis’s New Adventures of Queen Victoria for the 17th is maybe too marginal for full discussion. It’s just reeling off a physics-major joke. The comedy is from it being a pun: Planck’s Constant is a number important in many quantum mechanics problems. It’s named for Max Planck, one of the pioneers of the field. The constant is represented in symbols as either h or as \hbar . The constant \hbar is equal to \frac{h}{2 \pi} and might be used even more often. It turns out \frac{h}{2 \pi} appears all over the place in quantum mechanics, so it’s convenient to write it with fewer symbols. \hbar is maybe properly called the reduced Planck’s constant, although in my physics classes I never encountered anyone calling it “reduced”. We just accepted there were these two Planck’s Constants and trusted context to make clear which one we wanted. It was \hbar . Planck’s Constant made some news among mensuration fans recently. The International Bureau of Weights and Measures chose to fix the value of this constant. This, through various physics truths, thus fixes the mass of the kilogram in terms of physical constants. This is regarded as better than the old method, where we just had a lump of metal that we used as reference.

Weenus: 'What's all the noise? I have work in the morning and I'm trying to sleep.' Eight-ball: 'Lettuce [rabbit] just dropped a slice of toast butter-side-up twenty times in a row!' Next panel, they're racing, dragging Lettuce to a flight to Las Vegas.
Jonathan Lemon’s Rabbits Against Magic for the 17th of July, 2019. This comic is trying to become the next Andertoons. Essays mentioninng Rabbits Against Magic are at this link.

Jonathan Lemon’s Rabbits Against Magic for the 17th is another probability joke. If a dropped piece of toast is equally likely to land butter-side-up or butter-side-down, then it’s quite unlikely to have it turn up the same way twenty times in a row. There’s about one chance in 524,288 of doing it in a string of twenty toast-flips. (That is, of twenty butter-side-up or butter-side-down in a row. If all you want is twenty butter-side-up, then there’s one chance in 1,048,576.) It’s understandable that Eight-Ball would take Lettuce to be quite lucky just now.

But there’s problems with the reasoning. First is the supposition that toast is as likely to fall butter-side-up as butter-side-down. I have a dim recollection of a mid-2000s pop physics book explaining why, given how tall a table usually is, a piece of toast is more likely to make half a turn — to land butter-side-down — before falling. Lettuce isn’t shown anywhere near a table, though. She might be dropping toast from a height that makes butter-side-up more likely. And there’s no reason to suppose that luck in toast-dropping connects to any formal game of chance. Or that her luck would continue to hold: even if she can drop the toast consistently twenty times there’s not much reason to think she could do it twenty-five times, or even twenty-one.

And then there’s this, a trivia that’s flawed but striking. Suppose that all seven billion people in the world have, at some point, tossed a coin at least twenty times. Then there should be seven thousand of them who had the coin turn up tails every single one of the first twenty times they’ve tossed a coin. And, yes, not everyone in the world has touched a coin, much less tossed it twenty times. But there could reasonably be quite a few people who grew up just thinking that every time you toss a coin it comes up tails. That doesn’t mean they’re going to have any luck gambling.


Thanks for waiting for me. The weather looks like I should have my next Reading the Comics post at this link, and on time. I’ll let you know if circumstances change.

Reading the Comics, July 20, 2019: Heat Wave Marginalia Edition


So, it has been hot around here. Extremely hot. Like, hot to the point that there’s nothing to do but form hyperbolic statements about the heat. This does not help anyone feel cooler, but it does help us feel like we’re doing something relevant to the weather. The result is that I haven’t had time to think about my comic strip reading. I’ve been very busy trying to pop my head off and leave it in the freezer. This has not worked. Our refrigerator’s dying and we have a replacement scheduled to arrive this week.

The consequence is that I haven’t had time to write my paragraphs about the comic strips that mention mathematical issues of substance. To not be a complete void, though, let me give you the marginalia. These are the comics that mentioned mathematics in some way so slight that I don’t think them worth further discussion. I’ll get to substantial stuff Tuesday. Thank you.

Tony Rubino and Gary Markstein’s Daddy’s Home for the 15th has a kid doing remarkably well in a mathematics exam. It’s treated as extraordinary. This is the traditional use of mathematics as the hard subject.

Percy Crosby’s Skippy for the 7th of March, 1932, and reprinted the 16th of July has Skippy talk about arithmetic lessons. Here, again, it could be any subject, but mathematics has the reputation for being a subject one wants to avoid.

Jon Rosenberg’s Scenes from a Multiverse rerun for the 17th shows off a girl talking about her father’s ability to help with mathematics homework. There is a theme developing in the past week’s mentions.

Keith Tutt and Daniel Saunders’s Lard’s World Peace Tips for the 17th has a ‘Fake Maths’ textbook, the falseness of it proven by the arithmetic being wrong. So that uses a different part of mathematics’ reputation, that of giving us things we can know are certainly true, or certainly false.


The weather should be much nicer the next few days. Trusting that it is, I’ll have an essay at this link Tuesday with a new Reading the Comics post. Thank you for understanding. It’s quite hard to do anything when it’s so hot you realize your couch is melting.

Reading the Comics, July 13, 2019: Marginal Supplemental Edition


So last week there were only a handful of comic strips which mentioned mathematics in any detail. That is, that brought up some point that I could go on about for a paragraph or so. There were more that had some marginal mathematics content. I gather them here for the interested.

Gordon Bess’s Redeye rerun for the 7th mentions mathematics as the homework that the chief is helping his son with. It could be any subject, but arithmetic is easy to fit into one panel of comic strip. And it’s also easy to establish that the work is on a low level. The comic originally ran the 18th of February, 1973.

Bob Shannon’s Tough Town for the 7th has an appearance by a Rubik’s Cube. I’m always going on about that as a group theory artifact.
Tough Town on the 9th also mentioned algebra as a tough subject for students.

John Allen’s Nest Heads for the 10th mentions sudoku. Also the trouble with accounting.

John McPherson’s Close to Home for the 11th mentions percentages. The joke’s built on doing a meaningless calculation. And a bit of convention, in which the label has been reduced to the point people could mis-read it. You just know this guy would tell the “scanner didn’t pick it up, it must be free” joke if he thought of it that fast.

Paige Braddock’s Jane’s World for the 11th is part of a sequence from 2002 in which Jane concludes the problems in her life came from the introduction of algebra. Her niece is having fun with algebra, a thing I understand. Algebra can be a more playful, explorative kind of mathematics than you get with, like, long division. For some people it’s liberating. This one’s a new tag, so I’m sure to be surprised that I have ever mentioned Jane’s World sometime in the future.

Wiley Miller’s Non Sequitur for the 11th presents a Sphere of Serenity. Or, as Danae’s horse points out, a Cube of Serenity. There are ways that the difference between a sphere and a cube becomes nothing. If the cube and the sphere have infinitely great extent, for example, then there’s no observable difference between the shapes. Or if we use certain definitions of distance then the sphere — as in, the points all an equal distance from a center — can be indistinguishable from a cube. That’s not what the comic is going for.


There were no comic strips with any mathematical content last Saturday, it turns out. There have already been a couple comic strips I think I can discuss. One comic strip, anyway. I should have my essay about it for eager readers on Sunday. Thanks for your patience.

Reading the Comics, July 12, 2019: Ricci Tensor Edition


So a couple days ago I was chatting with a mathematician friend. He mentioned how he was struggling with the Ricci Tensor. Not the definition, not exactly, but its point. What the Ricci Tensor was for, and why it was a useful thing. He wished he knew of a pop mathematics essay about the thing. And this brought, slowly at first, to my mind that I knew of one. I wrote such a pop-mathematics essay about the Ricci Tensor, as part of my 2017 A To Z sequence. In it, I spend several paragraphs admitting that I’m not sure I understand what the Ricci tensor is for, and why it’s a useful thing.

Caption: 'Physics Hypotheses That Are Still on The Table'. The No-Boundary Proposal (illustrated with a wireframe of what looks like an open wine glass). The Weyl Conjecture (illustrated with a wireframe of what looks like a football). The Victoria Principal (illustrated with a tableful of cosmetics).
Daniel Beyer’s Long Story Short for the 11th of July, 2019. Essays inspired by something mentioned in Long Story Short should be at this link.

Daniel Beyer’s Long Story Short for the 11th mentions some physics hypotheses. These are ideas about how the universe might be constructed. Like many such cosmological thoughts they blend into geometry. The no-boundary proposal, also known as the Hartle-Hawking state (for James Hartle and Stephen Hawking), is a hypothesis about the … I want to write “the start of time”. But I am not confident that this doesn’t beg the question. Well, we think we know what we mean by “the start of the universe”. A natural question in mathematical physics is, what was the starting condition? At the first moment that there was anything, what did it look like? And this becomes difficult to answer, difficult to even discuss, because part of the creation of the universe was the creation of spacetime. In this no-boundary proposal, the shape of spacetime at the creation of the universe is such that there just isn’t a “time” dimension at the “moment” of the Big Bang. The metaphor I see reprinted often about this is how there’s not a direction south of the south pole, even though south is otherwise a quite understandable concept on the rest of the Earth. (I agree with this proposal, but I feel like analogy isn’t quite tight enough.)

Still, there are mathematical concepts which seem akin to this. What is the start of the positive numbers, for example? Any positive number you might name has some smaller number we could have picked instead, until we fall out of the positive numbers altogether and into zero. For a mathematical physics concept there’s absolute zero, the coldest temperature there is. But there is no achieving absolute zero. The thermodynamical reasons behind this are hard to argue. (I’m not sure I could put them in a two-thousand-word essay, not the way I write.) It might be that the “moment of the Big Bang” is similarly inaccessible but, at least for the correct observer, incredibly close by.

The Weyl Curvature is a creation of differential geometry. So it is important in relativity, in describing the curve of spacetime. It describes several things that we can think we understand. One is the tidal forces on something moving along a geodesic. Moving along a geodesic is the general-relativity equivalent of moving in a straight line at a constant speed. Tidal forces are those things we remember reading about. They come from the Moon, sometimes the Sun, sometimes from a black hole a theoretical starship is falling into. Another way we are supposed to understand it is that it describes how gravitational waves move through empty space, space which has no other mass in it. I am not sure that this is that understandable, but it feels accessible.

The Weyl tensor describes how the shapes of things change under tidal forces, but it tracks no information about how the volume changes. The Ricci tensor, in contrast, tracks how the volume of a shape changes, but not the shape. Between the Ricci and the Weyl tensors we have all the information about how the shape of spacetime affects the things within it.

Ted Baum, writing to John Baez, offers a great piece of advice in understanding what the Weyl Tensor offers. Baum compares the subject to electricity and magnetism. If one knew all the electric charges and current distributions in space, one would … not quite know what the electromagnetic fields were. This is because there are electromagnetic waves, which exist independently of electric charges and currents. We need to account for those to have a full understanding of electromagnetic fields. So, similarly, the Weyl curvature gives us this for gravity. How is a gravitational field affected by waves, which exist and move independently of some source?

I am not sure that the Weyl Curvature is truly, as the comic strip proposes, a physics hypothesis “still on the table”. It’s certainly something still researched, but that’s because it offers answers to interesting questions. But that’s also surely close enough for the comic strip’s needs.

Elderly man: 'Remember coefficients?' Elderly woman: 'No.' Elderly man: 'Me neither.' Caption: 'Nostalgebra.'
Dave Coverly’s Speed Bump for the 11th of July, 2019. Essays which discuss something that appeared in Speed Bump should be at this link.

Dave Coverly’s Speed Bump for the 11th is a wordplay joke, and I have to admit its marginality. I can’t say it’s false for people who (presumably) don’t work much with coefficients to remember them after a long while. I don’t do much with French verb tenses, so I don’t remember anything about the pluperfect except that it existed. (I have a hazy impression that I liked it, but not an idea why. I think it was something in the auxiliary verb.) Still, this mention of coefficients nearly forms a comic strip synchronicity with Mike Thompson’s Grand Avenue for the 11th, in which a Math Joke allegedly has a mistaken coefficient as its punch line.

Gabby: 'It's craft time here at summer camp.' Michael: 'Finally! An activity that won't hurt my brain. Are we weaving? Painting? Making placemats?' Gabby: 'No. We're making probability flash cards.' Michael: 'The probability of us enjoying that activity? Zero.' Gabby: 'Finally! An answer at math camp that we can get right.'
Mike Thompson’s Grand Avenue for the 12th of July, 2019. The fair number of essays in which I complain about Grand Avenue I gather at this link.

Mike Thompson’s Grand Avenue for the 12th is the one I’m taking as representative for the week, though. The premise has been that Gabby and Michael were sent to Math Camp. They do not want to go to Math Camp. They find mathematics to be a bewildering set of arbitrary and petty rules to accomplish things of no interest to them. From their experience, it’s hard to argue. The comic has, since I started paying attention to it, consistently had mathematics be a chore dropped on them. And not merely from teachers who want them to solve boring story problems. Their grandmother dumps workbooks on them, even in the middle of summer vacation, presenting it as a chore they must do. Most comic strips present mathematics as a thing students would rather not do, and that’s both true enough and a good starting point for jokes. But I don’t remember any that make mathematics look so tedious. Anyway, I highlight this one because of the Math Camp jokes it, and the coefficients mention above, are the most direct mention of some mathematical thing. The rest are along the lines of the strip from the 9th, asserting that the “Math Camp Activity Board” spelled the last word wrong. The joke’s correct but it’s not mathematical.


So I had to put this essay to bed before I could read Saturday’s comics. Were any of them mathematically themed? I may know soon! And were there comic strips with some mention of mathematics, but too slight for me to make a paragraph about? What could be even slighter than the mathematical content of the Speed Bump and the Grand Avenue I did choose to highlight? Please check the Reading the Comics essay I intend to publish Tuesday. I’m curious myself.

Particle Physics Made Hard


A friend was playing with that cute little particle-physics simulator idea I mentioned last week. And encountered a problem. With a little bit of thought, I was able to not solve the problem. But I was able to explain why it was a subtler and more difficult problem than they had realized. These are the moments that make me feel justified calling myself a mathematician.

The proposed simulation was simple enough: imagine a bunch of particles that interact by rules that aren’t necessarily symmetric. Like, the attraction particle A exerts on particle B isn’t the same as what B exerts on A. Or there are multiple species of particles. So (say) red particles are attracted to blue but repelled by green. But green is attracted to red and repelled by blue twice as strongly as red is attracted to blue. Your choice.

Give a mathematician a perfectly good model of something. She’ll have the impulse to try tinkering with it. One reliable way to tinker with it is to change the domain on which it works. If your simulation supposes you have particles moving on the plane, then, what if they were in space instead? Or on the surface of a sphere? Or what if something was strange about the plane? My friend had this idea: what if the particles were moving on the surface of a cube?

And the problem was how to find the shortest distance between two particles on the surface of a cube. The distance matters since most any attraction rule depends on the distance. This may be as simple as “particles more than this distance apart don’t interact in any way”. The obvious approach, or if you prefer the naive approach, is to pretend the cube is a sphere and find distances that way. This doesn’t get it right, not if the two points are on different faces of the cube. If they’re on adjacent faces, ones which share an edge — think the floor and the wall of a room — it seems straightforward enough. My friend got into trouble with points on opposite faces. Think the floor and the ceiling.

This problem was posed (to the public) in January 1905 by Henry Ernest Dudeney. Dudeney was a newspaper columnist with an exhaustive list of mathematical puzzles. A couple of the books collecting them are on Project Gutenberg. The puzzles show their age in spots. Some in language; some in problems that ask to calculate money in pounds-shillings-and-pence. Many of them are chess problems. But many are also still obviously interesting, and worth thinking about. This one, I was able to find, was a variation of The Spider and the Fly, problem 75 in The Canterbury Puzzles:

Inside a rectangular room, measuring 30 feet in length and 12 feet in width and height, a spider is at a point on the middle of one of the end walls, 1 foot from the ceiling, as at A; and a fly is on the opposite wall, 1 foot from the floor in the centre, as shown at B. What is the shortest distance that the spider must crawl in order to reach the fly, which remains stationary? Of course the spider never drops or uses its web, but crawls fairly.

(Also I admire Dudeney’s efficient closing off of the snarky, problem-breaking answer someone was sure to give. It suggests experienced thought about how to pose problems.)

What makes this a puzzle, even a paradox, is that the obvious answer is wrong. At least, what seems like the obvious answer is to start at point A, move to one of the surfaces connecting the spider’s and the fly’s starting points, and from that move to the fly’s surface. But, no: you get a shorter answer by using more surfaces. Going on a path that seems like it wanders more gets you a shorter distance. The solution’s presented here, along with some follow-up problems. In this case, the spider’s shortest path uses five of the six surfaces of the room.

The approach to finding this is an ingenious one. Imagine the room as a box, and unfold it into something flat. Then find the shortest distance on that flat surface. Then fold the box back up. It’s a good trick. It turns out to be useful in many problems. Mathematical physicists often have reason to ponder paths of things on flattenable surfaces like this. Sometimes they’re boxes. Sometimes they’re toruses, the shape of a doughnut. This kind of unfolding often makes questions like “what’s the shortest distance between points” easier to solve.

There are wrinkles to the unfolding. Of course there are. How interesting would it be if there weren’t? The wrinkles amount to this. Imagine you start at the corner of the room, and walk up a wall at a 45 degree angle to the horizon. You’ll get to the far corner eventually, if the room has proportions that allow it. All right. But suppose you walked up at an angle of 30 degrees to the horizon? At an angle of 75 degrees? You’ll wind your way around the walls (and maybe floor and ceiling) some number of times, each path you start with. Probably different numbers of times. Some path will be shortest, and that’s fine. But … like, think about the path that goes along the walls and ceiling and floor three times over. The room, unfolded into a flat panel, has only one floor and one ceiling and each wall once. The straight line you might be walking goes right off the page.

And this is the wrinkle. You might need to tile the room. In a column of blocks (like in Dudeney’s solution) every fourth block might be the floor, with, between any two of them, a ceiling. This is fine, and what’s needed. It can be a bit dizzying to imagine such a state of affairs. But if you’ve ever zoomed a map of the globe out far enough that you see Australia six times over then you’ve understood how this works.

I cannot attest that this has helped my friend in the slightest. I am glad that my friend wanted to think about the surface of the cube. The surface of a dodecahedron would be far, far past my ability to help with.

Reading the Comics, July 2, 2019: Back On Schedule Edition


I hoped I’d get a Reading the Comics post in for Tuesday, and even managed it. With this I’m all caught up to the syndicated comic strips which, last week, brought up some mathematics topic. I’m open for nominations about what to publish here Thursday. Write in quick.

Hilary Price’s Rhymes With Orange for the 30th is a struggling-student joke. And set in summer school, so the comic can be run the last day of June without standing out to its United States audience. It expresses a common anxiety, about that point when mathematics starts using letters. It superficially seems strange that this change worries students. Students surely had encountered problems where some term in an equation was replaced with a blank space and they were expected to find the missing term. This is the same work as using a letter. Still, there are important differences. First is that a blank line (box, circle, whatever) has connotations of “a thing to be filled in”. A letter seems to carry meaning in to the problem, even if it’s just “x marks the spot”. And a letter, as we use it in English, always stands for the same thing (or at least the same set of things). That ‘x’ may be 7 in one problem and 12 in another seems weird. I mean weird even by the standards of English orthography.

Summer School. Student, as the instructor writes a^2 + b^2 != c^2 on the board: 'Math isn't fair. It's numbers, numbers, numbers, then bam! It's letters.'
Hilary Price’s Rhymes With Orange for the 30th of June, 2019. Essays with some mention of Rhymes With Orange should be at this link.

A letter might represent a number whose value we wish to know; it might represent a number whose value we don’t care about. These are different ideas. We usually fall into a convention where numbers we wish to know are more likely x, y, and z, while those we don’t care about are more likely a, b, and c. But even that’s no reliable rule. And there may be several letters in a single equation. It’s one thing to have a single unknown number to deal with. To have two? Three? I don’t blame people fearing they can’t handle that.

Mark Leiknes’s Cow and Boy for the 30th has Billy and Cow pondering the Prisoner’s Dilemma. This is one of the first examples someone encounters in game theory. Game theory sounds like the most fun part of mathematics. It’s the study of situations in which there’s multiple parties following formal rules which allow for gains or losses. This is an abstract description. It means many things fit a mathematician’s idea of a game.

Billy: 'If we're ever arrested for the same crime we should never rat each other out. If we don't rat, then maybe we both go free. If we both rat, we both go to jail. If one rats, then the other goes to jail. But since we can't trust the interro --- ' Cow: 'BUT BOOGER GNOME STOLE THAT STEREO EQUIPMENT FOR HIS PIZZA BOX HOUSE!' Billy: 'YOU THINK THE COPS ARE GONNA BUY THAT?' Booger Gnome, with the stolen equipment: 'THERE'S NO @$#&* OUTLETS?!'
Mark Leiknes’s Cow and Boy rerun for the 30th of June, 2019. The comic strip is long since ended, but hasn’t quite rerun enough times for me to get tired of it. So essays featuring Cow and Boy appear this link. The gnome is a lawn gnome who came to life and … you know, this was a pretty weird comic and I understand why it didn’t make it in the newspapers. Just roll with it.

The Prisoner’s Dilemma is described well enough by Billy. It’s built on two parties, each — separately and without the ability to coordinate — having to make a choice. Both would be better off, under interrogation, to keep quiet and trust that the cops can’t get anything significant on them. But both have the temptation that if they rat out the other, they’ll get off free while their former partner gets screwed. And knowing that their partner has the same temptation. So what would be best for the two of them requires them both doing the thing that maximizes their individual risk. The implication is unsettling: everyone acting in their own best interest is supposed to produce the best possible result for society. And here, for the society of these two accused, it breaks down entirely.

Jason Poland’s Robbie and Bobby for the 1st is a rerun. I discussed it last time it appeared, in November 2016, which was before I would routinely include the strips under discussion. The strip’s built on wordplay, using the word ‘power’ in its connotations for might and for exponents.

Robbie: 'My opinion letter is really going to make a difference!' Bobby: 'More power to you, Robbie!' Robbie: 'You've been saying that a lot lately ... know what? I *do* feel more powerful! ... Ooh, an exponent!' (A '10' appears over Robbie's typewriter. Bobby grabs it.) Robbie: 'Hey! I earned that!' Bobby: 'You have no clue what I'll do with this power!' Next panel: Bobby's sleeping, with his sleep sound being 'zzzz^{10}'.
Jason Poland’s Robbie and Bobby rerun for the 1st of July, 2019. I think but am not sure that this comic strip has lapsed into eternal reruns. In any case the essays that mention some topic raised by Robbie and Bobby are at this link.

Exponents have been written as numbers in superscript following a base for a long while now. The notation developed over the 17th century. I don’t know why mathematicians settled on superscripts, as opposed to the many other ways a base and an exponent might fit together. It’s a good mnemonic to remember, say, “z raised to the 10th” is z with a raised 10. But I don’t know the etymology of “raised” in a mathematical context well enough. It’s plausible that we say “raised” because that’s what the notation suggests.

Zach Weinersmith’s Saturday Morning Breakfast Cereal for the 2nd argues for the beauty of mathematics as a use for it. It’s presented in a brutal manner, but saying brutal things to kids is a comic motif with history to it. Well, in an existentialist manner, but that gets pretty brutal quickly.

Kids: 'Will we ever use math?' Teacher: 'Of course! Life is an express train headed for oblivion city, and this proof of Pythagoras' theorem is one more pretty thing to contemplate before you pull into the station.' (The diagram is of a large square, with each leg divided into segments of length a and b; inside is a smaller square, connecting the segments within each of the outer square's edges, with the sides of this inner square length c.) Kid: 'I mean, like, will it get me a job?' Teacher: 'It got me this job conducting your express train!'
Zach Weinersmith’s Saturday Morning Breakfast Cereal for the 2nd of July, 2019. This one doesn’t appear in every Reading the Comics essay, so you can find my discussions inspired by Saturday Morning Breakfast Cereal at this link.

The proof of the Pythagorean Theorem is one of the very many known to humanity. This one is among the family of proofs that are wordless. At least nearly wordless. You can get from here to a^2 + b^2 = c^2 with very little prompting. If you do need prompting, it’s this: there are two expressions for how much area of the square with sides a-plus-b. One of these expressions uses only terms of a and b. The other expression uses terms of a, b, and c. If this doesn’t get a bit of a grin out of you, don’t worry. There’s, like, 2,037 other proofs we already know about. We might ask whether we need quite so many proofs of the Pythagorean theorem. It doesn’t seem to be under serious question most of the time.


And then a couple comic strips last week just mentioned mathematics. Morrie Turner’s Wee Pals for the 1st of July has the kids trying to understand their mathematics homework. Could have been anything. Mike Thompson’s Grand Avenue for the 5th started a sequence with the kids at Math Camp. The comic is trying quite hard to get me riled up. So far it’s been the kids agreeing that mathematics is the worst, and has left things at that. Hrmph.


Whether or not I have something for Thursday, by Sunday I should have anotherReading the Comics post. It, as well as my back catalogue of these essays, should be at this link. Thanks for worrying about me.

Reading the Comics, June 29, 2019: Pacing Edition


These are the last of the comics from the final full week of June. Ordinarily I’d have run this on Tuesday or Thursday of last week. But I also had my monthly readership-report post and that bit about a particle physics simulator also to post. It better fit a posting schedule of something every two or three days to move this to Sunday. This is what I tell myself is the rationale for not writing things up faster.

Ernie Bushmiller’s Nancy Classics for the 27th uses arithmetic as an economical way to demonstrate intelligence. At least, the ability to do arithmetic is used as proof of intelligence. Which shouldn’t surprise. The conventional appreciation for Ernie Bushmiller is of his skill at efficiently communicating the ideas needed for a joke. That said, it’s a bit surprising Sluggo asks the dog “six times six divided by two”; if it were just showing any ability at arithmetic “one plus one” or “two plus two” would do. But “six times six divided by two” has the advantage of being a bit complicated. That is, it’s reasonable Sluggo wouldn’t know it right away, and would see it as something only the brainiest would. But it’s not so complicated that Sluggo wouldn’t plausibly know the question.

Nancy, to Sluggo, pointing to a wrinkled elderly man: 'That's Professor Stroodle, the big scientist. What a brain he must have! Look at that wrinkled brow --- that means lots and lots of brains.' Sluggo 'Wrinkles means brains?' Nancy: 'Sure!' Sluggo, interrogating a wrinkly-faced dog, to Nancy's surprise: 'What's six times six divided by two?'
Ernie Bushmiller’s Nancy Classics for the 27th of June, 2019. It originally ran the 21st of September, 1949. Essays inspired by something in Nancy, either the Ernie Bushmiller classics or the Olivia Jaimes modern ones, should appear at this link. I’m not going to group 1940s Nancy and 2010s Nancy separately.

Eric the Circle for the 28th, this one by AusAGirl, uses “Non-Euclidean” as a way to express weirdness in shape. My first impulse was to say that this wouldn’t really be a non-Euclidean circle. A non-Euclidean geometry has space that’s different from what we’re approximating with sheets of paper or with boxes put in a room. There are some that are familiar, or roughly familiar, such as the geometry of the surface of a planet. But you can draw circles on the surface of a globe. They don’t look like this mooshy T-circle. They look like … circles. Their weirdness comes in other ways, like how the circumference is not π times the diameter.

On reflection, I’m being too harsh. What makes a space non-Euclidean is … well, many things. One that’s easy to understand is to imagine that the space uses some novel definition for the distance between points. Distance is a great idea. It turns out to be useful, in geometry and in analysis, to use a flexible idea of of what distance is. We can define the distance between things in ways that look just like the Euclidean idea of distance. Or we can define it in other, weirder ways. We can, whatever the distance, define a “circle” as the set of points that are all exactly some distance from a chosen center point. And the appearance of those “circles” can differ.

Caption: Non-Euclidean Eric. The picture is of a sloppy, rounded upside-down-T-shaped figure that looks little like a circle.
Eric the Circle for the 28th of June, 2019, this one by AusAGirl. Essays which build on something mentioned in Eric the Circle should appear at this link.

There are literally infinitely many possible distance functions. But there is a family of them which we use all the time. And the “circles” in those look like … well, at the most extreme, they look like squares. Others will look like rounded squares, or like slightly diamond-shaped circles. I don’t know of any distance function that’s useful that would give us a circle like this picture of Eric. But there surely is one that exists and that’s enough for the joke to be certified factually correct. And that is what’s truly important in a comic strip.

Maeve, sitting awake at night, thinking of a Venn diagram: one balloon is 'What I said', the other is 'What I didn't say', and the overlap is 'What I'll ruminate over in self-recriminating perpetuity'.
Sandra Bell-Lundy’s Between Friends for the 29th of June, 2019. Essays in which I discuss something brought up by Between Friends should be at this link.

Sandra Bell-Lundy’s Between Friends for the 29th is the Venn Diagram joke for the week. Formally, you have to read this diagram charitably for it to parse. If we take the “what” that Maeve says, or doesn’t say, to be particular sentences, then the intersection has to be empty. You can’t both say and not-say a sentence. But it seems to me that any conversation of importance has the things which we choose to say and the things which we choose not to say. And it is so difficult to get the blend of things said and things unsaid correct. And I realize that the last time Between Friends came up here I was similarly defending the comic’s Venn Diagram use. I’m a sympathetic reader, at least to most comic strips.


And that was the conclusion of comic strips through the 29th of June which mentioned mathematics enough for me to write much about. There were a couple other comics that brought up something or other, though. Wulff and Morgenthaler’s WuMo for the 27th of June has a Rubik’s Cube joke. The traditional Rubik’s Cube has three rows, columns, and layers of cubes. But there’s no reason there can’t be more rows and columns and layers. Back in the 80s there were enough four-by-four-by-four cubes sold that I even had one. Wikipedia tells me the officially licensed cubes have gotten only up to five-by-five-by-five. But that there was a 17-by-17-by-17 cube sold, with prototypes for 22-by-22-by-22 and 33-by-33-by-33 cubes. This seems to me like a great many stickers to peel off and reattach.

And two comic strips did ballistic trajectory calculation jokes. These are great introductory problems for mathematical physics. They’re questions about things people can observe and so have a physical intuition for, and yet involve mathematics that’s not too subtle or baffling. John Rose’s Barney Google and Snuffy Smith mentioned the topic the 28th of June. Doug Savage’s Savage Chickens used it the 28th also, because sometimes comic strips just line up like that.


This and other Reading the Comics posts should be at this link. This includes, I hope, the strips of this past week, that is, the start of July, which should be published Tuesday. Thanks for reading at all.

How June 2019 Treated My Mathematics Blog


The amazing thing to consider is that anyone had anything to do with my mathematics blog in June. Apart from last month’s review-of-my-readership and a post pointing out some stuff I’d written about counting goldfish, all my posts were Reading the Comics. Those are fine, of course. They’re popular and they keep me writing even when I’m feeling burned out. But they’re also reactive pieces; I feel a certain passivity when I write them. What I’m saying is I’m gathering the energies to do a new A To Z sequence and so I’ll be bothering my art supplier soon for some fresh banners and the like.

So in June 2019 I posted nine things, my lowest in a long while. I’m of the unshakable belief that the number of things I post is the biggest factor I can control regarding how much anyone reads my writings. So how did that affect my readership?

Bar chart showing slightly over four years of monthly readership totals, which were generally growing above a thousand readers per month until the last three months when things started declining.
I’m glad I worked out how to look at several years’ worth of statistics at one time, rather than the maybe two years WordPress wants to show by default. It gives such a greater sense of the sweep of history of readership around here, which encourages me to panic that my most popular days are behind me and all I have to look forward to is burnout and the evaporation of my few remaining intersted readers.

911 page views for June, from a reported 595 unique visitors. This is down from May’s 981 page views and 721 visitors for ten posts. And April’s 1,020 views and 668 visitors for twelve posts. This actually implies a slightly improved view-per-post ratio as I publish less stuff. I think this is an artifact of my having a couple things in the back catalogue that always get read, though, regardless of any new material I have.

Still, this is appreciably below the twelve-month average of 1344.4 views. And way below the twelve-month average of 829.6 unique visitors. It’s a bit above the mean views-per-post, at least. Also the mean viewers-per-post. That’s, again, probably an artifact of older posts.

Because, after all, look at what the most popular posts were in June. This includes a three-way-tie for the fifth-most-popular post:

There were 40 ‘likes’ given in June, down from May’s 43 and back to April’s 40. It’s below the twelve-month average of 66.8, though. It’s even below the twelve-month average of likes-per-posting, too. There were eleven comments in June, under May’s twelve and April’s 14. The twelve-month average is 24.7, so, there we go. At least an A To Z offering typically gets people eager to suggest topics.

Incidentally there were 158 posts that got at least one view in June. This apart from the front page which is what the greatest number of people or people-like Internet objects look at. There were 163 posts that got at least one view in May.

54 countries or things like countries. 61 did in May. In June? 57. So that all seems to be holding steady. There were 17 single-reader countries in June, one more than in April and in May. Which all countries were they? These all:

Mercator-style map of the world with the United States in the darkest red, reflecting my readership being greatest in that country. Most of the Americas and Western Europe are in a lighter red, as are India, New Zealand, and Australia. Plus Russia and Japan, somehow, as well as a smattering of other nations.
Victoria II challenge: create this sphere of influence for the United States. Expert level: by 1870.
Country Readers
United States 551
India 50
Philippines 39
United Kingdom 38
Canada 30
Australia 16
Germany 14
Netherlands 14
Singapore 11
Hong Kong SAR China 10
Brazil 9
Malaysia 9
France 7
Italy 7
Finland 6
Spain 6
Sweden 6
Switzerland 6
Denmark 5
Norway 5
Pakistan 5
South Africa 5
Japan 4
Nepal 4
Estonia 3
Indonesia 3
New Zealand 3
Poland 3
Puerto Rico 3
Greece 2
Guam 2
Hungary 2
Ireland 2
Mexico 2
Peru 2
Portugal 2
Russia 2
Slovenia 2
Turkey 2
Ukraine 2
Argentina 1
Bangladesh 1 (*)
Belize 1
Bermuda 1
Bosnia & Herzegovina 1
Chile 1
Côte d’Ivoire 1
Czech Republic 1
Egypt 1
Iraq 1
Israel 1
Mongolia 1
Sri Lanka 1
Taiwan 1 (*)
United Arab Emirates 1
Venezuela 1
Vietnam 1 (*)

Bangladesh, Taiwan, and Venezuela were single-reader countries in May. No other place is on a single-reader streak like that. I seem to be back to being ignored by Scandinavian countries.

The start of July saw my having made 68 posts here this year, for a collective 67,452 words. This is an average of 992 words per post. This was 9,581 words in June. I’m averaging, so far this year, 992 words per post. At the start of June my average was 981 words per post. My average was 953 words per post at the start of May. I, too, would be interested when this implies my average post will exceed all finite numbers of words. I’m not figuring that mess out.

Through the start of July there’ve been a total of 304 likes, an average of 4.5 likes per posting this year. That’s the same number of average likes per posting as the last two months had seen. There were a total of 105 comments recorded, an average of 1.5 comments per posting, once again the same as at the start of June and of May. This means the Insight panel tells me there were 14 comments on the month, while the statistics panel claims there were 11. There was a similar discrepancy in May, when one panel claimed I had 17 comments and another claimed 12. I think this has to reflect pingbacks, one post referencing another.

As of the start of July I’ve posted 1,270 items to this blog. They’ve attracted a total 79,855 page views — I just passed 80,000 hours ago — from 40,879 acknowledged unique visitors. There are probably more unique visitors, but WordPress did not gather those statistics for us the first years of this blog.

If you’d like to be a regular reader of my writings, please add my blog to your RSS reader. Your reading won’t show up in any data I’m able to track. If you would like to follow my writing in a way that I know happens, use the “Follow Nebusresearch” button at the upper right corner of this page.

And on Twitter I’m @Nebusj, and there I post links to every new essay as it gets published. Also I try at the start of each month to post pairs of rabbit pictures. It’s not much of a thing, but it is a thing. I think that well explains what to expect from me as a writer.

A Neat Fake Particle Physics Simulator


A friend sent me this video, after realizing that I had missed an earlier mention of it and thought it weird I never commented on it. And I wanted to pass it on, partly because it’s neat and partly because I haven’t done enough writing about topics besides the comics recently.

Particle Life: A Game Of Life Made Of Particles is, at least in video form, a fascinating little puzzle. The Game of Life referenced is one that anybody reading a pop mathematics blog is likely to know. But here goes. The Game of Life is this iterative process. We look at a grid of points, with each point having one of a small set of possible states. Traditionally, just two. At each iteration we go through every grid location. We might change that state. Whether we do depends on some simple rules. In the original Game of Life it’s (depending on your point of view) two or either three rules. A common variation is to include “mutations”, where a location’s state changes despite what the other rules would dictate. And the fascinating thing is that these very simple rules can yield incredibly complicated and beautiful patterns. It’s a neat mathematical refutation of the idea that life is so complicated that it must take a supernatural force to generate. It turns out that many things following simple rules can produce complicated patterns. We will often call them “unpredictable”, although (unless we do have mutations) they are literally perfectly predictable. They’re just chaotic, with tiny changes in the starting conditions often resulting in huge changes in behavior quickly.

This Particle Life problem is built on similar principles. The model is different. Instead of grid locations there are a cloud of particles. The rules are a handful of laws of attraction-or-repulsion. That is, that each particle exerts a force on all the other particles in the system. This is very like the real physics, of clouds of asteroids or of masses of electrically charged gasses or the like. But, like, a cloud of asteroids has everything following the same rule, everything attracts everything else with an intensity that depends on their distance apart. Masses of charged particles follow two rules, particles attracting or repelling each other with an intensity that depends on their distance apart.

This simulation gets more playful. There can be many kinds of particles. They can follow different and non-physically-realistic rules. Like, a red particle can be attracted to a blue, while a blue particle is repelled by a red. A green particle can be attracted to a red with twice the intensity that a red particle’s attracted to a green. Whatever; set different rules and you create different mock physics.

The result is, as the video shows, particles moving in “unpredictable” ways. Again, here, it’s “unpredictable” in the same way that I couldn’t predict when my birthday will next fall on a Tuesday. That is to say, it’s absolutely predictable; it’s just not obvious before you do the calculations. Still, it’s wonderful watching and tinkering with, if you have time to create some physics simulators. There’s source code for one in C++ that you might use. If you’re looking for little toy projects to write on your own, I suspect this would be a good little project to practice your Lua/LOVE coding, too.

Reading the Comics, June 27, 2019: Closing A Slow Month Edition


Some months stretch my pop-mathematics writing skills, tasking me with finding new insights into the things I thought I understood and new ways to present them. Some months I’ve written about comic strips a lot. This was one of the latter. Here, let me nearly finish writing about the comic strips of June 2019 that had some mathematical content.

Jonathan Lemon’s Rabbits Against Magic for the 23rd is the Venn Diagram meta-joke for the week. Properly speaking, yes, Eight-Ball hasn’t drawn a Venn Diagram here. Representing two sets in a Venn Diagram, by the proper rules, requires two circles with one overlap. Indicating that both sets have the same elements means noting that there are no elements outside the intersection of these circles. One point of a Venn Diagram is showing all the possible logical relations between sets and maybe then marking off the ones that happen to be relevant to the problem. What Eight-Ball is drawing is an Euler Diagram, which has looser requirements. There’s no sense fighting this terminology battle, though. It makes cleaner pictures to draw a Venn Diagram modified to only show the relations that actually exist. If the goal is to communicate information, clarity counts. A joke counts as information.

Eight-Ball, drawing: 'I'm making my first Venn Diagram! See, in the first set I'm including people who like to think they're good at math. And see here, I'm using a second set to show which of those people like Venn diagrams. It's a perfect circle.' (He shows a circle with two small balloons, labelled A and B, stuck off it. Weenus looks to the audience unimpressed.) Weenus: 'Logic isn't really your thing.' Eight-Ball: 'I guess that changes the diagram!'
Jonathan Lemon’s Rabbits Against Magic for the 23rd of June, 2019. Oh, this strip again. You’ve seen Rabbits Against Magic in essays at this link.

Eight-Ball’s propositions are … well, a bit muddled. His first set is “people who like to think they are good at math”. His second set is “which of those people like Venn Diagrams”. This implies the second set can’t be anything but a subset of the first. So this we’d represent as one circle inside another, at least if we allow that there exists at least one person who likes to think they’re good at math, but still doesn’t like Venn Diagrams. It’s fine for the purposes of comic hyperbole to claim there is no such thing, of course, and I don’t quarrel with that.

Why not have the second group be “people who like Venn Diagrams”, without the restriction that they already think they’re good at math? Here I think there is a serious logical constraint. My suspicion is that Venn Diagrams are liked by people who don’t think they’re good at math. Also by people who aren’t good at math. Venn Diagrams are a wonderful tool because they present the relationships of sets in a way that uses our spatial intuitions. They wouldn’t make a good Internet joke format if they were liked only by people who think they’re good at math. Which is why Jonathan Lemon had to write the joke that way. It’s plausible comic hyperbole to say everyone who thinks they’re good at math likes Venn Diagrams. But there are too many people who react to explicit mathematics content with a shudder, but who like Venn Diagram jokes, to make “everyone who likes Venn Diagrams thinks they’re good at math” plausible.

Man In Black: 'Ma'am! Ma'am! I'm from the government. I'm so glad we found you. You're the median citizen!' Woman: 'What?' MIB: 'In terms of retirment savings you're exactly in the middle! Half the country has more than you and half the country has less!' Woman: 'So?" MIB: 'There's an election coming. This is a briefcase containing one million dollars. I need you to deposit it in your bank account and pretend you never saw me.' Newspaper headline: 'MEDIAN AMERICAN IS NOW MILLIONAIRE'. Secondary headline: 'Math scores continue decline'.
Zach Weinersmith’s Saturday Morning Breakfast Cereal for the 23rd of June, 2019. Oh, this strip again. You’ve seen Saturday Morning Breakfast Cereal in essays at this link.

Zach Weinersmith’s Saturday Morning Breakfast Cereal for the 23rd is a lying-with-statistics joke. The median is an average of a data set. It’s “an” average because, in English, we mean several different things by “average”. Translated into mathematics these different things are, really, completely unrelated. The “median” is the midpoint of the ordered list of the data set. So, as the Man In Black says, half the data in the set is below that value, and half is above. This can be a better measure of “average” than the arithmetic mean is. It tells us a slight something about the distribution, about how the data is arranged. Not much, but then, it’s just one number. What do you want? It has an advantage over the arithmetic mean, which is the thing normal people intend when they say “average”. That advantage is that it’s relatively insensitive to outliers. One or two really large, or tiny, data points can throw the mean way off. The classic example we use these days is to look at the average wealth of twenty people in the room. If Bill Gates enters the room, the mean jumps way up. The median? Doesn’t alter much. (Bill Gates is the figure I see used these days, but it could be anyone impossibly wealthy. I imagine there are versions where it’s Jeff Bezos entering the room. I imagine a century ago, the proposition would be to imagine J P Morgan entering the room, except that a century ago he had been dead six years.)

Cook: 'Two cups water, one cup chicken stock.' Chicken the cook holds: 'Ding ding ding!' Cook: 'You know how to do math? What's 4 minus 2?' Chicken: 'Ding ding.' Cook: '3 plus 2?' Chicken dings five times. Cook: 'Something tells me you're worth more as a sideshow attraction than dinner.' [ Later ] Onlooker: 'A poker-playing chicken? He's probably worth a lot of money!' Chicken is wearing the dealer's cap and in front of a pile of chips. Cook, looking over his cards: 'I hope so! I'm down 50 bucks!'
Steve Skelton’s 2 Cows and a Chicken for the 26th of June, 2019. Oh, this strip ag — wait, no. Is this a new tag?. No, but the strip was on hiatus a while. 2 Cows And A Chicken has appeared before, in essays at this link. You know it wasn’t until transcribing this comic for the alt text that I realized the ‘dings’ were Chicken pecking at the pot and not a noise that he was making directly. I don’t know why I would have thought he’d have just been making ‘ding’ noises. Also it was the end of my transcribing when I realized what Chicken was doing.

Steve Skelton’s 2 Cows and a Chicken for the 26th shows off a counting chicken as a wonder. Animals do have some sense of mathematics. We know in some detail how well crows and ravens can count, and do simple arithmetic. This is partly because we know good ways to test crow and raven arithmetic skills. And we’ve come to appreciate their intelligence as deep and surprising. Chickens, to my knowledge, have gotten less study. But I would expect they’ve got skills. If nothing else, I would expect chickens to have a good understanding of the transitive property. This is the rule that if ‘a’ is greater than ‘b’, and ‘b’ is greater than ‘c’, then it follows that ‘a’ is greater than ‘c’. Chickens have a pecking order, and animals with that kind of hierarchy tend to know transitivity. I don’t know that the reasons for that link have been proven, but, c’mon. And animals doing arithmetic, like the cook says, have been good sideshow attractions or performances for a long while. They’ve also been good starts for scientific study, as people try to work out questions like how intelligence formed, and what other ways it might have formed.

Young kid: 'How do you spell 'fifteen'?' Mom: 'F-I-F-T ... ' (Young kid looks distressed.) Mom: 'What? Oh. 1-5.'
Greg Cravens’s The Buckets for the 27th of June, 2019. All right, this one appears kind of middlingly often. The Buckets turns up in essays at this link.

Greg Cravens’s The Buckets for the 27th is a joke about the representation of numbers. Cravens has a good observation here about learning the differences between representations, and of not being able to express just what representation you want. I love Eddie’s horrified face as his mother (Sarah) tries to spell out the word. There’s probably a good exercise to be done in thinking of as many ways to represent fifteen as possible.

Etymologically, “fifteen” has exactly the origin you would say if you were dragged out of a sound sleep by someone demanding the history of the word RIGHT NOW, THERE’S NO TIME TO EXPLAIN. In Old English it was “fiftyne”, with “fif” meaning “five” and “tyne” meaning “ten more than”. This construction, pretty much five-and-ten, has fallen out of favor in English. Once we get past nineteen we more commonly write out, like, “twenty-one” and “thirty-five” and such. The alternate construction, which would be, like, one-and-twenty, or nine-and-sixty, or such, seems to have fallen out of use except as a more poetic way to express the idea. I don’t know why, say, five-and-twenty would have shifted to twenty-five while the equivalent five-and-ten didn’t shift to … teenfive(?). I would make an uninformed guess that words used more commonly tend to be more stable, and we tend to need smaller numbers more than bigger ones.


I’ll have some more comic strips for you later in the week. Before then should be a statistics review, as I figure out whether anyone is reading this blog after a month when I wrote basically nothing. The next Reading the Comics post should be at this link probably on Thursday. Thank you for reading any of this.

Reading the Comics, June 21, 2019: I Have An Anecdote Edition


A couple years back we needed to patch a bunch of weak spots in the roof. We found all the spots that needed shoring up and measured how long they were, and went to buy some wood and get it cut to fit. I turned over the list of sizes and the guy told us we’d have to buy more than one of the standard-size sheets of plywood to do it. I thought, wait, no, that can’t be, and sketched out possible ways to cut the wood and fit pieces together. Finally I concluded that, oh, yes, the guy whose job it was to figure out how much wood was needed for particular tasks knew what he was talking about. His secret? I don’t know. What finally convinced me was adding up the total area of the wood we’d need, and finding that it was more than what one sheet would be.

Dave Blazek’s Loose Parts for the 19th uses a whiteboard full of mathematics as visual shorthand for “some really complicated subject”. It’s a good set of mathematics symbols on the whiteboard. They don’t mean anything in the combination shown, though. It’s just meant to bewilder.

Caption: Chuck flunks out of Lemming University. Class of lemmings; there's a whiteboard full of symbols. Chuck, thinking: 'I'm not following *any* of this.'
Dave Blazek’s Loose Parts for the 19th of June, 2019. When I have something to write about Loose Parts the result should be at this link.

Zach Weinersmith’s Saturday Morning Breakfast Cereal for the 21st is bewildering, unless you know what the mathematics principle the joke intends to present. This is what I’m here for.

The key is the Mover’s claim that he can look at any amount of stuff and tell you whether it fits in the moving bins. Working out something like this is a version of the knapsack problem. The knapsack problem is … well, the problem you imagine it might be, if someone told you “some mathematicians study a thing called the knapsack problem”? That’s about right. Formally, it’s about selecting from a set of things of different value. How hard is it to pick a subset of things with exactly that value? Or find that there is no such subset?

An engineer, a physicists, and a mathematician are roommates moving to a new place. As the mover pulls up the mathematician worries there isn't enough room. The mover reassures them. Mover: 'I been at this 30 years. I can look at any amount of stuff and instantly tell ya if it can fit in the moving bins.' The engineer says ... 'It's obvious it can fit. Anything that doesn't go in the bins can be taped to the roof.' The physicists says ... 'It's obvious it can fit. If it were the density of a neutron star, our stuff would be the size of a baseball.' The mathematician says ... (groveling before the mover) 'PLEASE DON'T HACK MY E-MAIL!'
Zach Weinersmith’s Saturday Morning Breakfast Cereal for the 21st of June, 2019. I don’t always write about this strip, but when I do write about Saturday Morning Breakfast Cereal, the essay should appear here.

Well, in a sense, not hard at all. You can just keep trying combinations. Eventually you’ll either find a set that works, or you’ll try every possibility and find none of them work. This is known as “exhaustion”, and correctly. If there are ten things, there are 3,628,800 possibilities. Then it gets really bad. If there are twenty things, there are 2,432,902,008,176,640,000 possibilities. Finding the one that works? That could take a while.

So being able to tell whether a collection of things can fit within a particular space? That’s a form of the knapsack problem. Being able to always solve that any faster than just “try out every combination until you find one that works”? That would be incredible. The problem is hard. That’s a technical term. It means what you imagine it means, but more precisely.

So why the mathematician’s response? It’s because the problem of hacking the common Internet security algorithms is also hard. (I am discussing here how difficult hacking would be if the algorithm were implemented perfectly. There are many hacking techniques available because of bugs. Programs are not written perfectly. Compilers do not translate them to computer code perfectly. Computers are not built perfectly. These and more flaws make hacking more possible than it should be.) It’s the same kind of hard as this knapsack problem. I mean “the same” more technically than you might imagine. If you had a method to quickly solve this knapsack problem, then, you could use this to break computer encryption quickly. And, it turns out, vice-versa, so at least there’s some fairness to things. So if the the Mover can, truly, always instantly tell whether a set of things fit in the moving bins, then hacking e-mails should be possible to. The Mover would have to team up with a mathematician who studies computational problems like this. I don’t know how to do it, myself. I think about the how to do this and feel lost, myself.

So is the Mover full of it? Let’s put this more nicely. Is he at least unduly optimistic about his claims?

Nah. What makes the knapsack problem hard is that you have to find a solution that quickly finds answers for every possible set of things. But the Mover doesn’t have to deal with that. Most of the stuff is in boxes. It’s in mostly simple polygonal shapes. There’s not, like, 400 million items, each the size of a Cheerio. The Mover may plausibly have never encountered a set of things to move where he couldn’t tell whether it fits.

And, yes, there’s selection bias. Suppose he declared that no, this load had to fit into two vans. But that actually a sufficiently clever arrangement would have let it fit in one. Who would ever know he was wrong? He’d only ever know his intuition was wrong if he declared something would fit in one van and, in fact, it couldn’t.

In class; '8 + 4 + 7 + 5 =' is on the blackboard. Teacher: 'Skippy, will you come up and set down the answer?' Skippy: 'But I don't know it, Miss Larkin.' Teacher: 'Surely, Skippy, you're not going to give up that easily. Come up and put down something at least.' Skippy: 'Yes, Miss Larkin.' (Skippy puts a big '?' on the right-hand-side of the equation.)
Percy Crosby’s Skippy for the 21st of June, 2019. It originally ran, looks like, the 9th of February, 1932. Essays featuring Skippy should be at this link.

Percy Crosby’s Skippy for the 21st is a student-at-the-board problem. It’s using the punch line that “I don’t know” might be a true answer to any problem. There are many real mathematics problems for which nobody really knows an answer.

But Miss Larkin has good advice here. Maybe you don’t know the final answer. But do you know anything? Write it down. It’s good for partial credit, at least. Working out a part of the problem might also be useful, too. Often you can work out how to do a hard problem by looking at a similar but simpler problem. If Skippy is lost at 8 + 4 + 7 + 5, could he do at least 8 + 4 + 7? Could he do 8 + 4? Maybe this wouldn’t help him get to the ultimate answer. Often a difficult problem turns out to be solved by solving a circle of simple problems, that starve out the hard.

Horace in bed, counting sheep jumping a fence: XXXXVII, XXXIX, and then, puttering along in a golf cart instead of leaping the fence, XL.
Samson’s Dark Side of the Horse for the 21st of June, 2019. And I don’t always write about this comic either, but when I do write about Dark Side of the Horse I make an essay that should appear at this link.

Samson’s Dark Side of the Horse for the 21st is the Roman Numerals joke for this time around. I’m not sure this whether this is a repeat. The strip does a lot of Roman Numerals jokes, and counting-sheep jokes.

Our roof patches held up for their need, which was just to last a couple months while we contracted for a replacement roof. And, happily, the roof replacement got done speedily and during a week that did not rain. (Back in grad school the apartment I was in had its roof replaced on a day that, it turns out, would get a spontaneous downpour halfway through. My apartment was on the top floor. This made for an exciting afternoon.)


This wraps up the past week’s comics. There weren’t any that mentioned mathematics more fleetingly than Dark Side of the Horse did. A new Reading the Comics post should be at this link on Sunday. Thank you for reading along.