Advertise here with Carbon Ads

This site is made possible by member support. ❤️

Big thanks to Arcustech for hosting the site and offering amazing tech support.

When you buy through links on kottke.org, I may earn an affiliate commission. Thanks for supporting the site!

kottke.org. home of fine hypertext products since 1998.

🍔  💀  📸  😭  🕳️  🤠  🎬  🥔

kottke.org posts about mathematics

Stupid calculations

From a new site called Stupid Calculations, here’s what an iPhone consisting of all the iPhone displays ever built would look like plopped down in the midst of Manhattan. Behold the Monophone:

Monophone

I also enjoyed this dicussion of what a distribution of actual cash from Yahoo to Tumblr would be like.

What if Marissa preferred instead to thumb off hundred-dollar bills into an ecstatic crowd of Tumblr owners? Using the stack of hundreds kept handy around the house, I conducted a test that worked out to a rate of 90 bills per minute. It could certainly go faster, but it’s important to make a little flourish with each flick, a self-satisfied grin spread across the face. 90 bills per minute x $100= $9000. $1.1 billion / $9000 per minute = 122,222 minutes or 2037 hours or 84.87 continuous, no-bathroom, no-sleep days.

And what will she be getting for all this generosity? In addition to the office, it buys 175 Six Million Dollar Men; with 175 employees as of May, the acquisition works out to $6,285,714 per employee. That’s $41,904 per pound in livestock terms (175 employees @ an average of 150 lbs= 26,250 lbs total).


Unknown mathematician hits a home run

Yitang Zhang, an unknown mathematician who worked at Subway while trying to find an academic position earlier in his career, has written a paper that makes significant progress towards understanding the twin prime conjecture, “one of mathematics’ oldest problems”.

Editors of prominent mathematics journals are used to fielding grandiose claims from obscure authors, but this paper was different. Written with crystalline clarity and a total command of the topic’s current state of the art, it was evidently a serious piece of work, and the Annals editors decided to put it on the fast track.

Just three weeks later — a blink of an eye compared to the usual pace of mathematics journals — Zhang received the referee report on his paper.

“The main results are of the first rank,” one of the referees wrote. The author had proved “a landmark theorem in the distribution of prime numbers.”

Rumors swept through the mathematics community that a great advance had been made by a researcher no one seemed to know — someone whose talents had been so overlooked after he earned his doctorate in 1992 that he had found it difficult to get an academic job, working for several years as an accountant and even in a Subway sandwich shop.

“Basically, no one knows him,” said Andrew Granville, a number theorist at the Universite de Montreal. “Now, suddenly, he has proved one of the great results in the history of number theory.”

Reminds me of a certain patent clerk and his theories about time and space. History doesn’t repeat itself, but it does rhyme. (via @daveg)

Update: Here’s a good profile of and interview with Zhang.

Erica Klarreich, a Berkeley-based science writer who has a Ph.D. in mathematics and has written about Zhang, says his proof demonstrates the remarkable balance between order and randomness within the prime numbers. “Prime numbers are anything but random — they are completely determined,” Klarreich says. “Nevertheless, they seem to behave in many respects like randomly-sprinkled numbers that eventually display all possible clumps and clusters. Zhang’s work helps to put this conjectured picture of the primes on a solid footing.”

Update: Alec Wilkinson has a profile of Zhang in the Feb 2, 2015 issue of the New Yorker: The Pursuit of Beauty.

Zhang, who also calls himself Tom, had published only one paper, to quiet acclaim, in 2001. In 2010, he was fifty-five. “No mathematician should ever allow himself to forget that mathematics, more than any other art or science, is a young man’s game,” Hardy wrote. He also wrote, “I do not know of an instance of a major mathematical advance initiated by a man past fifty.” Zhang had received a Ph.D. in algebraic geometry from Purdue in 1991. His adviser, T. T. Moh, with whom he parted unhappily, recently wrote a description on his Web site of Zhang as a graduate student: “When I looked into his eyes, I found a disturbing soul, a burning bush, an explorer who wanted to reach the North Pole.” Zhang left Purdue without Moh’s support, and, having published no papers, was unable to find an academic job. He lived, sometimes with friends, in Lexington, Kentucky, where he had occasional work, and in New York City, where he also had friends and occasional work. In Kentucky, he became involved with a group interested in Chinese democracy. Its slogan was “Freedom, Democracy, Rule of Law, and Pluralism.” A member of the group, a chemist in a lab, opened a Subway franchise as a means of raising money. “Since Tom was a genius at numbers,” another member of the group told me, “he was invited to help him.” Zhang kept the books. “Sometimes, if it was busy at the store, I helped with the cash register,” Zhang told me recently. “Even I knew how to make the sandwiches, but I didn’t do it so much.” When Zhang wasn’t working, he would go to the library at the University of Kentucky and read journals in algebraic geometry and number theory. “For years, I didn’t really keep up my dream in mathematics,” he said.

“You must have been unhappy.”

He shrugged. “My life is not always easy,” he said.


The proof “from outer space”

In August of 2012, mathematician Shinichi Mochizuki posted a series of four papers online that purported to prove the ABC Conjecture, “a famed, beguilingly simple number theory problem that had stumped mathematicians for decades”. Then, nothing. Or nearly nothing.

The problem, as many mathematicians were discovering when they flocked to Mochizuki’s website, was that the proof was impossible to read. The first paper, entitled “Inter-universal Teichmuller Theory I: Construction of Hodge Theaters,” starts out by stating that the goal is “to establish an arithmetic version of Teichmuller theory for number fields equipped with an elliptic curve…by applying the theory of semi-graphs of anabelioids, Frobenioids, the etale theta function, and log-shells.”

This is not just gibberish to the average layman. It was gibberish to the math community as well.

“Looking at it, you feel a bit like you might be reading a paper from the future, or from outer space,” wrote Ellenberg on his blog.

But seeming jibberish by a genius might just be solid mathematics, but Mochizuki isn’t doing much to help other mathematicians confirm or refute his assertions. Which raises an interesting point: mathematics isn’t all just logic and truth…there’s a social element to it as well.

“You don’t get to say you’ve proved something if you haven’t explained it,” she says. “A proof is a social construct. If the community doesn’t understand it, you haven’t done your job.”

(via @dunstan)


N Is a Number: A Portrait of Paul Erdos

N Is a Number is an hour-long documentary about Hungarian mathematician Paul Erdős.

Erdős was famously a prolific mathematician who collaborated widely….he coauthored over 1500 papers with 500 different collaborators. He was also a homeless methamphetamine user.


The celebrity marriage duration equation

In 2006, Garth Sundem and John Tierney published an equation in the NY Times that attempted to predict celebrity marriage crackups using a few metrics: age, fame, sexiness, etc. The pair recently modified the equation based on the evidence of the last five years and surprisingly, the equation is simpler.

What went right with them — and wrong with our equation? Garth, a self-professed “uber-geek,” has crunched the numbers and discovered a better way to gauge the toxic effects of celebrity. Whereas the old equation measured fame by counting the millions of Google hits, the new equation uses a ratio of two other measures: the number of mentions in The Times divided by mentions in The National Enquirer.

“This is a major improvement in the equation,” Garth says. “It turns out that overall fame doesn’t matter as much as the flavor of the fame. It’s tabloid fame that dooms you. Sure, Katie Holmes had about 160 Enquirer hits, but she had more than twice as many NYT hits. A high NYT/ENQ ratio also explains why Chelsea Clinton and Kate Middleton have better chances than the Kardashian sisters.”

Garth’s new analysis shows that it’s the wife’s fame that really matters. While the husband’s NYT/ENQ ratio is mildly predictive, the effect is so much weaker than the wife’s that it’s not included in the new equation. Nor are some variables from the old equation, like the number of previous marriages and the age gap between husband and wife.


Richard Feynman, No Ordinary Genius

Now available in its entirety on YouTube, a 95-minute documentary on physicist Richard Feynman called No Ordinary Genius.

The excellent film on Andrew Wiles’ search for the solution to Fermat’s Last Theorem is available as well (watch the first two minutes and you’ll be hooked).


How to find Waldo with Mathematica

Someone asked on Stack Overflow how one might go about finding Waldo using Mathematica and someone replied with a solution.

Here's Waldo

(via mlkshk)


The thing about 998,001 is…

If you divide 1 by the number 998,001, you get a list of all the three digit numbers in order except 998. Like so:

998001

Math! (via mlkshk)


Neat multiplication visualization

According to this YouTube video, Japanese do multiplication by drawing lines like this:

(via ★vuokko)


What’s it like to deeply understand math?

Another Quora gem: an answer to the question “what is it like to have an understanding of very advanced mathematics?”

You are comfortable with feeling like you have no deep understanding of the problem you are studying. Indeed, when you do have a deep understanding, you have solved the problem and it is time to do something else. This makes the total time you spend in life reveling in your mastery of something quite brief. One of the main skills of research scientists of any type is knowing how to work comfortably and productively in a state of confusion.

(via @pomeranian99)


NYC water towers

One of the many reasons to love the wooden water towers found on the tops of NYC buildings is that the structures themselves reveal the math behind how they work.

Water Tower

The distance between the metal bands holding the cylindrical structure together decreases from top to bottom because the pressure the water exerts increases with depth. The top band only needs to fight against the water at the very top of the tower but the bottom bands have to hold the entire volume from bursting out.


Menger sponge built from Post-It notes

Nicholas Rougeux is building an approximation of a Menger sponge, a 3-D fractal shape with no volume and infinite surface area, out of Post-It notes.

Menger sponge Post It

It looks about 90% complete…but as a Menger sponge, can you ever really call it finished? (thx, zach)


Today is pi day

And in celebration, this is my new favorite fact about pi: we have calculated pi out to over 6.4 billion digits but only 39 of them are needed to calculate the circumference of a circle as big as the universe “with a precision comparable to the radius of a hydrogen atom”. (via @santheo)


How much is a planet worth?

Over at Boing Boing, Lee Billings has an interview with Greg Laughlin, an astrophysicist who recently came up with an equation for estimating the value of planets, a sort of Drake equation for cosmic economics.

This equation’s initial purpose, he wrote, was to put meaningful prices on the terrestrial exoplanets that Kepler was bound to discover. But he soon found it could be used equally well to place any planet-even our own-in a context that was simultaneously cosmic and commercial. In essence, you feed Laughlin’s equation some key parameters — a planet’s mass, its estimated temperature, and the age, type, and apparent brightness of its star — and out pops a number that should, Laughlin says, equate to cold, hard cash.

At the time, the exoplanet Gliese 581 c was thought to be the most Earth-like world known beyond our solar system. The equation said it was worth a measly $160. Mars fared better, priced at $14,000. And Earth? Our planet’s value emerged as nearly 5 quadrillion dollars. That’s about 100 times Earth’s yearly GDP, and perhaps, Laughlin thought, not a bad ballpark estimate for the total economic value of our world and the technological civilization it supports.


Mathematical doodling

This is a wonderfully whimsical introduction to doodling by way of graph theory, snakes, Oroborous and mobius strips. Oh, and the Mobiaboros.

(via vulture)


Benoit Mandelbrot, RIP

Nothing in the news media yet, but many folks on Twitter and colleague Nassim Taleb are reporting that the father of fractal geometry is dead at age 85. We’re not there yet, but someday Mandelbrot’s name will be mentioned in the same breath as Einstein’s as a genius who fundamentally shifted our perception of how the world works.

Update: The NY Times has confirmation from Mandelbrot’s family. The cause of death was pancreatic cancer.


Habits of mind

Originally written for mathematics students, this list of useful habits of mind is applicable to nearly anyone doing anything.


Fermat’s Last Theorem

This 45-minute documentary on Andrew Wiles’ proof of Fermat’s Last Theorem is surprisingly powerful and emotional. Give it until 1:45 or so and you’ll want to watch the whole thing. The film is not really about math; it’s about all of those movie trailer cliches — “one man!”, “finds the truth!”, “fights the odds!”, etc. — except that this is actually true and poignant.


Basic rules of arithmetic may be broken

And not just broken but unrepairable without the addition of uncertainty. Gödel’s incompleteness theorems aren’t even the half of it.

With Friedman’s work, it seems Gödel’s delayed triumph has arrived: the final proof that if there is a universal grammar of numbers in which all facets of their behaviour can be expressed, it lies beyond our ken.

But don’t worry…”the most severe implications are philosophical”. Phew?


Monday puzzle time!

Here’s the entire text of a talk given at math, magic, and puzzle gathering (attendees included Stephen Wolfram and John Horton “Game of Life” Conway) by Gary Foshee:

I have two children. One is a boy born on a Tuesday. What is the probability I have two boys?

The first thing you think is “What has Tuesday got to do with it?” Well, it has everything to do with it.

The key word in the puzzle is “probability”, which is not a very well understood term outside of the mathematics community. The full answer is at the end of the article.


The formula for Hollywood movies

After analyzing dozens of Hollywood films, a team of researchers has found evidence that the visual rhythm of movies at the shot level matches a pattern called the 1/f fluctuation, the same pattern that is found in dozens of natually occurring phenomena, including the length of the human attention span.

These results suggest that Hollywood film has become increasingly clustered in packets of shots of similar length. For example, action sequences are typically a cluster of relatively short shots, whereas dialogue sequences (with alternating shots and reverse-shots focused sequentially on the speakers) are likely to be a cluster of longer shots. In this manner and others, film editors and directors have incrementally increased their control over the visual momentum of their narratives, making the relations among shot lengths more coherent over a 70-year span.

Modern action movies are particularly adept at matching the audience’s attention span in this manner. The full paper is available here.


Insanely deep fractal zoom

I was really into fractals in college (I know…) when I was making rave flyers (I know!) for a friend’s parties in Iowa (I know! I know! Shut up already!). Anyway, the thing that I really used to love doing with this fractal application that I had on my computer was zooming in to different parts of the familiar Mandelbrot set as far as I could. I never got very far…between 5 or 6 zooms in, my Packard Bell 486/66 (running Windows 3.11) would buckle under the computational pressure and hang. Therefore, I absolutely love this extremely deep HD zoom into the Mandelbrot set:

Just how deep is this computational rabbit hole?

The final magnification is e.214. Want some perspective? a magnification of e.12 would increase the size of a particle to the same as the earths orbit! e.21 would make a particle look the same size as the milky way and e.42 would be equal to the universe. This zoom smashes all of them all away. If you were “actually” traveling into the fractal your speed would be faster than the speed of light.

After awhile, the self-similarity of the thing is almost too much to bear; I think I went into a coma around 5:00 but snapped to in time for the exciting (but not unexpected) conclusion. Full-screen in a dark room is recommended.

Update: This 46-minute video seems to be the deepest fractal zoom out there right now, with a zoom level of 10^10000.

The magnification factor is so much less in the video above but that one’s more fun/artistic. And 10^10000 is such an absurdly large number1 that there’s no way to think about it in physical terms…the zoom factor from the size of the universe to the smallest measurable distance (the Planck length) is only about 10^60.

  1. But as we’ve previously learned, it’s not actually that large.


Found functions

Photographs of curves found in nature and the graphs and functions that go with them.

Found Functions

(via snarkmarket)


Math for non-experts

Mathematician Steven Strogatz is doing what sounds like a fascinating series of posts on mathematics for adults. From the initial post:

I’ll be writing about the elements of mathematics, from pre-school to grad school, for anyone out there who’d like to have a second chance at the subject — but this time from an adult perspective. It’s not intended to be remedial. The goal is to give you a better feeling for what math is all about and why it’s so enthralling to those who get it.

More subject blogs like this, please. There are lots of art, politics, technology, fashion, economics, typography, photography, and physics blogs out there, but almost none of them appeal to the beginner or interested non-expert. (thx, steve)


The ham sandwich theorem

The ham sandwich theorem is sometimes called ham and cheese sandwich theorem, the pancake theorem, and the Stone-Tukey theorem but not the sandwich theorem.

The ham sandwich theorem is also sometimes referred to as the “ham and cheese sandwich theorem”, again referring to the special case when n = 3 and the three objects are

1. a chunk of ham,
2. a slice of cheese, and
3. two slices of bread (treated as a single disconnected object).

The theorem then states that it is possible to slice the ham and cheese sandwich in half such that each half contains the same amount of bread, cheese, and ham. It is possible to treat the two slices of bread as a single object, because the theorem only requires that the portion on each side of the plane vary continuously as the plane moves through 3-space.

No idea how this is related to the I Cut You Choose conundrum.


Have you seen this fractal?

Circle gasket

Unknown fractal. It’s sort of like a Sierpinski gasket but with circles. (via migurski)

Update: Turns out that this fractal is “the orbit of a circle under a Kleinian group generated by two Mobius transformations”. (thx, david)


Pizza pi

A round pizza with radius ‘z’ and thickness ‘a’ has the volume pi*z*z*a. That and other math jokes are available on Wikipedia. Don’t you love it when people explain jokes:

In this case, DEAD refers to a hexadecimal number (57005 base 10), not the state of being no longer alive.

High larious. (via reddit)


Mathematics at the movies

Sam Arbesman highlights the use of mathematics in movies, including game theory (The Dark Knight), epidemiology (zombie movies), and balance theory (Reservoir Dogs).

If you and someone else hate the same third person, but like each other, balance theory says you’re golden — all three can persist without changing their opinions. On the other hand, if all three of you despise the others, it’s an unstable triad, as well as a wildly common plot point for crime movies. While there are numerous resolutions — one person changes his preference toward another, a relationship tie is cut — another route back to stability, albeit a messy one, is the gunning down of at least one person.

Arbesman has some videos and stills on his web site from the movies mentioned in the article as well as the relevant mathematical materials.


Gambling strategy

A relatively short article on the mathematics of gambling.

Let’s say, for example, you want to bet on one of the highlights of the British sporting calendar, the annual university boat race between old rivals Oxford and Cambridge. One bookie is offering 3 to 1 on Cambridge to win and 1 to 4 on Oxford. But a second bookie disagrees and has Cambridge evens (1 to 1) and Oxford at 1 to 2.

Each bookie has looked after his own back, ensuring that it is impossible for you to bet on both Oxford and Cambridge with him and make a profit regardless of the result. However, if you spread your bets between the two bookies, it is possible to guarantee success (see diagram, for details). Having done the calculations, you place £37.50 on Cambridge with bookie 1 and £100 on Oxford with bookie 2. Whatever the result you make a profit of £12.50.

I say relatively because there are literally millions of pages on the web just about blackjack statistics. For instance, it’s easy to see how you’ll lose money playing blackjack in the long run — card counting aside — by looking at this house edge calculator. The only real advantage to the player occurs with a one-deck shoe and a bunch of other pro-player rules, which I imagine are difficult to find at the casinos. (via big contrarian)


Mathematics in Infinite Jest

Those of you still plugging away at Infinite Summer may not want to read this (i.e. spoilers!), but Brian Barone finished early and found some interesting mathematical themes in the book.

Now, here’s the part that really boggled me: the Consumption/Waste idea is a 1:1 correspondence (something in yields something out), what mathematicians call a linear function. The Parabola idea connects, pretty obviously, with parabolas — now we’re looking at x raised to the power of two. Annular Systems are modeled by circles which are given in analytic geometry by equations with both x^2 and y^2. Limits and Infinity, of course, become necessary in order to find the area of shapes under curves like parabolas and three-dimensional projections of circles.

Whoa. That is a tiny bit mind-blowing…do I really have time for a reread right now? (thx, nick)