A biologist is someone who studies living things. A physicist studies moving things. A chemist studies substances. An astronomer studies stars and planets. A geologist studies rocks. mathematicians study patterns.
A pair of odd numbers always add up to an even number. The exterior angles of any polygon, no matter how big or small or irregular, always add up to a full revolution of 360 degrees. The rows of Pascal’s Triangle always add up to a power of 2.
There are so many things I love about my children. One of my favorite qualities is their perpetual wonder.
semicircular rainbows. The full version can indeed be seen when viewed from the air, such as out the window of a plane if your timing is lucky enough!
a choir of raindrops has conspired together to put on a light show so breathtaking and ethereal that if it didn’t just appear in the sky above our heads, we probably wouldn’t believe it.
Mathematicians call these kinds of graphs periodic, since they repeat over and over at consistent intervals of time (“periods”). The actual shape you’re looking at gets the fancy title of sinusoidal wave, sine for short.
The hollow body of the guitar provides a space where the vibrations can echo and amplify.
the beauty of a musical instrument is that you can make it play different notes. On a guitar, the way you do that is by pressing a string down onto one of the bars positioned on the guitar’s neck, which are called frets.
Pressing down on a fret essentially makes the string act as though it were a shorter version of itself—the part that you pluck has a smaller length than if you had left the string untouched. And a shorter string can vibrate up and down faster, while a longer string has to vibrate up and down more slowly.
thicker, heavier strings also move more slowly and so they produce notes with lower pitch/deeper sounds.
Beethoven is known for his astonishing skill in arranging sounds of consonance—like the harmony shown opposite—together with sounds of dissonance, which cause the listener to yearn for a resolution
You can see here that the musical notes in dissonant chords get very close, but never seem to start or stop together at neat intervals. The human ear bristles at such sounds, which is why our musical yearning is actually the unconscious desire for mathematical harmony.
rates of exponential growth, which seemed to have a fixed “cap” (the number e).
exponential growth (or in the case of my cup of tea, exponential decay
law of diminishing returns
Mathematicians call this idea a limit
This number is so important that it gets a special name: e. You can take that to mean “exponential,” or as an abbreviation of the other name it’s been given: Euler’s number (referring to the Swiss mathematician Leonhard Euler).
Pi Day is usually marked on March 14
Here we brandish one of the mathematician’s favorite problemsolving techniques: Tackle a simpler version of the question first, and see if you can observe a pattern or structure that can help you with the harder original question.
Often the easiest way to make a question simpler is to make it smaller. So, let’s start with the smallest this question can possibly be: What if there was just a single chocolate in the box?
e = 2.718281828459045 …
100 ÷ e = 36.7879441171 . . .
phi (as in the Greek letter). Its symbol is φ
The value of phi is exactly equal to (1 + √5) ÷ 2, or approximately 1.6180339887.
The golden rectangle is universally recognized as an aesthetically proportioned figure. bank card, or perhaps a driver’s license
Try your birthday, or any random set of numbers. It doesn’t matter how big or small they are. Every sequence produced like this eventually approaches the golden ratio.
I use a piece of mathematical shorthand in the table on the previous page called a power (it’s also called an index or an exponent—which is where we get the word exponential).
Mathematicians always want to write things in the most efficient way possible, and they often invent all-new symbols and types of notation to allow them to say things more quickly. Multiplication began as a shorthand for repeated addition: When you see 3 × 5, that’s equivalent to seeing 5 + 5 + 5.
Applied mathematics. musicians don’t usually play music because it solves a problem, and most people listen to music because they enjoy it. In mathematical terms, we call this pure mathematics
This round trip, about 15,000 miles long, takes less than a fifth of a second.
the check digit
set of steps (called an algorithm)
if any digits are moved into a different place (e.g., 61021994)— which is called a transposition error
private key encryption
transposition cipher
significant limitations
Just like infantry gave way to cavalry and naval cannons were superseded by cruise missiles, there has been (and still is) a mathematical arms race between the cryptographers trying to keep messages secret and the cryptanalysts who are trying to crack them
Professor Robert Lewand in his book Cryptological Mathematics
mathematicians call a trapdoor function. trapdoors are easy to fall down into but difficult to climb back out of.
what are the prime numbers that give 1,349 when they are multiplied? Not so easy! (The answer is 19 and 71, by the way.) This kind of problem isn’t just hard for our squishy brains; even insanely powerful computers find this problem (called prime factorization) incredibly time-consuming as the numbers get larger and larger. Multiplying is easy, but factoring is hard: It’s a trapdoor.
“Precrime Department” (as in Minority Report)
quincunx
mathematics hones our ability to look at things that appear to be completely different on the outside, and see that they are unified by a single and beautiful pattern.
a bell curve, but mathematicians call it the normal distribution.
“predict the future.” How long will it take for you to arrive at your destination if you are catching a bus from your home into a city center?
While each individual journey is difficult to predict—just like the path of a single ball down the quincunx—the group of all journeys from your suburb into the city cannot help but settle itself inexorably into something resembling the normal distribution. The traffic lights on the journey let some vehicles through and stop others, like the pins sending some balls left and some right. As we take more and more journeys, the times add up like balls at the bottom of the quincunx. This is how online maps build what’s called a probabilistic model for predicting how long a typical journey will last.
But if you knew everything about the coin and how it was launched into the air—its weight, the force with which it is flipped, the humidity of the air and so on—it would truly be possible to know the outcome of the coin flip before it happened.
Train maps show you the relationships between stations (in terms of connections within the network). Mathematical maps show you the relationships between numbers, in terms of how one number can lead to another once certain mathematical operations have been carried out on it.
ILLUMINATI CONFIRMED. Pascal’s Triangle. have a look at what happens if you highlight all the even numbers you can find.
in some parts of Europe they use the gradian, of which there are 400 (not 360) in a full revolution—much nicer to handle with the decimal system. A quarter turn, also known as a right angle, is exactly 100 gradians—which makes a whole lot more sense than the comparatively arbitrary 90 degrees that we’re used to.
Just how many factors does 360 have? A lot! In fact, every number from 1 to 10—except for 7—is a factor of 360 (and 360 is the smallest number in existence to have this quality). If you keep on going, you’ll find that 360 has exactly 24 factors, which is not bad considering the previous number (359) has only 2 factors, and the next number (361) has only 3 factors!
The angle 7.2° is exactly one-fiftieth of a full revolution (360°), which means that if we know the distance between Alexandria and Syene, we just need to multiply it by 50 to get the full circumference of Earth. he came back with an answer of 44,100 kilometers. He was off by a factor of 10 percent
mathematicians probe the unknown not just looking for useful ideas (like the ability to encrypt messages, or the ability to predict the path of the planets and stars), but also out of a desire to see if something unusual or unexpected will appear. And this mathematical field—called number theory—is brimming with the unusual and unexpected.
Why were some elements able to conduct electricity effectively, while others couldn’t? Why did some have high boiling points, while others didn’t? No one had a particularly satisfying answer that made sense of all the data.
In a sea of chaos, there will always be islands of order—as long as the sea is large enough. Ramsey theory. specialized field called graph theory.
the feeling that after so many losses in a row, they were bound to get a win eventually. This is called the gambler’s fallacy.
“scientific proof.” This has been the keystone of human progress since the Enlightenment, and without it we would arguably still be living in the Dark Ages. experimentation and repeatable observations.
While science relies on experiments and history uses sources, mathematics has a different tool: logic.
while it’s impossible to see how much charge is left in a battery at any given time, it is possible to get a rough idea by measuring the rate at which electricity is being dished out by the battery.
Dear Algebra, Please stop asking us to find yourx. She’s never coming back, and don’t ask y.
mathematicians love to “maximize lexical density”—that is, squeeze the most meaning into the smallest space.
division symbol itself, which is actually called an obelus
left-handed boxers reverse this expectation, since they naturally stand in a mirror image of the orthodox stance. This is called the southpaw stance
10 percent—of all people being left-handed.
probabilistic independence or correlation coefficients
“Chocolate eaters live longer, say scientists” or “People who swear are more honest,”
visualize this data, the scatter plot