## Jokebook for the Physical Sciences

One of my hobbies is collecting jokes about science, scientists, and related topics. So here are a few of my favorites, mainly ones about mathematics and physics, though if you know some that aren't here, drop me a line. If you don't mind, I'll annotate them as I go along...

### A mathematician, a physicist and an engineer walk into a bar...

These first few jokes highlight how the students of different disciplines think. They're the ethnic jokes of academia, but unlike most ethnic jokes, the stereotypes expressed have some truth to them.

A mathematician, a physicist, and an engineer are on a train going through Scotland. The engineer sees a black sheep, and says, "Aha! The sheep in Scotland are black!" The physicist shakes his head and says, "Ha! You're wrong! One sheep in Scotland is black!" The mathematician shakes his head sadly and says, "You're both wrong. One sheep in Scotland is black on one side..."

My own personal favorite in this vein is the following...

Several academics are asked to prove the following proposition: "All odd numbers are prime" They responded as follows:

• Mathematician: let's see...3 is prime, and the result follows by mathematical induction.
• Physicist: let's see...3 is prime, 5 is prime, 7 is prime, 9 -- whups, that's composite, 11 is prime, 13 is prime...it's true, since 9 is an experimental error.
• Engineer: let's see...3 is prime, 5 is prime, 7 is prime, 9 is prime, 11 is prime...
• Computer Scientist: let's see...3 is prime, 3 is prime, 3 is prime...
• Economist: let's see...2 is prime, 4 is prime, 6 is prime...

"Hey!" say the engineers. All right, let's be fair to the engineers. Unlike economists, they actually produce things that work. There's supposedly a natural antipathy of engineers towards mathematicians, and vice versa, though I suspect this exists more in the minds of those who are neither than in the actual practitioners of either art. Thanks to the mathematicians, the engineers can practice their art with a bit more precision than could the Romans; thanks to the engineers, the mathematicians can do more than draw circles in the sand and have slaves laboriously copy manuscripts. Still, the contrast between the "theoretical" mathematician and the highly "practical" engineer makes for some great jokes...

A mathematician and an engineer were sitting in a room with a beautiful member of the appropriate sex on the other. Before either can make a move, the Voice of God comes down, and proclaims "At the end of each minute, you may move only half the remaining distance between you and the other side!" A lightning bolt strikes the ground in front of the two to show that God means business.

Immediately the engineer leaps up, crosses half the distance, waits a minute, crosses another quarter, waits a minute, and so on. After a few minutes, the mathematician calls out, "Why are you bothering? You'll never reach the other side!" The engineer calls back, confidently, "Ah, but pretty soon I'll be close enough!"

Okay, so it's not much of a joke, but it's one of the few I know where the engineer gets the better of the mathematician. Granted, this may have something to do with the fact that I know more mathematicians than engineers. I submit the following

A mathematician will call an infinite series convergent if its terms go to zero. A physicist will call it convergent if the first term is finite.

How can you say that?, you ask, as one of the things that's drilled into the heads of every student who learns about infinite series is that even if the terms go to zero, the series does not necessarily converge. My first line of defense is, "Well, it's only a joke..", though that doesn't sit well with a lot of people, especially mathematicians. A better line of defense is that the modern notion of convergence is just that: modern. During the 18th century, series like the harmonic series were called convergent, though it was well known that its sum was infinite.

Incidentally, Poincare also makes the distinction between convergence, in the sense of a mathematician, and in the sense of a physicist or astronomer, and it is almost the same distinction as above, at least with respect to the physicists.

A mathematician, a physicist, and an engineer were in a hotel for a convention. Then, in the middle of the night for no apparent reason, a fire breaks out in the engineer's wastebasket. The engineer rushes over to the bathroom, empties out the ice bucket, fills it with water and pours it into the trash can, dousing the fire. Satisfied that the problem was solved, the engineer goes back to sleep.

Shortly thereafter, a fire broke out in the physicist's wastebasket. The physicist rushes to the bathroom, whips out his calculator, frantically does a few computations, pulls out a cup, fills it to a precisely measured level, and rushes back to the wastebasket, pouring the water onto the fire. As the last drop hits the flame, the fire goes out. Satisfied that the problem was solved, the physicist goes back to sleep.

Finally, a fire breaks out in the mathematician's room. The mathematician rushes to the bathroom, sees the ice bucket, sees a cup, sees the water faucet. Satisfied that the problem could be solved, he goes back to sleep.

A quote I have been unable to track down with certainty is the following toast: "To pure mathematics! May it never be of any use to any one!" It appeared in a New Yorker cartoon some years ago, but it seems to be older than that.

Actually, some of the best jokes just involve physicists and mathematicians. Here's another in the same vein:

A mathematician and a physicist were arguing over whose field of study was better. They decided to settle the argument by posing questions. The mathematician went first, and posed a complicated mathematical problem. With a great deal of effort, several books of mathematical tables and techniques, and a few hours, the physicist gave the solved problem to the mathematician, who was duly impressed.

"All right, my turn. Here's the problem: you have a pot of water on the stove, at 60 F. You want to heat it up to 70 F. What do you do?" The mathematician replied, "Oh, that's easy. You turn the stove on. Fourier's equations govern how heat transfers from the stove to the pot, and you can solve them numerically to find out how long it takes for the water to reach 70 F." The physicist then asks, "All right, so what if the water's at 65 F?"

"Oh, that's even easier. You take the pot of water, stick it in the refrigerator until it cools down to 60 F, and then it simplifies to the previous problem!"

At its simplest, the joke is represented by the following:

Q: How many mathematicians does it take to screw in a light bulb?

A: One. He gives it to seven Lithuanians, and reduces it to the previous joke.

### Mathematicians

You can find aleph-one bottles of beer on the wall elsewhere. But here are a few jokes just about mathematicians and their antics.

A famous mathematical puzzle problem involves the following: two trains on the same track begin a mile apart and head towards each other at 60 miles an hour. A fly on one train flies at 120 mph to the other train, and when it lands there, it flies back to the other train, and so on, flying back and forth between the two trains until it gets squashed in the middle. How far does the fly travel?

A student once asked the great mathematician John von Neumann the above problem. von Neumann thought about it a moment and said, "One mile", the correct answer. "You know, Professor von Neumann, most people don't realize that the problem's really easy to figure out: the trains meet in half a minute, and the fly can travel 1 mile in half a minute. They think they have to add up the infinite series to find out how far the fly travels!" von Neumann looked stunned and after a pause said, "But that's how I did it."

Okay, so now you know the answer to the puzzle, and the easy way to solve it. (Extra credit question: which way does the fly face at the end?). Here's another one that highlights the bane of the mathematics student: the phrase "it is obvious that..." First, a bit of historical humor, somewhat related to my thesis:

Laplace's Mecanique Celeste, an enormous five volume tome on just about everything you ever wanted to know about celestial mechanics, was first translated into the English language by Nathaniel Bowditch. Though others did it before him, Laplace was notorious for leaving length demonstrations to the reader, usually preceded with "C'est visible que.." (It is obvious that..). Bowditch meticulously filled in all the gaps, but before long he grew to dread those words, for he knew that when he saw them, he was in for a lengthy bit of derivation before what Laplace claimed was obvious was, in fact, obvious.

I had to suffer through not a few of Laplace's (and other's) "it is obvious that.." Now for the fun stuff..

A professor was notorious for leaving complicated demonstrations to the students, with no more than a remark that "It is obvious that..." One day a student interrupted. "Professor, is it really obvious that the second line follows from the first?" The professor looked at the board, wrinkled his brow, paced about the room for a few minutes, then, triumphantly said, "Why yes, it is obvious."

Here's another...

Another professor was notorious for writing very little on the board, verbally describing how to go from derivation to derivation, saying it was as obvious as "Two plus two equals four". One day a group of students approached him, and begged him to write more on the board, so they could follow along. The professor, who didn't realize what he was doing, vowed to do so. The next day, however, he continued to lecture in his ordinary style, leaping from derivation to derivation with nary a mark on the board. "Thus, it is as obvious as two plus two equals four" he concluded. Then he caught the eyes of the students who had approached him earlier, obviously lost in the train of deductions, so he turned to the board and carefully wrote, "2 + 2 = 4".

As you'll see in the physics section, there are lots of stories told about specific physicists. However, there aren't many stories told about specific mathematicians; the von Neumann story is the only one I can think of offhand. To remedy this, I shall use the time-honored comic tradition of taking an old joke, filing off a few serial numbers, and calling it new...

Karl Friedrich Gauss was a child prodigy who later blossomed into the greatest mathematician of the age. When he was in his prime, a young man approached him, asking what he should do to become a great mathematician. "If I was you, I would go back to school, and learn as much of the basics of mathematics as I could before I even thought about producing any original work." The young man was perplexed. "But Herr Gauss! You were publishing important mathematical treatises when you were even younger than I am now." "Ah, " Gauss replied, "but I did so without asking for advice."

Okay, the story is usually told about Mozart, but what's a little repackaging among friends?

Incidentally, Gauss decided to become a mathematician only after long debate; at the age of 19, he was undecided, and leaning towards a career in philology (which today we might call linguitics). Then he made the discovery of the millenium: how to construct a regular 17 sided polygon using only compass and straightedge; it was the first new construction technique to be discovered in almost two thousand years. With a lead like that, Gauss abandoned the study of words for the study of mathematics. Here's another joke about Gauss:

Laplace was once asked by Alexander von Humboldt (a German scientist who, in addition to writing an immensely popular work on science called Kosmos, was also responsible for making mountain climbing a popular sport) who the great mathematician in Germany was. Without hesitation, Laplace said, "Pfaff". "Pfaff?" Humboldt said. "What about Gauss?" "Gauss is the greatest mathematician in the world" was Laplace's reply.

### Physicists

I used to be a physics major, until I discovered I had absolutely no laboratory skills. I still enjoy theoretical physics, and try (and usually fail miserably) to keep up with the fast-growing subject. My favorite joke about physicists (or about a particular physicist, at any rate) is the following....

Wolfgang Pauli, the great Austrian physicist who died much too young, went to heaven. At the gate he was greeted by St. Peter who said "Herr Doktor Pauli! As a reward for your contributions to human understanding of physics, God Himself has consented to let you ask him one question." St. Peter took Pauli to an anteroom, where God awaited Pauli's question. "Lord," Pauli said, "I have only one question: the mass ratio between the proton and the electron. Why 1837 to 1?" Instantly a blackboard appeared, and God began to explain why this fundamental ratio was what it was. Halfway through, Pauli sputtered in exasperation, "Das ist ganz falsch!" ["That's completely wrong!"].

Actually, the version I heard had Pauli asking about the Strong Coupling Constant. Unfortunately, if I used it in a joke, I would be morally bound to cite its actual value, and furthermore to explain what it was. This I would have done...but I couldn't find any references to the Strong Coupling Constant in my library. Anyway, a similar story is told about Einstein...

Einstein's General Theory of Relativity predicts a certain displacement of starlight, caused by a large mass; a solar eclipse in 1919 provided the first opportunity to test the theory. A reporter asked Einstein how he would feel if the observations did not support relativity. "I would then feel very sorry for God, for having designed the universe wrong", Einstein replied.

One of the expeditions to measure the Einsteinian displacement of starlight was headed up by the English physicist Arthur Stanley Eddington. Recently, some doubts have been raised about the validity of Eddington's experiment (though General Relativity itself has been tested under a number of other conditions and has passed with flying colors). Talking about Eddington, though...

A reporter once asked Arthur Stanley Eddington (who was one of the teams who used the eclipse of 1919 to verify general relativity) whether it was true that the theory of relativity was so complicated that, except for Einstein, only two other people in the world could understand it. Eddington sat silently for a moment, his brow furrowed. The reporter, fearful that he had offended Eddington, asked what was wrong. "Oh, nothing. I was just trying to figure out who the other person was."

Here's a recycled joke. but it's one Leon Lederman tells in his book, The God Particle, hence its inclusion here. For those who aren't Jewish, a "brouchah" (I hope I spelled it right) is some sort of a benediction given an inanimate object, to make it permissible for a Jew to use it. (For those who are Jewish, if I've totally messed up the definition and/or spelling of a brouchah, tell me.)

Leon Lederman, having just acquired a brand new particle accelerator, and, to make absolutely sure nothing would go wrong, wanted to get a brouchah for it. First, he approached an Orthodox Rabbi."Teacher", Lederman said, "I want to get a brouchah for my particle accelerator." "What's a particle accelerator?" the rabbi said. Lederman explained, and after some thought, a consultation of the Torah, a few conversations with the other rabbis, the rabbi finally answered, "My son, I am afraid I cannot give a brouchah for such an object. If you are concerned, you shouldn't use it."

Well, that couldn't be had, since Lederman had to use the particle accelerator. Disheartened, but still hopeful, he went to a Conservative Rabbi. "Teacher", he said, " I want to get a brouchah for my particle accelerator." "What's a particle accelerator?" the Rabbi said. Lederman explained, and after some thought, the rabbi said, "My son, I am afraid I cannot give a brouchah for such an object; it goes against every tradition. If it bothers you, don't use it."

Again, this was not a suitable answer. Lederman decided to consult a Reformed rabbi. "Teacher, I have this new particle accelerator." "Oh really?" the rabbi said, and they discussed particle physics for a few minutes before Lederman continued, "What I need to know is if it's all right for a Jew to use it." "Well, of course" said the rabbi. "Then will you please give me a brouchah for it!" And the Reformed rabbi said, "What's a brouchah?"

As I said, it's an old, recycled joke; I've heard it about motorcycles, Christmas trees, and what have you. What's interesting is Lederman's supposed concern with propriety, and the idea that it's best not to chances with the supernatural. Which reminds me...

A reporter went to interview the great Danish physicist Niels Bohr, and was astonished to discover that Bohr had a horseshoe hanging over his desk. "Surely you don't believe, Dr. Bohr, that hanging a horseshoe will bring you good luck!" said the astonished reporter. "No, of course not. But I have been informed that it will bring me good luck whether I believe in it or not."

The philosophical among you might recognize the above as a variation on Pascal's Principle. Then again, you might not...it's arguable.

Bohr, Niels
computer scientists
economists
Eddington, A. S.
Einstein, Albert
electron
Gauss, Karl Friedrich: and advice; and Laplace
hotel fire
infinite series: the fly, mathematician and engineer, convergence
light bulbs
mathematical induction
obvious (in mathematics)
Particle accelerator, brouchah for
Pauli, Wolfgang
prime numbers
relativity (general), and Einstein; and Eddington
sheep in Scotland
von Neumann