Favorite math jokes

[Dason]

Meh. It's been called Fermat's Last Theorem for so long that it should probably just stay that way. Anyhow I don't really care that much about what name goes along with what theorem because typically it tells you nothing about who discovered or proved the theorem. I think there's a humorous 'law' named after this...

Edit: Stigler's Law!

[Diadem]

lternatively, we could call it "Gauss's Theorem," because someday we are going to find out that Gauss proved it at age 10.

In that case we should name it Cauchy's Theorem. Because it seems to be a requirement in mathematics that every theory be named after Cauchy.

[phlip]

Either him or Euler... I think his list is even longer than the one for Cauchy... Actually, all of these pages are pretty ridiculous.

I think I'll call it the Last Euler-Fermat Theorem from now on.

[Monika]

For the final question on an oral exam, a student was asked to find the limit to infinity of the following sequence: I know, I know that you know, I know that you know that I know, I know that you know that I know that you know, ...

Dazzled, all the student could come up with was, "I don't know."

The professor, equally baffled, replied, "Seriously? Come on. It's common knowledge!"

I don't get it.

[phlip]

A hint.

[TheChewanater]

Either him or Euler... I think his list is even longer than the one for Cauchy... Actually, all of these pages are pretty ridiculous.

We should call math "Eularology".

[Monika]

A hint.

Thanks.

[StickFigure206]

[Mike_Bson]

i is being such a hypocrite, considering it is not a rational number.

[luftbahnfahrer]

Here's a joke that I've had a few mathemician friends of mine convinced that this is a good joke:

Why did Bourbaki stop publishing?
Because he realised that Serge Lang was one person.

I understand that 'Bourbaki' was the pseudonym used by a group of French mathematicians that published a series of textbooks in the 1930s and 40s, and that Serge Lang was a member of this group. But why is this joke funny? I just don't get it.

[skullturf]

Serge Lang is known for being an incredibly prolific author of textbooks, despite being only one person. I think the idea of the joke is that the members of Bourbaki were like, "Geez, even though we're a collection of people, we can't compete with that guy Lang!"

[CZeke]

I don't see how this begs the question. Fermat's Last Theorem has been proven, and I see no invalid algebraic steps in this proof.

One would need to find out whether the statement he proved is used somewhere in the proof of Fermat's Last Theorem. I'm no expert on this
(or on any math, at this point), but I heard that Wiles used many results of higher math (things that have only been proven recently), and you would have to check every single one of them for this trivial lemma.

I disagree completely. A proof is a proof. If it relied on anything that wasn't already proven, we couldn't call it that. So if this irrationality of roots of 2 is somehow involved in the proof of FLT, it must also be proven there, or at least an existing proof must be cited.

By the same token, once something is proven, we can use it in other proofs without fear. This problem of "begging the question" (I think what Eebster meant was circular reasoning) only happens if we assume things -- if we show that A implies B and B implies A, and call that a proof of both. This is different. If you use known fact X in a proof of theorem Y, then use theorem Y to prove X again, you haven't done anything invalid. You've just wasted your time, because X was already proven.

Using FLT to prove roots of 2 are irrational is perfectly sound, whether the FLT proof uses that fact or not. The joke is just that it's the mathematical equivalent of shooting a fly with a cannon.

[Dason]

The joke is just that it's the mathematical equivalent of shooting a fly with a cannon.

That sounds like it would still take quite a bit of work.

[CZeke]

Let's say a dead fly, then.

[Eebster the Great]

By the same token, once something is proven, we can use it in other proofs without fear. This problem of "begging the question" (I think what Eebster meant was circular reasoning) only happens if we assume things -- if we show that A implies B and B implies A, and call that a proof of both. This is different. If you use known fact X in a proof of theorem Y, then use theorem Y to prove X again, you haven't done anything invalid. You've just wasted your time, because X was already proven.

The proof of this begs the question because it assumes a much stronger condition to prove a much weaker one. That doesn't mean it isn't "valid" in the sense that the propositions entail the conclusions, but it certainly isn't a useful way to derive new information, either.

It's similar to the following proof that humans need to eat food:

1. All animals need to eat food.
2. Humans are animals.
3. Therefore humans need to eat food.

Technically 1 and 2 are known to be true and do entail 3, but in order to prove 1 in the first place we would have needed to know many things, including 3.

[Kirby]

It's similar to the following proof that humans need to eat food:

1. All animals need to eat food.
2. Humans are animals.
3. Therefore humans need to eat food.

Technically 1 and 2 are known to be true and do entail 3, but in order to prove 1 in the first place we would have needed to know many things, including 3.

Unless, of course, we defined animals as entities that need to eat food.

[Monika]

There are animals that don't eat, like a fly that mates and dies within one day.
Then it is a dead fly and can be shot with a cannon.

[mike-l]

There are animals that don't eat, like a fly that mates and dies within one day.
Then it is a dead fly and can be shot with a cannon.

[nitpick]
Mayfly's are the shortest lived insect, living from 30 minutes to 1 day. But they still eat. Also they exist in larva for months to a year, they just die shortly after hatching.

Any living organism that does anything must consume something, whether it be food or energy (eg light or heat), conservation of energy and all.
[/nitpick]

[Monika]

Maybe it wasn't the flies then, but there was some kind of insect or worm that doesn't eat his whole (short) life time. I think it only applied to the males.

[Eebster the Great]

Maybe it wasn't the flies then, but there was some kind of insect or worm that doesn't eat his whole (short) life time. I think it only applied to the males.

Well obviously it couldn't apply to both genders at all stages of life. :O

But no, I don't think there is anything like what you are imagining. There are, however, some adult insects that do not eat. (Also a great many adult plants.)

[pizzazz]

i is being such a hypocrite, considering it is not a rational number.

True, though both its real and imaginary parts are rational, so maybe it likes rational numbers better than irrational ones.

[Eebster the Great]

i is being such a hypocrite, considering it is not a rational number.

True, though both its real and imaginary parts are rational.

But its argument is transcendental.

[mike-l]

i is being such a hypocrite, considering it is not a rational number.

True, though both its real and imaginary parts are rational.

But its argument is transcendental.

So is -1's

[Kurushimi]

Recent conversation lead me to this

"I'm sure you'll change your mind once you have a look at my degrees."

[CZeke]

The proof of this begs the question --

Stop right there. We agree on everything except your use of this term. Begging the question is the specific logical fallacy of assuming at some point what you're trying to prove. If something's already proven and you're just using it, there's no assumption, so you can't be begging the question.

[phlip]

Right... if you use A to prove B, then use B to prove C, then use C to prove B again, then everything's still valid. Redundant, sure (and indeed that's the joke), but not fallacious.

[Eebster the Great]

Stop right there. We agree on everything except your use of this term. Begging the question is the specific logical fallacy of assuming at some point what you're trying to prove. If something's already proven and you're just using it, there's no assumption, so you can't be begging the question.

This phrase seems to stir more controversy than I care to deal with right now. Suffice it to say that many terms for logical and rhetorical fallacies are frequently used in a less formal sense (cf. "slippery slope"), as they nearly always crop up in informal logic. Whether or not this usage is "correct" is perhaps a different issue.

[Demosthenes]

A woman in a bar tries to pick up a mathematician.
"How old, do you think, am I?" she asks coyly.
"Well - 18 by that fire in your eyes, 19 by that glow on your cheeks, 20 by that radiance of your face, and adding that up is something you can probably do for yourself..."

[Qaanol]

Normal people smoke pot on the way to work.

[joshz]

What's the difference between a mathematician and a philosopher?

Spoiler:

A mathematician only needs some paper, a pencil, and a trash can for their work. A philosopher can do without the trash can.

[Eebster the Great]

Normal people smoke pot on the way to work.

I don't get it.

[phlip]

No, you see, it's a pun... in that if you take the bell curve, and turn it upside-down, it looks kinda like a cooking pot, and then there's another pun on "work", meaning force times distance, which makes it all...

Yeah, I got no idea either.

[Talith]

I'm guessing it's a reference to some notable mathematicians (and other scientists) doing their best work while high. So they smoke weed while working (not sure how many people actually smoke on the way to work.... maybe that's an american thing)

[Qaanol]

Commute with a joint.

[Eebster the Great]

Commute with a joint.

Wait, I still don't get it. Is a "joint" like a "join"?

E: For normal subgroups A and B, A∨B = B∨A, where ∨ represents the join of the lattice of normal subgroups, so I guess that makes sense.

[PM 2Ring]

Representations

According to the standard mathematical formulation of quantum mechanics, quantum observables such as x and p should be represented as self-adjoint operators on some Hilbert space. It is relatively easy to see that two operators satisfying the canonical commutation relations cannot both be bounded. The canonical commutation relations can be made tamer by writing them in terms of the (bounded) unitary operators e^−ikx and e^−iap, which admit finite-dimensional representations as well. The resulting braiding relations for these are the so-called Weyl relations. The uniqueness of the canonical commutation relations between position and momentum is guaranteed by the Stone-von Neumann theorem. The group associated with these commutation relations is called the Heisenberg group.

[mahannes]

This might be to geeky even for this forum, but I came up with a while ago and have had a hard time finding a nerdy enough crowd so I figured I'd try here. =)

A frequentist and a bayesanist walk into a bar. A girl is smiling at the bayesanist as they order drinks. The frequentist says:

"Go flirt with her, you can easily score her."

The bayesanist then walks up to her and talks for a bit, but she turns him down and leaves. Walking back to the frequentist he has a big smile on his face, and the frequentist asks him why he would look so happy, when his flirtation appearently didn't end well. The bayesanist answers:

"According to my calculations, we're making out right now!"

[ConMan]

I was thinking of showing that to some Bayesian friends/coworkers to see if it's funny to them, but I'm having trouble coming up with a suitable prior.

[Dason]

This might be to geeky even for this forum, but I came up with a while ago and have had a hard time finding a nerdy enough crowd so I figured I'd try here. =)

A frequentist and a bayesanist walk into a bar. A girl is smiling at the bayesanist as they order drinks. The frequentist says:

"Go flirt with her, you can easily score her."

The bayesanist then walks up to her and talks for a bit, but she turns him down and leaves. Walking back to the frequentist he has a big smile on his face, and the frequentist asks him why he would look so happy, when his flirtation appearently didn't end well. The bayesanist answers:

"According to my calculations, we're making out right now!"

Sounds like the cheeky bastard used a point mass prior.

(It does tend to make the calculations easier...)

[NathanielJ]

Commute with a joint.

Wait, I still don't get it. Is a "joint" like a "join"?

Presumably it's "a joint" like "adjoint". A normal operator is one that commutes with its adjoint. Hence, the joke. You may now slap your knee.