What Formula Would You Tattoo?

My_Skin_As_A_Cheatsheet asks this potentially painful question: "I have a friend/colleague who is planning on getting a tattoo in the next month or so. She has decided that this tattoo will be a mathematical or statistical formula, and has been scouring the web and books in recent weeks looking for a cool formula to put on her upper back/shoulder. If you could tattoo a single formula, axiom, etc. (from math, statistics, or any other similar field) on you, what would it be and why? Are there any you think are particularly profound or important? Cool symbols are a plus." Do you have a formula that means so much to you that you would get it tattoed onto your skin? If so, please share it with us. Please try to do you best in HTML (and I wish there was MathML support in something other than Mozilla...of course, Slashdot won't accept those tags anyways...yet!).

Comments

Infinity

[cameloid]

1 / 0

Re:Infinity

[Zurk]

or infinite sequences ?
try this one :
https://sourceforge.net/snippet/download.php?typ e= snippet&id=100881

BTW, oo is n/0 technically. :)

Re:Infinity

[math nazi]

wrong: 1/0 is not defined, it's NOT infinity.

P = NP

[Anonymous Coward]

You could tattoo the bold claim that "P = NP". And if it turns out that P != NP, it's easier to add a slash than to remove one.

FLT

[Anonymous Coward]

I kind of like this formulation of Fermat's Last Theorem:

x,y,z>0 and n>2 ==> x^n + y^n != z^n

Re:FLT

[Toliaro]

"I have the most elegant proof of this proposition, but my epidermis is too small to contain it."

Re:To celebrate my MCSE

[cameloid]

I always thought that they were the insidious tentacles of Cthulhu...

Drakes equation

[Anonymous Coward]

It's gotta be Drakes equation: N=R*fs*fp*ne*fl*fi*fc*L

check out http://www.seds.org/~rme/drakeeqn.htm

Good luck with your tattoo!

What you are looking for...

[jdybnis]

is the most beautiful formula in mathamatics

Re:What you are looking for...

[grammar nazi]

Take your pick:

Algebraic fundamental formula: Although Euler's formula is very beautiful, I would opt for, the more algebraic, Lagrange's Theorem...

|G|=|H|[G:H]

Where H is a subgroup of a finite group G. Here is a theorem that is at the very basis of algebra and numbers.

Number thoery cool formula: Another equation that would be good for a tattoo is Hardy and Ramanujan's equation for the number of partitions of a number n, p(n). I will TeX the equation since I can't do it justice with HTML. If you don't use LaTeX, then refer to Number Theory, by George Andrews, p. 150 (it's a Dover book so it's $6.95 and excellent).

p(n)=\frac{1}{2\pi\sqrt{2}}\frac{d}{d n}\left{ \frac{\exp \left( \frac{2\pi}{\sqrt{6}} \sqrt{n-\frac{1}{24}} \right) }{\sqrt{n-\frac{1}{24}}}

An interesting thing about this equation is that it doesn't actually converge. You can make it converge to an answer by replacing the exp with a sinh and remove the 2 in the very first denominator, but Hardy and Ramanujan never figured that out.

Simple Chaotic Formula: One of the simplist equations to display a period 3 orbit, and hence chaotic behavior, is the logistic map:

f( x(n+1) )= 4 x(n) ( 1- x(n) )

I would recommend using subcripts in place of (n) and (n+1).

Fourier Series: Finally, nothing in mathematics is more beautiful and elegant than Fourier series. The following equation is at the heart of the MP3 piracy debate and it is responsible for most video and sound encoding. I don't know any equations for Fast Fourier Transforms, but here's one for the general Fourier series (in complex form, because that makes a better tattoo).

\Phi(x)=\sum^{\infty}_{n=-\infty} c_n e^{in\pi x/l}

For further reading in Fourier series (at an undergraduate level), I recommend Partial Differential Equations, an Introduction by Strauss

This slashdot story has inspired me to get a tattoo!

this one is nice...

[Jose]

e^(pi*i) + 1 = 0

that has always been one of my favourites. (mostly because it brings several important numbers into one small formula)

Re:this one is nice...

[kst]

I have my own version of this one ("+/-" is supposed to be a plus-or-minus symbol):

e^(i*pi) = 0 +/- 5%

Of course, you'll want it in mathematical notation rather than ASCIIfied.

Proof.

[Anonymous Coward]

..as long as you can prove it? ..just post the proof on the back, enlighten those tatooists.

My personal favorite..

[cmowire]

I would tattoo the following:

Integral(E^x) = f(u^n)
Which becomes, when you look at it,
Sex = Fun

That would be my suggestion. ;)

Re:My personal favorite..

[geophile]

Big deal. Leonard Wheat already pointed that out in his 2001 book.

Re:My personal favorite..

[__aasfhc1949]

At the University of Chicago, we altered that and put it on a shirt to read:

The limit as u -> u(c) of the integral(e^x) = 0.

Rajiv Varma

Pre-algebraic Existentialism

[timotten]

Everything comes down to:

x = x

If your friend likes non-sequitors, she might prefer:

x != x

If she's intrigued by Zen, she might like:

x = x != x

Though I suppose a more experienced Zen master would just say:

x

Re:Pre-algebraic Existentialism

[Haeleth]

y?

Several options:

[cperciva]

The most obvious candidate would be e^{i \pi} + 1 = 0. Everyone agrees about the beauty of this formula, and it also has the advantage of compactness.

Another option would be \pi = \sum_{i=0}^{\infty}{(\frac{1}{16})^i(\frac{4}{8i+1 }-\frac{2}{8i+4}-\frac{1}{8i+5}-\frac{1}{8i+6})}. While this dates back only six years, and is rather less compact, it is arguably very beautiful because it relates Pi to the simple polylogarithmic constants.

If you want something statistical, how about \sqrt{\pi} = \int_{-\infty}^{\infty}{e^{-x^2} dx} ?

OTOH, if you have lots of space, the Peano axioms (or, even better, the axioms of ZF set theory) would be really cool...

Re:Several options:

[SnatMandu]

Find a nice compact expression of the Axiom of Choice. One of the most interesting math objects ever. But is it true?

Re:Several options:

[math nazi]

Can an axiom be true or false ?

Re:Several options:

[Schwarzchild]

Axioms are supposed to be obviously true. You have to start Mathematics from somewhere!

If it were a chemical formula...

[Bake]

I'd put my favorite.

CH3CH2OH

Re:Tattoo

[grammar nazi]

Ouch! Normally I'm the grammar nazi, but for this post I'm going to play stick-in-the-mud Nazi.

You're link is to an article that talks about hepititus. You can avoid this 100% by going to a reputable tattoo artist and not a hole in the wall place.

Finally I think that your comment about seeing a psychiatrist is a little overboard. I would hardly refer to a tattoo as currently cool and trendy.

Tattoos have been cool and trendy for hundreds of years now. They are here to stay. Hard mathematics has been accurate and around for hundreds of years. Thus, tattoos of hard mathematics are not a temporary fad.

Okay, my logic isn't 100% sound, but you get the point. Now shove off, pal!

Area

[BSDevil]

I've been looking at some of the suggestions, and most of the /. community have forgotten about two of the most fundamental equations that got us here today:

(pi)r^2 and c^2=a^2+b^2

I don't think that anyone can deny that these two equations form part of the basis for all math, not just modern stuff. While Pythagoras has the advantage of being longer, I'd go with the area formula because it's simple, short (so when you decide that having a math quation on your arm isnt what you want, it'l be easy to remove), and has the added bonus of having the funkiest symbol (with the possible exception of either the sum or integral symbols) in there: pi.

Re:Area

[BSDevil]

Personally, I have no ned to understand how analytic number theory can be used to prove the prime number theory. I'm sure if you showed me the proof, I wouldn't have a clue in hell what it meant. And I would have thought the refernece to the integral symbol (is there a specific name for it?) would be a clue to what the most advanced math I understand is: moderate Calculus (the AB exam, to be precise). I don't know number theory, I don't know waveform equations, and right now, I don'tparticularly care about either of the above (when I'm taught them, I'm sure I will).

And as for pi, I still stand by my beleif that it's one of the funkiest mathematical symbols in common usage that most people understand and recognize. As was said earlier; it's not worth having some hugely complex formula on your shoulder if you have to explain it to everyone that sees your shoulder on a beach. Both of the above formulas I suggested are compact, simple enough for most ppl to understand, and are important.

Re:Area

[dillon_rinker]

As was said earlier; it's not worth having some hugely complex formula on your shoulder if you have to explain it to everyone that sees your shoulder on a beach.

I don't see how this is any different from having a mystic sigil tattooed onto your body. A friend of mine delights in explaining what the eye of Ra is.

The traditional

[Grey]

In peusdoTeX:
\intragel_0^\infinity \Delta\hartsuit dt = 0
Which is loosely:" and in the end the love you take is equal to the love you make"

But personally I prefer Euler ($e^{i\pi}+1=0$) or Fermatewith but my &lt body part&gt is to small for the eligante proof.

Re:The traditional

[LuserOnFire]

Ahh..... Math and a Beatles quote... How sweet!

The old classics

[sohp]

Something simple yet beautiful that isn't new and obscure: F=ma

My choices

[maetenloch]

If I had to pick a mathematical formula to wear for the rest of my life I would probably pick Euler's Formula (e^iPi + 1 = 0) or Maxwell's equations. A distant third would be the formula for the Mandelbrot set (Zn = (Zn-1)^2 + C) with an illustration of course. :-)

Physics and geometric algebra

[Dust Puppy]

Many of the equations of Physics are best described in the language of geometric algebra. An excellent introduction to this language can be found here: http://www.mrao.cam.ac.uk/~clifford/ptIIIcourse/.

In particular, on page 5 of lecture 11, Maxwell's equations (which describe all of electromagnetism - pretty much the entire basis of modern technology and which were the starting point for Einstein's discovery of relativity) in one simple equation: (triangle)F = J.

And don't forget

[cperciva]

\int{\frac{1}{cabin} d(cabin)} = houseboat.

(For those who haven't seen this before, the left side evaluates to log cabin + C.)

Not really a formula, but...

[Quay42]

I've been planning for a while (and this would work for anyone with 8 characters in their last time) to get a tatoo of my last name in binary digits in the form of an 8x8 matrix. Thought this would look damn cool. A tad obscure, but hey.

Re:Not really a formula, but...

[anacron]

Um, That's really bizarre. I have the same plans. Though I picked a meaningfull 8 letter word. "Infinity".

I was even thinking of bar-coding it. I want the 8x8 matrix on my foot. Uber cool. And very few people will get it.

Re:Not really a formula, but...

[Betcour]

That's what the horse said. (very private joke for fellow Ultima fans :)

Re:Not really a formula, but...

[Myrcurial]

I've got a stylized @ that appears to be built with blue cat5 - the bare wires showing out of the tail of the circle with my nick (first three letters) in binary below that - I used all caps to make it easier for people to decode. At this point, there is only one person to have successfully decoded it - a female geek behind me in line at a waterslide thing - the other attemptees - a gang of Novell programmers at Brainshare 99 couldn't figure it out at all.

:)

I got it...

[ajuda]

How about 1+1=3?
It may not be right, but it will catch people's interest.


This message was encrypted with rot-26 cryptography.

Re:I got it...

[paulywog]

ACK!!! Far better choice along the same line would be:

1 + 1 = 11

And this one is actually right!

Re:I got it...

[math nazi]

almost.

Re:Maxwell's Equations

[SEWilco]

"Excuse me, my shoe phone is ringing..."

The Schroedinger Wave Equation

[Alik]

Pretty much everything in quantum mechanics is hiding somewhere in the damn thing, nobody can actually solve it for all cases, and it's complex enough to boggle the minds of 99.9% of mortals (yours truly included).

There's a good example (LaTeX->image) here.

Re:The Schroedinger Wave Equation

[dysprosium]

I too would reccomend the Shcrodinger (there should be an umlaut over the o) equation. Note that it is the "Schrodinger Equation" (no wave). The wave function is the quantity represented by the greek letter psi in the SE. But don't use the form that is linked to above, it's silly (why use a gradient in a 1-d equation? just use d/dx instead). You should replace the x-vector with an r-vector to generalize it to 3 dimensions. Or better yet, use the operator form

H psi = E psi

(H should be bold, it's an operator) which tells us that energy is the eigenvalue of the Hamiltonian. This is the time-independent version, useful for solving static systems (like the infinite square well, or the hydrogen atom).

If you're looking for something a little more theoretical, from the world of mathematics instead of physics, may I reccomend the Generalized Stokes Theorem? Very elegant, and of deep theoretical significance.

It says, integral of omega over d psi = integral of d omega over psi

omega is a differential form, and psi is some region in k-D space. d is the differential operator, so d omega is the differential of the differential form, and d psi is the (k-1)-D boundary of psi.

Okay, I have a quantum mechanics exam tomorrow that I need to go back to studying for. Good luck with the tattoo!

Dysprosium

The big one

[jhines]

e=MC^2

All we are, is whats left after the big bang, if it wasn't for that formula, we wouldn't be.

Re:The big one

[math nazi]

That would make her really look like a dumbass because this equation is usually written as E=mc^2. Of course you can also write it as X=YZ^2 if you like, but then nobody will recognize it.

Re:The big one

[math nazi]

Yes they are common symbols, look:

e is usually not an energy but the elementary charge e=1,602e-19 C. (C stands for Coulomb, the unit of electric charge)

C is usually not the speed of light, but stands for a capacity or conductance.

M is used as symbol for mass, but only if you run out of letters, i.e. you have more than one mass.

If you use the common symbols you don't have to say what each of them stands for because everybody will know it. If you use uncommon symbols you have to explain what they stand for otherwise you will confuse people.

Feynman's Theory of Everything

[Eigenray]

U = 0, where U is the unworldliness, obtained by summing the absolute values (or the squares) of the difference of the two sides of every physics equation.

But seriously, Moebius inversion is pretty cool:
\prod_{n | m} {(\prod_{d | n} {g(d)})^{\mu (\frac{m}{n})} = g(m)
Alternatively,
\sum_{n | m} {(\mu (\frac{m}{n}) \sum_{d | n}{f(d)})} = f(m),
which true for any function from the positive integers to any commutative ring, where \mu is the Moebius function, mu(d) = (-1)^(number of prime factors of d) if d is squarefree, 0 otherwise.

Good lord

[Jethro]

This has got to be the dumbest question I've ever heard.

If you HAVE to get a tattoo, shouldn't you like something a lot and THEN decide to get it tattoos permanently on your skin?


--

Why not "E=MC'" squared"?

[Sean Johnson]

I mean really; just because it is semi-archaic and everybody knows it, It is nevertheless very important. When one regards the history of where our current notions of reality exist, this particular equation permeates the very infrastructure of societal norms itself. Why not have a tattoo of this mind provoking equation? This equation is so basic that it begs for more elaboration and complexity. I say it's the perfect equation for a tattoo.

Re:Why not "E=MC'" squared"?

[Sean Johnson]

Oops! Obviously I didn't see that. My goof!

ok computer.

[nsane]

1=2 we hope that you choke.

Re:ok computer.

[anacron]

Apparantly not a lot of /. fans are Radiohead fans.

.anacron

a pretty proof

[Anonymous Coward]

How about one of the wordless proofs of the Pythagorean Theorem?

Well....

[Fencepost]

I may come off sounding like a conservative old fart, but if this is her first tat and she doesn't already have something personally meaningful that she wants to use then perhaps she should reconsider getting (semi-)permanently inked.

Of course if she already has other tats and wants to add a formula as another but doesn't have anything particularly meaningful to her in mind, I think it'd be hard to beat Grey's suggestion or something patterned after it. Failing that, there are all sorts of interesting things to use from the simple, compact fundamentals to larger "unexpected" items. Ask one of the math faculty or a calculus student about curves where the area under the curve is infinite but the volume of the solid created by spinning it is finite.

If nothing else, she should keep in mind that she's likely to be asked semi-regularly what it means, and if she can't explain it she's going to end up feeling stupid. "Hey, what's the math tat mean?" "Um, I can't really explain it, I just thought it looked neat..."

-- fencepost

The answer, my friend, is in the Quadratic

[Controlio]

The coolest looking formula, due to it's many cool symbols and two-tiered layout, is the Quadratic Formula. I can't even come close to typing it out here, but written down it looks pretty badass.

In words, it is as follows:

X equals negative B plus or minus the square root of (B squared minus 4 times A times C) all over 2 times A

Plus, it's a very widely recognized formula, so you have that going for you also.

Re:The answer, my friend, is in the Quadratic

[LuserOnFire]

I totally agree with you. When I read the question of what tattoo to get, this was what came into my mind.

It looks cool, it's somewhat recognized....plus it has the bonus of being the only formula I can explain what it's used for and how to solve it ;)

An old favorite

[Anonymous Coward]

((ru)/18)qt(pi)

Fibo

[SlamboS]

You could also use the formula for generating the nth number in the fibonacci sequence. It's on the internet... if you want it just do a search. It's pretty interesting.
/whois John Galt

Re:Fibo

[galore]

this is binet's formula. it's wonderfully interesting, and worthy of the aforementioned cause.

http://cut-the-knot.com/arithmetic/Fibonacci.htm l

the dot product!

[incast]

a b = |a||b|cos(t)

(t should be a theta)

Favorite Formula

[annielaurie]

I'm going to post mine before I go look at everybody else's:

1.618

Annie

Re:Maxwell's Equations

[hgc]

I have to agree. Maxwell's equations in point form are the most beautiful mathematical expressions I have ever seen. See here for an example.
-- hgc

Hello World!

[Tec]

Sure, it's not a formula, but it's something every programmer in the world is going to be familar with.

That's why I got it tattooed on my back in binary. *grin*.

All uppercase characters, ASCII encoded (I figured most people aren't fluent in EBCDIC.)

-tec

Cheap digital camera pic of it here.

------------------

Re:Maxwell's Equations

[esonik]

Better write them down in covariant form - even shorter and more elegant, and more geeky (will not be recognized by EE students however).

Symmetric

[segher]

I always found

\Int_0^\inf x^{-x) dx = \Sum_{n=1}^\inf n^{-n}

to be very beautiful.

The best formula

[HeLp2001]

(TM) = a small n X(TM) + Y(TM) = Z(TM) This is a impossible theorum and was thought up in 1630 and was solved in 1995. It has no answer as an integer because n is less than or equal to 3.

ouch!!

[angry old man]

OUCH!!

DeCSS

[bluestar]

How 'bout one of the 7-line DeCSS implementations?

Circumvent this!

Euler

[trexl]

I have to concur with the first gentleman that suggested Euler's formula.Euler himself said that it was proof of the existence of god/ a god. So not only is it mathematical, it's spiritual, and in some odd way tribal.

My vote

[AstroJetson]

Well, as others have pointed out, you can't beat the sheer elegance of Euler's Formula. But if her pain threshold is pretty high another worthy candidate would be...

In the beginning God said:

[insert Maxwell's equations]

...and there was light.

Maybe...

[dcollins]

e^(i Pi) + 1 = 0

Re:Maxwell's Equations

[joib]

Yeah, quantum field theory is full of interresting equations and operators. Turns out you can develop most of quantum mechanics from the commutation relations of the creation and annihilation operators and some group theory. So these would be an obvious choice. But seriously, this is _very_ difficult stuff. Do you really want to lecture a course in QFD to that jerk on the beach with a mental capacity barely exceeding the ability to sell burgers at Burger King? Personaly, I would think twice about the idea to tattoo any formula. It stinks of some kind of "I'm smarter than you" attitude. It's the kind of attitude that alienates the intellectual people from the "normal" people out there. The first reaction when seeing a formula as a tattoo might very well be: "What a loser. Get a life!".

If you're into karate...

[sjbe]

The equations for Force (F=MA), Momentum (P=MV) or Kinetic Energy (KE=(1/2)MV^2) would be appropriate. (geeky but appropriate)

Re:If you're into karate...

[ASCIIMan]

Wouldn't equations dealing with impulse be more appropriate for a matial arts relation?

Re:Maxwell's Equations

[Anonymous Coward]

Hey, remember, it's about a girl! So, according to your theory, it would keep away the lame guys (which is good) and maybe attract the smart guys (which again is good).

pie?

[terpia]

How about just calculating pi out to a hundred places and have the tattoo spiral outward from 3? Either that or a block of Seti data....

No! No! No!

[Anonymous Coward]

If she's gonna be that dumb....

She should get the RSA code tattooed on her ass. Then she's classified as munitions.

Gives a whole new meaning to blonde bombshell.

Schematics

[__aaahtg7394]

I keep meaning to go and get a 2bit-with-carry adder schematic tattooed on my chest. Using the ANSI logic symbols, of course.

Anybody have favorite schematics they'd get tattooed?

Re:Schematics

[Schwarzchild]

How about a Op-Amp with a feedback loop?

Beer's Law Is An Obvious Choice For A Drunken Tat

[SloppyElvis]

Get really sloppy, and Beer's Law will be the only choice...

A = (absorptivity)bc

get the Decss!

[isotope23]

get the code then watch RIAA sue you for your body art!!!

Re:Maxwell's Equations

[MarkPinTx]

I went to UT (thats Texas) (at Austin). The physics kids put together a tshirt that read on the front: And on the seventh day, the Lord said, let there be and on the back: Maxwell's equations. I thought that was chucklicious.

Limit function

[MarkPinTx]

Another good one possibly, the engineering students (us) put together a tshirt as a limit function: the limit, as GPA approaches 0, of engineering = Business Best done in the sigma form methinks Could do the same for Microsoft Limit as IQ approaches 0 is MS or something

Huh?

[schon]

If that's supposed to be binary, shouldn't that be
"1 + 1 = 10" ?

Re:Huh?

[math nazi]

Obviously it's not binary. It looks like cuneiform.

Re:Huh?

[GTRacer]

No, no, no...

It's a $ concatenation!

GTRacer
- Will work for GT3

Re:How about a proof?

[ASCIIMan]

Division by zero error. Process Terminated.

Re:Tattoo

[Anonymous Coward]

Because then people would keep linking to her.

wouldnt it be easier...

[holzp]

wouldnt it be easier to just tattoo, "please kick my ass, and ladies, stay away."

How about the RSA equations?

[archnerd]

How about the equations necessary for RSA encryption/decryption? Fermat's little theorem, Euler's law, etcetera. Wouldn't it be fun to have the government place export restrictions on you?

I'm getting a circuit board

[fishexe]

whenever I get around to it
not a suggestion, just what that made me think of


Ever get the impression that your life would make a good sitcom?
Ever follow this to its logical conclusion: that your life is a sitcom?

I suggest...

[Vintermann]

...That you tattoo your public key. As an image, if it's big. And if QC's are invented, you can just tattoo "REVOKED" over it. That would look cool too, plus it would say: "I was in on this from the very beginning you know"

Fantasy Island

[Eponymous Mallard]

Tattoo says:

x/a + y/b + z/c = 1

"The plane! The plane!"

The Eponymous Mallard

3.14159265358979323846264338327950288419716939...

[Derring]

I have Pi tatooed on me.
It's accurate to up to 214 decimal places.
Unless it's real cold outside, then it just gets rounded to 3.

DeCSS. Drake Equation

[Pseudonymus Bosch]

What about DeCSS code?

And there's the Drake Equation about the number of extraterrestrial civilizations. Quite transcendental, if not mathematical:
N = R* × fp × ne × fl × fi × fc × L

__

only one equation?

[nijso]

One equation is not enough to pass even the simplest test. If you really want to make it in life, you should at least tattoo an entire book on your chest - and carry a mirror with you at all times. Preferably, you should tattoo your entire body to make optimal use of "body language". If you have enough room for a magnifying glass, you could tattoo about 1000 pages of text and equations on your body. I suggest "Partial Differential Equations" by W.A. Strauss, 425 p. and "Viscous Fluid Flow" by F.M. White, 614 pages; These books should put you firmly on the road to the meaning of life.

How about...

[V_M_Smith]

2+2=5
At least that's what Big Brother told me...

Possible solution

[biohazard99]

My high school calc teacher made us devise a mathmatical name/expresion for ourselves that became the bonus questions on exams when evaluated with her criteria, it made for some interesting examples especially a girl in there that was named Xelpha

Re:Maxwell's Equations

[biohazard99]

No need to explain, nearest net access to Knoxville TN is at Oak Ridge.

Do any Math Geeks have an opinion?

[Schwarzchild]

on who is the greatest mathematician ever?

I've often heard of Gauss being it but I've always admired Euler more than Gauss. Euler may have published more mathematics than anyone else as I read in a math textbook once plus he was rumored to have incredible mental calculating ability which would of course have come in handy since he lost sight in one and then the other eye as he grew older.

Re:Axioms "obviously" true

[DickBreath]

What happens when obviously true axioms turn out not to be true?

I'm not an expert, so I hope not to insert foot into mouth. (Although certian other body parts are fine.)

For example. An obviously true axiom: two lines which are parallel to each other can be extended infinitely in either direction, and the two lines will never meet. Problem however. If our universe is the three-dimensional "surface" of a four dimensional sphere, then the parallel lines will meet -- twice -- at each point, halfway around the universe, until each line goes all the way "around" the universe back to it's starting point. Just like Mr. A Square's universe might seem 2D, it might really be the 2D "surface" of a 3D sphere. If Mr. A Square extneds a line far enough, it eventually meets it's starting point. Our line is curved in the fourth dimension all the way "around" the universe, just like Mr. A Square's line is curved in the third dimension, which he cannot percieve.

Mobius Strip

[sylentprofet]

well, though not a formula, a Mobius Strip (too lazy to add accent marks and such) would be a pretty neat representation to have inked onto your person. that or a Klien Bottle (methinks that's the spelling). one sided objects and topology all together is pretty interesting. for a pretty interesting pitch on the Mobius strip, read Necroscope by Brian Lumley. good times....

Re:Axioms "obviously" true

[Schwarzchild]

Axioms must be specified with regard to a particular geometry.

Geometries

Euclidean-->Spherical-->Hyperbolic

One of the basic axioms of Euclidean geometry is that a point not on a line contains a line parallel to the line. This kind of sounds like what you meant to say in terms of axioms.

It is true that "world lines" in Spherical geometry are "parallel" to each other and perhaps that is what you are really referring to? IIRC parallel lines in this geometry are indeed parallel since the end points are at +/- Infinity. The lines technically do not ever meet.

wave-state equation

[StandardDeviant]

findable in any physical chemistry text (usually in the first chapter (maybe second) dealing with quantum). The nice thing about it is that it would be "tunable" for the subject's pain threshold, and it has cool greek letters in it (I say tunable because the form of the Hamiltonian operator depends on what dimensionality system yer lookin' at (hint: if they like to pour hot wax on themselves for kicks give them the 3d polar coordinates version, which expands quite a bit with that lambda thingy (the Lambertian? something like that, I can never recall the name) that ends up in the Hamiltonian).

But make sure they understand what the equation means, like a previous poster said. Covering yourself with Greek gibberish is just as bad as the fools that had the Hip'n'Trendy(TM) Kanji tats done when they don't speak Japanese. I've thought about getting my fav russian quote done, but that's only becuase I'd know if the tattoo artist decided to write "I am a stupid American" rather than "pravda harasho, a chaste luche[1]", which is not idle speculation as a local shop had/has a big flashy kanji tat offering that translates as "I have no fucking clue what this means becuase I'm an idiot." according to my Japanese-speaking friends.

[1] "The truth is good, but happiness is better.", and what I wrote up there is of course just a mangling of english letters to sort of produce the same sounds as the cyrillic/russian words.

--
News for geeks in Austin: www.geekaustin.org

Union of M with m

[Bazman]

I've seen lots of people with this tattoed on them
Its the union of the set M with the set m. It looks like this:

M u m

I can't think why it's so popular.

Baz

How about 42?

[MadCow42]

With the typical Slashdot community, I'm surprised nobody's suggested she tattoo the number "42".

As any self-respecting geek would know, 42 is "The answer to Life, The Universe, and Everything!".

MadCow42.

Re:Axioms "obviously" true

[dillon_rinker]

One of the joys of mathematics is proving the consistency of a set of axioms. In other words, start with a set of statements and prove that none of them can be disproved by using the other axioms. If one of them can be, then you have to throw some axioms out.

In short, given a consistent set of axioms, NONE of them are false. They can't be. If any of them were, then the axioms are not consistent, and that flies in the face of what I told you in the first sentence of the paragraph, doesn't it?

HOWEVER (and this, perhaps, addresses your concerns), when you try to apply mathematics to reality (as you do by asking if lines REALLY ARE PARALLEL) you don't have mathematics anymore; you have physics. You can have a beautiful, consistent set of axioms that describe no reality that ever existed.

BTW, note that, in reality, points and lines don't exist - or at least, they've never been observed. I've seen graphite deposited on paper, I've seen glowing phosphors on a piece of glass, I've seen calcium carbonate dust on slate. But I've never seen a point or a line. Therefore, all of geometry is false. :)

So will you tell us what happens?

[DiSKiLLeR]

So will you tell us which Mathematical formula she does get tattoed?

More importantly, will we see pictures?

D.

I have this formula tattoo�ed on my lower arm.

[Bovspryd]

The Poisson-Jensen formula is one of the greatest formulas in komplex math. And since both I am danish and Jensen where danish it thought it would be a nice tattoo... The formula can be found with this link. http://www.uv.es/~anamat/practicas/prateofun.pdf Page 11. Ejercicio 3,26, d... I can inclose a pix if anyone wanna se it.

an equation and a punchline

[DeltaStorm]

A usefull tatoo would be
pi*r^2
which is of course pie are square, but everyone knows they're round