XKCD cartoon: Equations

Unfortunately I’m not educated enough to get any of the jokes except for the chemistry equation. Will someone break it down for me?

You may find this (and the rest of the site) helpful:


When I saw this I thought of a recent thread where somebody asked about an equation and the answer was more or less it’s a ??? equation. I can’t remember the category that was given. Maybe heat or fluid.

I tried Googling for the thread and can’t find it. Google has been failing me on finding threads here recently.

Anyone? Ferris?

You mean this? https://boards.straightdope.com/sdmb/showthread.php?t=696794

Mostly physics there.

There have been a number of occasions when I didn’t get the punchline in an xkcd strip. But this time, I figured I wouldn’t even understand the explanation of the punchline.

Nope. I found that one in my search. The one I remember was a question about one on a t-shirt. And it was a single equation like a heat flow one or some such.

The chemistry equation is funny, treating HEAT like a actual compound.

If I take the time to understand the others (yes, I’m willing to spend a semester studying Gauge Theory and Fluid Dynamics) will they be funny, too?

Was it any of these?

30 + 30 = 39. Please Explain

What’s Your Perspective on the Image on This Shirt?

Maxwell’s Equations on a t-shirt: summing up light

Looking for science/mathematics shirts!!

Lift formula

Identify the equation on this t-shirt?

It’s possible to explain the joke without explaining the equations themselves. In broad terms, the equations of certain areas of science tend to have certain mathematical features. One who’s at least passingly familiar with those fields can look at such an equation and say, at a glance, “That looks like a relativity equation”, or “that looks like a stat mech equation”, or the like. One might or might not, depending on familiarity with the field in question, be able to take a closer look and say “Oh, yes, that’s the Schwartz-Bupkus Equation”, or the like, but you’ll usually be able to recognize at least the general field.

None of the equations in this comic are correct, and most of them don’t even make any sense. But they all look right for equations of the appropriate field. Which is probably a sign of expertise: Anyone can grab a random textbook off of the shelf and pick out some real equation out of it, but it’s tough to come up with a fake equation that looks real.

True. But being fake isn’t a joke.

CH[sub]2[/sub] + O[sub]4[/sub]N -> CHO[sub]2[/sub] + HN + O[sub]2[/sub] looks like a chemical equation even though its complete nonsense. But it doesn’t have a punchline.

By adding HEAT the way he did, Munroe made a fake chemical equation that was funny.

I’m assuming he did the same with the other equations. That they’re not just convincing fakes but that they also contain some detail that is humorous. So that people who understand the science involved can see the fake equation and say something like “Did you see that? He used έ as a divisor instead of a multiplier. That’s hilarious.”


The supposed ‘quantum gravity’-equation doesn’t fit, though: you’d expect to see things like that as the symmetry group of some gauge theory (such as the Standard Model’s SU(3)xSU(2)xU(1)), so this would perhaps better fit the label ‘all grand unified theory equations’. Of course, as written, it’s just nonsense.

I appreciate the effort, but to be clear this was from a thread just a few months ago.

It’s this one.

That’s it!!! Thank you.

Yeah, comparing the equation on that t-shirt with the fluid dynamics one in the strip shows they are quite different. So Randall missed this one. After all, as watchwolf49 said: “It looks complicated, must be Navier-Stokes …”

(Note: I searched Google/this board for “equation” and “fluid dynamics” for the past year and that thread did not turn up.)

I am impressed that Munroe has that expertise in all those fields. Actually I’m impressed that **Chronos **knows that all the equations are wrong. I don’t even know what gauge theory is.

This comic is like the math version of the joke, “Everything in French sounds like lovemaking, everything in Italian sounds like a fight, and everything in German sounds like a command.”

My gauge theory is “If the needle never moves, or if the needle swings around wildly, the gauge is probably broken.” :slight_smile:

Mine is: “a tool or part will always be exactly one size too large or too small”.

That’s because you’re a reasonably good guesser. When I choose a tool or part, it might be exactly right, or nine sizes too large or small - you never know. :slight_smile: