xkcd- The explanations

Cafe Society
1

So like most dopers I love me some xkcd, but unlike most dopers, there are just some of them that I just don’t get.

So I’m gonna link to the ones that I don’t understand, and see if anyone can explain them to me:

Kepler- Isn’t he an astronomer?

Fourier- Really don’t even know where to start

Schrodinger- OK, part of me knows this only because they explained it on the “Big Bang Theory”. Isn’t it like you don’t know what an outcome will be unless you have actually gone through the steps to get it? Am I close?

Rieman-Zieta- If anyone wants to skip this, go ahead. It looks REALLY complicated…

Computational Linguists- I don’t even know what a computational linguist is…

Blogofractal- This seems like another one that might be too complicated to explain, but I’ll put it here regardless

Pointers- Computer stuff…not my forte

Sandwich- The comic that started it all! This one is the actual reason why I thought “ya know, I’m gonna make a big-ass thread and ask about the comics I don’t get.”

Commented- This one might not even HAVE a meaning, but I’ll include it.

E to the pi times I Math. Not a clue.

Nash- Don’t know the name at the end, an author?

Right-Hand Rule- Totally lost on this one. Totally

What xkcd means- This is mostly the third panel.

Regarding Mousollini- I don’t know what Godwins Law is…

Wikipedian Protester- Oh I understand this, I just think this is pretty much the symbol of the SDMB

Ya know…there are probably more…but I have been at this for like, 2 hours, and frankly I am tired…so that is the list for now, any help with explanations are greatly appreciated.

2

One of Kepler’s laws is that an elliptical orbit will sweep out the same area in a given amount of time, regardless of the orbit or the position thereon.

That was the only one I had the energy to look at.

3

I know the tiniest little bit about that. Basically, in MRIs, the machine takes signals from hydrogen protons. These signals are then transformed into an image using the Fourier transformation. Don’t know any of the physics behind the actual formula though.
Here’s an explanation in howstuffworks.

4

Sudo is a Unix command used to allow the user emulate the user settings of someone else.

Godwin’s Law states that the first person to compare something to Hitler/the Nazis automatically loses the debate argument.

5

“Now you’re just fucking with me” is more or less equivalent to what one Doper said in post #19 of this thread:

(Chronos gave an explanation a few posts later.)

6

In programming if you want to write a comment in your script you write it next to a // and it shows up in green.

7

The Riemann Zeta function* is the subject of arguably the greatest unsolved problem in mathematics: the Riemann Hypothesis, and it relates to the distribution of prime numbers.

If anyone’s really interested in learning more, I can recommend the book Prime Obsession by John Derbyshire, but it still won’t make the comic any funnier.

*The hyphen really shouldn’t be there. It’s Riemann’s Zeta Function, Riemann being the mathematician who famously studied it, and zeta being the Greek letter he used to denote it.

8

It was kind of funny.

9

One of the common, sarcastic ways of referring to the online communities of blogs is the ‘blogosphere’. I think he was just taking that in a random, funny direction.

The right-hand rule is used in physics–basically, when you want to measure…something…the math works in multiple directions…I think…and you have to remember which way the answer is supposed to point. The right-hand rule helps with that…

I don’t remember much from physics class.

10

Whilst compiling this list I made every effort I could to avoid posting the computer things that I didn’t get. I knew that if I tried including those I would have linked to damn near 3/4 of the site, and that I wouldn’t have understood it no matter how many people explained it to me. Apparently some computer stuff got through, but so far awesome info everyone…if there are more explanations out there I’d love to hear em.

Also if anyone else wants to contribute to the list with stuff they don’t get…go right ahead.

11

“Big Bang Theory”? “BIG BANG THEORY”? You aren’t a real doper.

I assume you get the “A Beautiful Mind” reference? Richard Feynman was the rock star of the physics world, known for inventing the Feynman diagram, explaining complex physics so that even undergrads can grok it, playing the bongos, lock picking, and writing an amusing memoir in which he spends a chapter explaining his discovery that if you ask a girl up front if she’ll sleep with you as a condition of the date you’ll get laid a lot more and waste less time taking cold fish to the movies. He was and is much beloved by his fans. He’s probably the only physicist in history (except maybe Einstein) to HAVE fans. Ask any science geek to name their top three personal heroes and he’ll be on the list at least twice.

12

The guy referred to in the third panel is Richard Feynman. Feynman was a Nobel Prize winning quantum physicist. He was also an enormously charming raconteur, and if any physicist would have been able to pick up three girls at a party at once, it would have been him.

Dr. Nash is John Nash, the subject of the movie “Beautiful Mind”, and game theorist. He came up with what’s known as the Nash Equilibrium. That’s a situation where each member of a group makes the choice that will benefit them the most, given the choices of all other members of the group. Therefore, in a Nash equilibrium, no one has an incentive to unilaterally make a new choice, even if every member of the group can benefit if everyone makes different choices.

13

It wasn’t Catherines ZETA-Jones’ grandpa? Damn!

14

Ok, much to the chagrin of Alan Smithee I seriously do not understand Schrodingers Cat.

I don’t get Cecil’s explanation because it is in a poem, and every other explanation I get it WAY too technical and smart for me.

I am not a smart person. Could somebody please explain this to me in terms even I could understand?

15

Schrodinger’s cat is a thought experiment from quantum physics involving a cat and a vial of poison in a box. The basic idea is that until you measure certain types of quantities, they can be considered to have any possible value; i.e. the cat is simultaneously alive and dead until you open the box and look.

This one just makes a fractal (an shape where each part is a miniature version of the same shape) out of a bunch of blogs. The “joke” here is really just looking at the shape and how the author makes fun of various famous blogs (e.g. Corey Doctorow is a little upset about copyright law – isn’t he always?! Har har.)

A pointer is a variable in a computer program which holds a memory address. (It “points” somewhere else in memory.) So in response for a request for “pointers,” the other character rattles off random memory addresses. The “0x” prefix indicates they are in hexadecimal (base-16) notation, which is the standard way to look at those things. The only joke here is the two definitions of “pointer” – there’s nothing significant about the addresses themselves.

On Unix-type operating systems, sudo (superuser-do, pronounced pseudo) is a command that lets a regular user execute certain commands with root (superuser) permissions. The joke here is that frequently a user will attempt to run some command, realize they don’t have the permissions, and then sudo it and it works.

The only joke here is that e[sup]pi * i[/sup] = -1 is really freaky. I mean, you’ve got two transcendental constants and an imaginary number, stick them together, and you get -1? WTF!

Richard Feynman is a famous physicist/mathematician and reputed ladies’ man. John Nash is a famous mathematician who really did develop some game theory stuff inspired by picking up chicks. The joke here is that Feynman has ruined his plan by simply picking up all the chicks.

Godwin’s Law: as a discussion goes on, the probability that someone will compare you to Nazis or Hitler approaches 1.

16

It’s probability, basically.

Take away the cat in a box and think about a coin flip instead. Flip the coin, and slap it down on the back of your hand. You don’t know what the outcome is, right? There’s a 50% chance it’s heads and a 50% chance it’s tails. Schroedinger’s claim is that until the coin is observed, it exists as both heads and tails simultaneously, because there’s an equal probability of each. It’s not until you take your hand away that the coin resolves into being heads face up.

It goes deeper than that, since it’s not just a general theory about probability and has to do with more advanced theoretical science, but that’s the general gist of it. Until you observe the outcome, the object in question is both things at once: heads and tails, alive and dead (in the case of the cat).

17

In some computer languages, there is a construct called a pointer. It is a raw address to some chunk of memory and usually written in hexadecimal (as it is in this comic).

ETA: late as usual so here is a pointer to more info.

18

It goes deeper than that, btw, because it appears to be how subatomic particles really work. They seem to exist as waveforms until they’re observed, at which point they become distinct particles.

19

Right. There’s a reason it’s Schroedinger’s Cat and not Schroedinger’s Coin. :slight_smile:

20

A little more detail on Schroedinger: You know how in quantum mechanics light (and everything else, in fact, but most noticeably light) sometimes seems like a wave and sometimes a particle, right? And how we can know where an electron is or how it is moving but not both (Heisenberg’s Uncertainty Principle)? QM is full of this sort of thing and according to the most common understanding, any attempt to get at the “real” answer is doomed because the real answer is that light is both a wave and a particle, and the electron really doesn’t have an exact location and an exact speed at the same time - these things only resolve when someone observes them, and the particle is over here or over there, but the rest of the time there literally is no answer to how things really are. Things at a quantum level exist in a state of probability, not this or that but 50% this and 50% that.

With me so far?

Einstein objected that this isn’t possible, that it might seem to make sense when you’re looking at equations, but that the real world couldn’t work that way. Schroedinger countered that the real world works exactly that way, and to show that he meant it he developed a thought experiment. What if one of these statistical probabilities had real-life consequences. Say you built a trigger that would release poison gas if the particle is here but not there. And then you locked a cat inside a box with the device and a piece of radioactive material that has a 50% chance of producing a particle here, such that the poison is released. Einstein (and most people) would say that the particle is either in the right place to set off the trigger or it isn’t, and so the cat is either alive or dead, one or the other. But Schroedinger said No! The particle hasn’t been observed yet (because the box is still locked) so the particle, the trigger, the poison, and the cat all exist in a state of quantum indeterminacy: 50% here and 50% there, 50% dead and 50% alive. Only when you open the box and look at the cat, can you say that the particle did or didn’t get produced. Until then it is just a probability with no actual answer one way or the other. In other words, Schroedinger called Einstein’s bluff: even when you’re dealing with a real-life situation with a real live (or not) cat, the universe does work that way and you can’t prove otherwise! And sure enough, Einstein and others tried and tried to prove that there is some way of showing that the cat either is or is not alive before you look in the box, but not only could they not prove Schroedinger was wrong, but any other way of looking at things meant that even stranger things had to be true (which also couldn’t be proved or disproved). Eventually most quantum physicists gave up and admitted that Schroedinger was right: that saying that the cat is both alive and dead at the same time makes at least as much sense as anything else they could say, and it fits with the equations. Every now and then I read about scientists still trying to come up with an experiment that would prove whether or not the universe really works like this or not (the high IQ version of proving the light stays on when you close the fridge door), but so far they haven’t gotten anywhere as far as I know.