0356: "Nerd Sniping"

[Zalde Ocga]

I have friends that read xkcd and since they found this particular one I've seen papers that have confusing problems on them... I think I'm being conspired against...

[mclemme]

Made a nerd sniping ripoff for my hobby webcomic when I was bored the other night:
http://brajn.org/comic/qr-code-sniping

Thanks for the inspiration!

[addams]

I got nerd sniped.
I want to tell the story.

I was a Yucca Mountain Information Center with a friend.
http://en.wikipedia.org/wiki/Yucca_Moun ... repository

There is a great deal of information there. I was reading what I could. My friend was reading the math. It was hard for him. Some of it took him a while. Most of it was so far over my head that I did not need to duck.

Then, it happened. We walked around a corner together. There it was. A pedestal with a bowl on top. One nice bowl that was placed so that the labels could be read by a person that walks around that corner.

SPENT NUCLEAR FUEL ROD

We both stopped, dead in our tracks. There were some seconds that went by. Twenty seconds. "We are dead." Was said.
I don't know who said it. It could have been either one of us.

I moved first. I knew if that shit was real, then, we were dead. I wanted to look at it.

I walked over to the bowl, picked one up and said, "It's light."

He said, "It's light?"

"Yep.'' I lifted it to show him.

He ran over to that bowl. It was so funny.
I wonder; Do they have a camera on that bowl? How long different people stay frozen would be interesting.
The audio would be fun too. "Look Ma! They are giving away Fuel Rods!"

Do people ever read the label and run away? That is funny. Do they think that they have been exposed?

What I do know is they 'GOT' us. We were two Nerds that were down.

It was, just, too fucking interesting for about twenty seconds or so.

I know that this post may ruin the fun for those guys. The number of people that will go to Yucca Mountain, that also read this comic? That overlap may be quite high. Hey! If, the guys that did that practical joke read this comic, then; You Got Us!

We laughed a lot. That was one of the funniest things we saw on that Road Trip. We saw a great many funny things. That bowl of spent nuclear fuel rods was the funniest.

We talked about tourists as a fix for the fuel rod problem. It gave us something to think about for a while. Human nature being what it is. It might work.

[webgrunt]

I got nerd sniped.
I want to tell the story.

I was a Yucca Mountain Information Center with a friend.
http://en.wikipedia.org/wiki/Yucca_Moun ... repository

There is a great deal of information there. I was reading what I could. My friend was reading the math. It was hard for him. Some of it took him a while. Most of it was so far over my head that I did not need to duck.

Then, it happened. We walked around a corner together. There it was. A pedestal with a bowl on top. One nice bowl that was placed so that the labels could be read by a person that walks around that corner.

SPENT NUCLEAR FUEL ROD

We both stopped, dead in our tracks. There were some seconds that went by. Twenty seconds. "We are dead." Was said.
I don't know who said it. It could have been either one of us.

I moved first. I knew if that shit was real, then, we were dead. I wanted to look at it.

I walked over to the bowl, picked one up and said, "It's light."

He said, "It's light?"

"Yep.'' I lifted it to show him.

Excellent!

I've got a bucking bar made of 95% tungsten, 5% nickel. It's a section of rod about 2 to 2.5 inches in diameter and about the same length. I have no use for a bucking bar, I got it to show people because it's so unexpectedly dense it's fun to handle. I'd prefer iridium or even platinum, but I can't afford five pounds of either of those substances.

It's clearly a section of a rod, though. I wonder if I could get anyone to believe it's part of a spent nuclear fuel rod. I suppose it might help if I warm it up to around 120 F first, just for effect. "I lucked out, it's not quite fully spent!"

[addams]

I got nerd sniped.
I want to tell the story.

I was a Yucca Mountain Information Center with a friend.
http://en.wikipedia.org/wiki/Yucca_Moun ... repository

There is a great deal of information there. I was reading what I could. My friend was reading the math. It was hard for him. Some of it took him a while. Most of it was so far over my head that I did not need to duck.

Then, it happened. We walked around a corner together. There it was. A pedestal with a bowl on top. One nice bowl that was placed so that the labels could be read by a person that walks around that corner.

SPENT NUCLEAR FUEL ROD

We both stopped, dead in our tracks. There were some seconds that went by. Twenty seconds. "We are dead." Was said.
I don't know who said it. It could have been either one of us.

I moved first. I knew if that shit was real, then, we were dead. I wanted to look at it.

I walked over to the bowl, picked one up and said, "It's light."

He said, "It's light?"

"Yep.'' I lifted it to show him.

Excellent!

I've got a bucking bar made of 95% tungsten, 5% nickel. It's a section of rod about 2 to 2.5 inches in diameter and about the same length. I have no use for a bucking bar, I got it to show people because it's so unexpectedly dense it's fun to handle. I'd prefer iridium or even platinum, but I can't afford five pounds of either of those substances.

It's clearly a section of a rod, though. I wonder if I could get anyone to believe it's part of a spent nuclear fuel rod. I suppose it might help if I warm it up to around 120 F first, just for effect. "I lucked out, it's not quite fully spent!"

What fun! I would like to see your bucking bar. I like that sort of thing.
Yes. For persons that know about the heat then warming it up would help the practical joke. It makes a great practical joke.
When I was a young person, humans were still working on what radioactive materials were. There was Uranium being mined in Eastern California. I held some. I did not hold it long. There were adults teasing me.
I was asked what I thought it was. I said, "It is a rock that has been in the sun." The men laughed at me. The rock felt like a rock that has been in the sun. It really is warm to the touch.
I would love to help you with your practical joke. You have a small problem. If, the audience knows nothing about nuclear physics, then, the joke will fail. You may need to educate your audience a little. Tell a friend or co worker that has never seen your bar that you must study physics. Show them some facts. Wiki is good for that kind of thing.
Then, What? Once your audience knows a little something. Then, What?
Gee Willikers. You could tease the security people at the local airport. They might take your bar. Don't bother if you are in Canada.

I had a flute in a pcv pipe. It looked like it could be a makeshift bomb. The Americans were on me when I walked into the ticket counter. In Canada no one gave me or my pipe bomb a second look.

How could you go Nerd Sniping with your very heavy bar? There has 'got' to be a way. It would have to be warm, if, you want to 'get' people in physics departments. Who could you 'get'?

Your spouse would be my first guess. But, your spouse has already seen you bar. Both of them. So, you need someone else.

That year that I knew the Chemist, I got 'got' several times. He was fun. Of course, a bunch of it was scary. He would 'get' me with a scary fact. Then, I would 'get' him with a natural wonder. He was running out of scary facts. I still had natural wonders to spare.

[levantis]

Ok, this is waaay old, but still, just for those who wish to experiment and don`t have a master`s education:
the answer for a 49-element grid is 0.774 382 +- 0.000 047. And here`s the code:

Spoiler:

Clear[smallRectEq, meshEq, eq, sreqs, meqs, eqsys, potential, \
potentials, solution, currents]

smallRectEq[x_, y_] :=

i[x, y, x + 1, y] + i[x + 1, y, x + 1, y + 1] - i[x, y, x, y + 1] -
i[x, y + 1, x + 1, y + 1] == 0

meshEq[x_, y_, size_, source_] :=

If[x > 1, i[x - 1, y, x, y], 0] + If[y > 1, i[x, y - 1, x, y], 0] -
If[x < size, i[x, y, x + 1, y], 0] -
If[y < size, i[x, y, x, y + 1], 0] + source == 0

eq[x1_, y1_, x2_, y2_] := If[And[x1 < x2, y1 <= y2], Sum[
i[x, y1, x + 1, y1]
, {x, x1, x2 - 1}] + Sum[
i[x2, y, x2, y + 1]
, {y, y1, y2 - 1}] == 1
, 1 == 0]

sreqs[size_, x1_, y1_, x2_, y2_] := Flatten[Table[
smallRectEq[x, y],
{x, 1, size - 1},
{y, 1, size - 1}
], 2]

meqs[size_, x1_, y1_, x2_, y2_] := Flatten[Table[
If[
{x, y} == {x1, y1},
meshEq[x, y, size, i],
If[
{x, y} == {x2, y2},
meshEq[x, y, size, -i],
meshEq[x, y, size, 0]
]
],
{x, 1, size}, {y, 1, size}], 2]

eqsys[size_, x1_, y1_, x2_, y2_] := Flatten[Join[
Table[smallRectEq[x, y], {x, 1, size - 1}, {y, 1, size - 1}],
Table[
If[
{x, y} == {x1, y1},
meshEq[x, y, size, i],
If[
{x, y} == {x2, y2},
meshEq[x, y, size, -i],
meshEq[x, y, size, 0]
]
], {x, 1, size}, {y, 1, size}],
{{eq[x1, y1, x2, y2]}}
], 2]

varsys[size_] := Flatten[Join[
Table[i[x, y, x + 1, y], {x, 1, size - 1}, {y, 1, size}],
Table[i[x, y, x, y + 1], {x, 1, size}, {y, 1, size - 1}],
{{i}}
], 2]

currents[size_, x1_, y1_, x2_, y2_] :=
Solve[eqsys[size, x1, y1, x2, y2], varsys[size]][[1]]
potential[x, y] :=
If[y == 1, If[x == 1, 1, potential[x - 1, 1] - i[x - 1, 1, x, 1]],
potential[x, y - 1] - i[x, y - 1, x, y]]
potentials[size_, x1_, y1_, x2_, y2_] :=
Table[potential[x, y], {x, 1, 5}, {y, 1, 5}] /.
currents[size, x1, y1, x2, y2] // MatrixForm
solution[size_, x1_, y1_, x2_, y2_] :=
N[{1/i /. currents[size, x1, y1, x2, y2],
potentials[size, x1, y1, x2, y2]}]

It uses Kirchoff`s equations and some coffee that I drank.

[MichaelKarnerfors]

Once I came accross this total moron... that I in retrospect found was in fact brilliant, because he had turned nerd sniping into a money making venture.

What he did was to say something to the effect of "If you cross a street many times, and you havn't gotten hit by a car so far, the risk that you will get hit by a car increases every time you cross". Basicly he said that independent random events were dependent, and not only that: he posted it on a skeptics' forum.

*BOOM* Headshot...

The nerds went berserk and flooded his blog with comments about what an idiot he was; dozens of explanatory examples showing why independent random events do not magically affect eachother; scans of the standard mathametical statistics textbook for swedish universities (he had quoted that one); a simulation program showing empirically that he was wrong (I did that one); post after post after post... upon which he simply replied "No, you're wrong, I'm right" and just kept holding his position like a textbook Dunning-Kruger victim.

I was about to declare him as living proof that you can survive a dual hemispherectomy... but then I noticed the utter brilliance of his scheme: he had get-paid-for-page-views ads on his blog.

It was genius!! His setup was so simple:

1) Get a blog.
2) Put ads on it.
3) Go nerd sniping (or maybe it's more accurate to call it nerd-baiting / nerd-trolling).
4) Profit!!!

Sheer brilliance.

/Michael

[strokebow]

I was fairly satisfied with my results. So, I plopped in the coordinates for the Knight's move, and ran the test automatically on a variety of number of resistors. A couple results from the middle are as follows:

Spoiler:

4x4 grid (32 resistors): .9955357 ohms
15x15 grid (450 resistors): .7856096 ohms
40x40 grid (3,200 resistors): .7749523 ohms
120x120 grid (28,800 resistors): .7734296 ohms
weighing in at around 514MB memory used, and 66 minutes run time, 320x320 grid (231,200): .7732632 ohms

So, if anyone is interested in a numerical system for solving arbitrary check points and arbitrary sizes for the field of resistors, feel free to check out my code.

http://userpages.umbc.edu/~lohr1/xkcdresistor/

How do you manage to get 32 resistor in a 4 by 4 grid
and 450 resistors in a 15 by 15 grid????

Surely in a 4 by 4 grid you would have 32 resistors???? anyone?

[BlackHatSupport]

I've made myself a sign.

How did the orbital velocity of the moon effect Apollo 13's lauch?

It's simple (ish) but it works quite well. 10 points so far.

[philsov]

is it meta sniping when they correct you that it should be "affected"?

[BlackHatSupport]

is it meta sniping when they correct you that it should be "affected"?

That's half the fun, seeing which ones notice that.

[Yoduh]

I was fairly satisfied with my results. So, I plopped in the coordinates for the Knight's move, and ran the test automatically on a variety of number of resistors. A couple results from the middle are as follows:

Spoiler:

4x4 grid (32 resistors): .9955357 ohms
15x15 grid (450 resistors): .7856096 ohms
40x40 grid (3,200 resistors): .7749523 ohms
120x120 grid (28,800 resistors): .7734296 ohms
weighing in at around 514MB memory used, and 66 minutes run time, 320x320 grid (231,200): .7732632 ohms

So, if anyone is interested in a numerical system for solving arbitrary check points and arbitrary sizes for the field of resistors, feel free to check out my code.

http://userpages.umbc.edu/~lohr1/xkcdresistor/

How do you manage to get 32 resistor in a 4 by 4 grid
and 450 resistors in a 15 by 15 grid????

Surely in a 4 by 4 grid you would have 32 resistors???? anyone?

Don't ask me how he decided it but his math works out if each unit of the grid can each hold sqrt(2) = 1.414 resistors

[UniqueScreenname]

Black Hat Support: I love your signature.

[webgiant]

Once I came accross this total moron... that I in retrospect found was in fact brilliant, because he had turned nerd sniping into a money making venture.

What he did was to say something to the effect of "If you cross a street many times, and you havn't gotten hit by a car so far, the risk that you will get hit by a car increases every time you cross". Basicly he said that independent random events were dependent, and not only that: he posted it on a skeptics' forum.

*BOOM* Headshot...

The nerds went berserk and flooded his blog with comments about what an idiot he was; dozens of explanatory examples showing why independent random events do not magically affect eachother; scans of the standard mathametical statistics textbook for swedish universities (he had quoted that one); a simulation program showing empirically that he was wrong (I did that one); post after post after post... upon which he simply replied "No, you're wrong, I'm right" and just kept holding his position like a textbook Dunning-Kruger victim.

I was about to declare him as living proof that you can survive a dual hemispherectomy... but then I noticed the utter brilliance of his scheme: he had get-paid-for-page-views ads on his blog.

It was genius!! His setup was so simple:

1) Get a blog.
2) Put ads on it.
3) Go nerd sniping (or maybe it's more accurate to call it nerd-baiting / nerd-trolling).
4) Profit!!!

Sheer brilliance.

/Michael

Now, how to do this without actually having to be a seemingly-stupid person.

[forbiddenSpell]

Once I came accross this total moron... that I in retrospect found was in fact brilliant, because he had turned nerd sniping into a money making venture.

What he did was to say something to the effect of "If you cross a street many times, and you havn't gotten hit by a car so far, the risk that you will get hit by a car increases every time you cross". Basicly he said that independent random events were dependent, and not only that: he posted it on a skeptics' forum.

*BOOM* Headshot...

The nerds went berserk and flooded his blog with comments about what an idiot he was; dozens of explanatory examples showing why independent random events do not magically affect eachother; scans of the standard mathametical statistics textbook for swedish universities (he had quoted that one); a simulation program showing empirically that he was wrong (I did that one); post after post after post... upon which he simply replied "No, you're wrong, I'm right" and just kept holding his position like a textbook Dunning-Kruger victim.

I was about to declare him as living proof that you can survive a dual hemispherectomy... but then I noticed the utter brilliance of his scheme: he had get-paid-for-page-views ads on his blog.

It was genius!! His setup was so simple:

1) Get a blog.
2) Put ads on it.
3) Go nerd sniping (or maybe it's more accurate to call it nerd-baiting / nerd-trolling).
4) Profit!!!

Sheer brilliance.

/Michael

Now, how to do this without actually having to be a seemingly-stupid person.

Do the opposite? Post legitimate science on a young-Earth creationist site and link to your blog?

[tomtom2357]

Just to do a bit more nerd sniping here, what is the solution in a 3d grid!

[mrob27]

I only just got around to looking up the answers for xkcd 356, and I noticed that by now some of the links have died.

The geocities page is long gone, of course, but is still on archive.org, at http://web.archive.org/web/200602110027 ... node2.html

From that I was able to find an actual current live version of the same article, at http://sites.google.com/site/resistorgrid/

A better source however (because it has a table giving solutions for many different choices of which two nodes are "marked red" in the problem statement) is the paper by Atkinson and van Steenwijk. A link was given to http://atkinson.fmns.rug.nl/public_html/resist.pdf, which has also gone missing. But Google Scholar turns it up at http://pds4.egloos.com/pds/200708/06/25 ... ariski.pdf

There is a fine line between sniping and trolling. It might have been fun to point out that

\sqrt{\pi}-1=0.772453...

which is only a bit less than

\frac{4}{\pi}-\frac{1}{2}=0.773239...

and ask why it can (or cannot) be one or the other.