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0969: "Delta-P"

Posted: Wed Oct 26, 2011 12:48 pm UTC
by Vrishna
Image

Title text: "If you fire a Portal gun through the door of the wardrobe, space and time knot together, which leads to a frustrated Aslan trying to impart Christian morality to the Space sphere."

This is rare: the new comic not being there when I arrive at the office on 9am Central European (Summer) Time ... Wow, biggest xkcd ever: 4,582 x 9,908 pixels!

Edit: Guess Randall forgot downscaling, and his upload script just took ... err ... a little longer than usual :lol:

Edit 2: Ah, now it's been downscaled to 400x 865 pixels.

Re: 0969: "Delta-P"

Posted: Wed Oct 26, 2011 12:53 pm UTC
by Oflick
I actually thought its size was part of the joke. Then I realised it wasn't.

True story.

Re: 0969: "Delta-P"

Posted: Wed Oct 26, 2011 12:54 pm UTC
by Fenix Rising
In order to see this easily I had to open the main page in Chrome, right click the image and choose "open image in new tab." Also, I had to finagle with the URL to get to the comic in the first place.

As related to the comic, it seems like this approach would make it a bit difficult to target just the witch.

Re: 0969: "Delta-P"

Posted: Wed Oct 26, 2011 12:57 pm UTC
by Monual
Had to copy the image to another tab in my browser to read it.

And lest we forget, the wardrobe is selective about when it opens up. Sometimes it's just a wardrobe.

I hate that the "Chronicles of Narnia" movie series died just before my favorite story in that series, "The Silver Chair". But then, "Voyage of the Dawn Treader" is my second-favorite story and the movie hardly did it justice, so perhaps it's just as well.

Re: 0969: "Delta-P"

Posted: Wed Oct 26, 2011 12:59 pm UTC
by Vrishna
Fenix Rising wrote:In order to see this easily I had to open the main page in Chrome, right click the image and choose "open image in new tab."


For Firefox, right-clicking the image and then chosing the first menu item (must be "Show image" or similar, I'm using the German l10n) works fine.

BTW, "The Wizard of Oz" is not quite as popular in Germany as in the USA, but when we screened it at our university's cinema some years ago, I was surprised that I knew some of the songs/melodies in there.

Re: 0969: "Delta-P"

Posted: Wed Oct 26, 2011 1:00 pm UTC
by Odd_nonposter
Holy giant image Batman!

Fenix Rising wrote:In order to see this easily I had to open the main page in Chrome, right click the image and choose "open image in new tab."


This works, by the way.

Flooding Narnia. Genius.

Re: 0969: "Delta-P"

Posted: Wed Oct 26, 2011 1:00 pm UTC
by TheMegelSmeagol
With the loss of gravity from free-falling and the slowing down of time dues to it being Narnia, it would pretty much be like Inception.

Re: 0969: "Delta-P"

Posted: Wed Oct 26, 2011 1:01 pm UTC
by dp2
Oh, great. Thanks for turning your own comic into a religious flamewar, Randall. Ah, I suppose it's just speeding up the inevitable.

I wonder if it was intentional that it depicts a massive flooding of the land because someone didn't like the inhabitants' idea of morality.

Re: 0969: "Delta-P"

Posted: Wed Oct 26, 2011 1:01 pm UTC
by BrianB
Vrishna wrote:BTW, "The Wizard of Oz" is not quite as popular in Germany as in the USA, but when we screened it at our university's cinema some years ago, I was surprised that I knew some of the songs/melodies in there.


BTW - This is "Chronicles of Narnia", not "Wizard of Oz".

Re: 0969: "Delta-P"

Posted: Wed Oct 26, 2011 1:04 pm UTC
by slivergun
what if the pressure of the water destroy the wardrobe?

Re: 0969: "Delta-P"

Posted: Wed Oct 26, 2011 1:05 pm UTC
by Okita
The mental image of Aslan with the Space Core is hilarious.

"Son of Adam"
"Space Adam?"

Re: 0969: "Delta-P"

Posted: Wed Oct 26, 2011 1:05 pm UTC
by Vrishna
BrianB wrote:BTW - This is "Chronicles of Narnia"


Which is probably slightly more popular here, but nevertheless was completely ignored by me ... Is it worth reading or watching?

Re: 0969: "Delta-P"

Posted: Wed Oct 26, 2011 1:09 pm UTC
by Red Hal
Only if you deprogram yourself by reading Phillip Pullman afterward.

Re: 0969: "Delta-P"

Posted: Wed Oct 26, 2011 1:11 pm UTC
by beggenbe
Vrishna wrote:
BrianB wrote:BTW - This is "Chronicles of Narnia"


Which is probably slightly more popular here, but nevertheless was completely ignored by me ... Is it worth reading or watching?


Yes.

Re: 0969: "Delta-P"

Posted: Wed Oct 26, 2011 1:11 pm UTC
by Fenix Rising
Vrishna wrote:Is it worth reading or watching?


Myself being a Christian, I can say that it was very worth reading. The recent movies also do a decent job. I can see how a non-Christian may not like it due to the Christian nature, but imagine that it is still quite entertaining.

Re: 0969: "Delta-P"

Posted: Wed Oct 26, 2011 1:12 pm UTC
by dexeron
Talk about collateral damage. What about poor Mister Tumnus?!

Re: 0969: "Delta-P"

Posted: Wed Oct 26, 2011 1:14 pm UTC
by MartinKS
I'm usually a big fan of the underlying physics & maths on XKCD, but for some reason the equation in this one struck me as being a little odd...
why does the depth of the ocean factor in the initial flow rate?
Surely the water would start as a trickle and flow in faster as the wardrobe sunk and the water pressure around it increased?

Re: 0969: "Delta-P"

Posted: Wed Oct 26, 2011 1:15 pm UTC
by Firnagzen
Anyone else heard of the DnD campaign where one guy had a ring of transportation thrown into the sea, and the other half of the pair had an adamantium plate with a small hole welded to it?

Re: 0969: "Delta-P"

Posted: Wed Oct 26, 2011 1:17 pm UTC
by edbennion
At the rate indicated in the comic, it would take [imath]1.75 x 10^{15}[/imath] seconds or 55.49 million years to empty just the Pacific Ocean.

Re: 0969: "Delta-P"

Posted: Wed Oct 26, 2011 1:18 pm UTC
by rabidmuskrat
This one took me a minute, but cracked me up when I realized what was going on.

Re: 0969: "Delta-P"

Posted: Wed Oct 26, 2011 1:23 pm UTC
by Number3Pencils
This may be the most efficient way to make two worlds unlivable at one stroke. Narnia becomes an Atlantis, and our world has 2km of ocean drained away.

Unless the Narnians figure out a way to transport their end of the wardrobe into the ocean soon enough, in which case all that happens is that the two oceanic ecosystems get a lot weirder in one small place.

Re: 0969: "Delta-P"

Posted: Wed Oct 26, 2011 1:26 pm UTC
by MuskratNews
Uh, the doors open out.... the inrushing water would close them. Like an airplane door at altitude.

(And I'm not even going to mention that the wardrobe only .... oh, you know.)

Still, clever.

Re: 0969: "Delta-P"

Posted: Wed Oct 26, 2011 1:34 pm UTC
by Eebster the Great
Fenix Rising wrote:
Vrishna wrote:Is it worth reading or watching?


Myself being a Christian, I can say that it was very worth reading. The recent movies also do a decent job. I can see how a non-Christian may not like it due to the Christian nature, but imagine that it is still quite entertaining.

Myself being an atheist, I agree that the books are worth reading, but I do find them a bit overhyped. But they are really great for younger kids (not that adults can't enjoy them too).

It does beat you over the head pretty hard with the Christian morals and themes, though, and I haven't heard anything good at all about the movie.

Re: 0969: "Delta-P"

Posted: Wed Oct 26, 2011 1:36 pm UTC
by FrobozzWizard
Uh, the doors open out.... the inrushing water would close them. Like an airplane door at altitude.


Not necessarily: Depending on how open they are when the wardrobe hits the water, what angle it makes contact, and the strength of various parts, it's quite possible the doors will be ripped off their hinges and float away before the water starts rushing in.

Re: 0969: "Delta-P"

Posted: Wed Oct 26, 2011 1:36 pm UTC
by javahead
MuskratNews wrote:Uh, the doors open out.... the inrushing water would close them. Like an airplane door at altitude.

(And I'm not even going to mention that the wardrobe only .... oh, you know.)

Still, clever.

Well, there is a hole for the anchor, but im sure the pressures would crush open the flood gates.

At first I was flabbergasted by the math, and at this hour that was hard to see what was going on. However, once I managed to see the joke I caught the stares of the entire office watching me laugh.

Yay!

Re: 0969: "Delta-P"

Posted: Wed Oct 26, 2011 1:37 pm UTC
by Grant10k
Number3Pencils wrote:This may be the most efficient way to make two worlds unlivable at one stroke. Narnia becomes an Atlantis, and our world has 2km of ocean drained away.


Problem: Raising ocean levels due to climate change (Or impending Noah-esk flood, depending on how Christian you are).
Problem: White Witch.
Solution: Throw drain into ocean near the level we want our oceans to be. Retrieve drain when ocean reaches acceptable levels.

Re: 0969: "Delta-P"

Posted: Wed Oct 26, 2011 1:40 pm UTC
by Frankie
dp2 wrote:Oh, great. Thanks for turning your own comic into a religious flamewar, Randall. Ah, I suppose it's just speeding up the inevitable.

Already happened last time he made a Narnia comic. Most of us survived it.

Re: 0969: "Delta-P"

Posted: Wed Oct 26, 2011 1:44 pm UTC
by smikey
Vrishna wrote:
BrianB wrote:BTW - This is "Chronicles of Narnia"


Which is probably slightly more popular here, but nevertheless was completely ignored by me ... Is it worth reading or watching?


I'm not a Christian, and I really enjoyed the books as a kid. As an adult, I read them and was much less impressed. I will say this: the Christian allegories are by far the most interesting part of the books. Even not sharing the theology, that's an interesting and creative plotline.

The problem with the books is everything else. Other than Aslan, the only interesting character is probably Reepicheep, and maybe Polly and Digory. The Penvensies are almost uniformly boring, with only brief flashes from Lucy. The plots are simple and underwhelming, and there's really not a lot going on in any of them; they're all really novellas more than full books. The entire series is probably about the size of a middle-range Harry Potter book, and while length isn't everything, it leaves the books feeling rushed and oversimplified.

So in general: well-done symbolism (whether or not you agree with it), some very interesting world-building ideas that don't get enough attention, lousy characters, mediocre plots.

Re: 0969: "Delta-P"

Posted: Wed Oct 26, 2011 1:51 pm UTC
by foilman
The white witch would have plenty of time to avoid the "flood". Time runs much quicker in Narnia so water pouring through from our end in the course of a few seconds would take months to fully arrive there. It would probably result in a small stream.

Re: 0969: "Delta-P"

Posted: Wed Oct 26, 2011 2:30 pm UTC
by BentFranklin
Hydrodynamics humor FTW!

Fun Quiz: Kids, show your skills and estimate how long it would take to empty all the oceans! Remember, as you drain the ocean, d in Randall's equation will decrease. Rename d as h. Then:

dh/dt = -k sqrt(h)

You can assume water transports horizontally instantaneously so the oceans always have the same level everywhere. You can assume the area of the oceans is constant with depth. Use a value equal to the volume of the oceans divided by the initial value of h. Assume the ocean is fully drained when h = 1 m.

Bonus point: Does the assumption about ocean area cause your calculation to overestimate the time to drain the oceans, or underestimate it?

If you are beyond college freshman age, this quiz is not for you.

Re: 0969: "Delta-P"

Posted: Wed Oct 26, 2011 2:31 pm UTC
by Compdude
Isn't there a time-delay element too? I thought time passed more slowly in Narnia, so the effect of the water would be diminished.

Re: 0969: "Delta-P"

Posted: Wed Oct 26, 2011 2:33 pm UTC
by PolakoVoador
I was going to ask if this wouldn't dry our oceans after some time, but edbennion already gave us the numbers :D

Re: 0969: "Delta-P"

Posted: Wed Oct 26, 2011 2:37 pm UTC
by dp2
smikey wrote:
Vrishna wrote:
BrianB wrote:BTW - This is "Chronicles of Narnia"


Which is probably slightly more popular here, but nevertheless was completely ignored by me ... Is it worth reading or watching?


I'm not a Christian, and I really enjoyed the books as a kid. As an adult, I read them and was much less impressed. I will say this: the Christian allegories are by far the most interesting part of the books. Even not sharing the theology, that's an interesting and creative plotline.

The problem with the books is everything else. Other than Aslan, the only interesting character is probably Reepicheep, and maybe Polly and Digory. The Penvensies are almost uniformly boring, with only brief flashes from Lucy. The plots are simple and underwhelming, and there's really not a lot going on in any of them; they're all really novellas more than full books. The entire series is probably about the size of a middle-range Harry Potter book, and while length isn't everything, it leaves the books feeling rushed and oversimplified.

So in general: well-done symbolism (whether or not you agree with it), some very interesting world-building ideas that don't get enough attention, lousy characters, mediocre plots.

I AM a Christian, and I agree. "...Wardrobe" and "Dawn Treader" are good enough (the Dawn Treader movie left out the re-transformation, which scene was burned into my brain when I read it in fourth grade), and there are interesting ideas throughout, but as thrilling works of fantasy, they fall short. I don't even remember what happens in "The Silver Chair".

I wish people could get past books having Christian roots. Most of Western literature has one foot in Greek mythology, and what's the difference to an atheist or agnostic?

Re: 0969: "Delta-P"

Posted: Wed Oct 26, 2011 2:43 pm UTC
by hamjudo
The oceans contain about 1,300,000,000 cubic kilometers of salt water.

A cubic kilometer is 1,000,000,000 cubic meters.
A cubic meter is 1,000 liters

The flow rate is 400,000 liters per second.
Which is 400 cubic meters per second.
There are 30 days in a month, 24 hours in a day, 60 minutes in an hour, 60 seconds in a minute, so 2,592,000 seconds in a month.
400 cubic meters per second for a month is 1,036,800,000 cubic meters, or approximately 1 cubic kilometer.

If the flow rate was constant and the cupboard was moved as it drained each body of water, the oceans would be drained in 1,300,000,000 months, or about 1,000,000,000 years.

The cupboard would have significant local effects, but no short term significant global effects (on our globe).

The 200 meter per second water jet going into the cupboard would probably scour the neighboring sea floor, causing the cupboard to shift, and start sucking muck, until it hits bedrock that is too big to suck.

If the cupboard is near an undersea volcano, it could start sending lava to Narnia. The lava would cool on the other side, and eventually block the flow over there.

Re: 0969: "Delta-P"

Posted: Wed Oct 26, 2011 2:47 pm UTC
by ColinHeico
What about the time dilation from the real world time to Narnia time? If you'll remember the children lived long lives as kings and queens of Narnia in the space of a few earth hours. So figuring conservatively that they only lived 30 years in Narnia and were missing from Earth for a full 24 hours (pretty sure they were gone for much less, but like I said conservatively). So 30 years x 365.25 days per year divided by one day gives us 10,957.5 Narnia days to 1 Earth day in time compression.

So we can assume on the Narnia side the flow of 400,000 liters per Earth second would be no more then 36.5 liters per Narnia second (and probably considerably less!)

Re: 0969: "Delta-P"

Posted: Wed Oct 26, 2011 2:47 pm UTC
by Tr0ub4dor3
Unfortunately, the White Witch has some time to come up with a solution. Time in Narnia moves much faster than time on Earth, so the flow-rate would be significantly slowed.

If we assume that a few (2) months on Earth are equivalent to a few centuries on Narnia, then the flow rate of the water jet in Narnia gets reduced by a factor of [math](365*200)/(30*2)=1216.667[/math] and the flow rate in Narnia is actually only around 328.8 L/s. Enough to possibly create some basement leakage problem for any Narnians living near the portal, but not enough to make the White Witch sweat.

Re: 0969: "Delta-P"

Posted: Wed Oct 26, 2011 2:47 pm UTC
by Zylon
I'm going to assert that the math is completely superfluous to this strip, and thus actually makes it less funny. Just the image of dropping the wardrobe in the middle of the ocean with an anchor on it communicates everything needed to get the joke.

Re: 0969: "Delta-P"

Posted: Wed Oct 26, 2011 3:02 pm UTC
by Fire Brns
Grant10k wrote:Problem: Raising ocean levels due to climate change (Or impending Noah-esk flood, depending on how Christian you are).
Problem: White Witch.
Solution: Throw drain into ocean near the level we want our oceans to be. Retrieve drain when ocean reaches acceptable levels.

Speaking of fairy tales: Global warming. (don't call it "climate change" if you still want so say the sea is rising) During the height of Roman power the sea level was a least 2 feet higher. Almost immediately after the Ice age ended the sea level was 3 yards or 9 feet higher than it was today. Really what we need to worry about is tree huggers keeping us from having fun. (note: not written in a condescending tone)

To act like I really care: Narnian world was flat or something like that so the water would just flood off the edges draining our oceans near completely rather than drop our ocean a comfortable few feet.

Re: 0969: "Delta-P"

Posted: Wed Oct 26, 2011 3:03 pm UTC
by dp2
Zylon wrote:I'm going to assert that the math is completely superfluous to this strip, and thus actually makes it less funny. Just the image of dropping the wardrobe in the middle of the ocean with an anchor on it communicates everything needed to get the joke.

That would make it a Far Side comic. The math makes it an XKCD comic. It shows that the perpetrator used math and science to first figure out whether it would work.

Re: 0969: "Delta-P"

Posted: Wed Oct 26, 2011 3:04 pm UTC
by ChurchSkiz
So the solution to the White Witch is to flood and destroy all of Narnia? Why don't we just send in 4 kids and kick her ass?