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What-If 0041: "Go West"

Posted: Tue Apr 16, 2013 8:27 am UTC
by Quicksilver
If everybody in the US drove west, could we temporarily halt continental drift?
—Derek
http://what-if.xkcd.com/41/
Image
Alt Text: "two figures pondering windmills"
"It was only recently—in the mid-20th century—that we discovered that continents move at all, and we’re still getting a handle on the complex forces between the plates and currents in the mantle that control continental motion."
This is pretty much the kicker IMO. Without knowing the countless other factors that contribute to continent movement, it's hard to give any kind of estimate at all. Even assuming for every action there is an equal and opposite reaction, it's still unlikely much would happen.

Re: What-If 0041: "Go West"

Posted: Tue Apr 16, 2013 8:51 am UTC
by Klear
So... what can we do to make it move? Build a lot of rockets attached to the ground? We'd probably need to put some on other tectonic plates to counteract the effect it has on Earth.

Re: What-If 0041: "Go West"

Posted: Tue Apr 16, 2013 9:08 am UTC
by Xenomortis
What if we tried more power?

Re: What-If 0041: "Go West"

Posted: Tue Apr 16, 2013 11:07 am UTC
by peewee_RotA
This one has a couple of great quotes:

We don’t care how it works—we just want to know if we can break it.
if we charged a fair interest rate on the hour we gave up every spring we'd get 1.02 hours back every fall

Re: What-If 0041: "Go West"

Posted: Tue Apr 16, 2013 11:08 am UTC
by peewee_RotA
Klear wrote:So... what can we do to make it move? Build a lot of rockets attached to the ground? We'd probably need to put some on other tectonic plates to counteract the effect it has on Earth.


Might be more effective to attach all of the AK-47's to the ground and fire. :wink:

Re: What-If 0041: "Go West"

Posted: Tue Apr 16, 2013 11:41 am UTC
by PolakoVoador
peewee_RotA wrote:
Klear wrote:So... what can we do to make it move? Build a lot of rockets attached to the ground? We'd probably need to put some on other tectonic plates to counteract the effect it has on Earth.


Might be more effective to attach all of the AK-47's to the ground and fire. :wink:


What if all cars were electric, and powered by Yoda?

Re: What-If 0041: "Go West"

Posted: Tue Apr 16, 2013 12:12 pm UTC
by pkcommando
peewee_RotA wrote:
Klear wrote:So... what can we do to make it move? Build a lot of rockets attached to the ground? We'd probably need to put some on other tectonic plates to counteract the effect it has on Earth.


Might be more effective to attach all of the AK-47's to the ground and fire. :wink:

Pfft. The obvious answer is to do both. :wink:

With Super Hairdryer in there somewhere.

And get Yoda to push as well.

:D

Re: What-If 0041: "Go West"

Posted: Tue Apr 16, 2013 12:14 pm UTC
by peewee_RotA
pkcommando wrote:
peewee_RotA wrote:
Klear wrote:So... what can we do to make it move? Build a lot of rockets attached to the ground? We'd probably need to put some on other tectonic plates to counteract the effect it has on Earth.


Might be more effective to attach all of the AK-47's to the ground and fire. :wink:

Pfft. The obvious answer is to do both. :wink:

With Super Hairdryer in there somewhere.

And get Yoda to push as well.

:D


The yoda reference seems forced.

Re: What-If 0041: "Go West"

Posted: Tue Apr 16, 2013 1:30 pm UTC
by blowfishhootie
I remain disappointed by the What-If series. The answer to this one basically amounts to "we don't know and can't know (at this point in time)." So what was the point of it? Other, earlier ones could have similarly been dismissed, but the author took them to intentionally absurd levels of plausibility just for the hell of it, and it was interesting to read. That doesn't happen anymore. Is it a lack of interesting questions being submitted, or is it a lack of interest and effort on the author's part?

That said, the geographic population center of the US was really interesting and I'm glad he linked to it, I'd never seen that before.

Re: What-If 0041: "Go West"

Posted: Tue Apr 16, 2013 1:40 pm UTC
by cantab314
Randall has the plate thickness wrong. 35 km is about right for the continental crust, but the plate also includes the rigid upper part of the mantle. Together called the lithosphere, it's probably somewhere between 100 and 200 km thick under the continents (but thinner under the oceans).

Also, evidence points to the main force that moves the plates being "slab pull", the weight of the subducted part of a plate (which is denser than the surrounding mantle). Generally speaking the more of the edge of a plate is subducting, the faster it moves. A secondary force is "ridge push", the weight of the elevated ocean ridges (which are of course denser than the surrounding water). Basically the whole plate is high at one side, low at the other, so it slides downhill. Both forces are limited by the strength of faults the plate; if it's pulled or pushed too hard it will split apart or compress.

So to reverse the plate motion what we need isn't cars pushing it east, but balloons holding it up!

Re: What-If 0041: "Go West"

Posted: Tue Apr 16, 2013 2:29 pm UTC
by Fire Brns
cantab314 wrote:Also, evidence points to the main force that moves the plates being "slab pull"
Would we even be able to calculate the size of it? I mean, as more gets pulled under more get recycled and cuts it back down.

And I had a wonderful idea for a What If but forgot before I had a chance to write it down.

Re: What-If 0041: "Go West"

Posted: Tue Apr 16, 2013 2:37 pm UTC
by histrion
I'm curious - which song do you think he's referring to in the second alt-text? I mean, I know what song I'm thinking of, but I doubt Randall spent the same awful time as me trapped in the CCM ghetto in the 80s and 90s.

Re: What-If 0041: "Go West"

Posted: Tue Apr 16, 2013 2:59 pm UTC
by cantab314
Fire Brns wrote:
cantab314 wrote:Also, evidence points to the main force that moves the plates being "slab pull"
Would we even be able to calculate the size of it? I mean, as more gets pulled under more get recycled and cuts it back down.
We can use seismic tomography to map out the speeds of seismic waves in the deep Earth. Subducted plates (or 'slabs) show up as anomalies in that, since they're colder than the surrounding mantle. We can also determine the locations of deep earthquakes, that we believe must occur in the slab. There are some artifacts and gotchas in the data, but it's enough to make a decent estimate.

Re: What-If 0041: "Go West"

Posted: Tue Apr 16, 2013 3:30 pm UTC
by blowfishhootie
histrion wrote:I'm curious - which song do you think he's referring to in the second alt-text? I mean, I know what song I'm thinking of, but I doubt Randall spent the same awful time as me trapped in the CCM ghetto in the 80s and 90s.


The point of the joke lies in exactly the fact that there isn't a single song that can be the answer to this question.

Re: What-If 0041: "Go West"

Posted: Tue Apr 16, 2013 3:53 pm UTC
by peewee_RotA
blowfishhootie wrote:
histrion wrote:I'm curious - which song do you think he's referring to in the second alt-text? I mean, I know what song I'm thinking of, but I doubt Randall spent the same awful time as me trapped in the CCM ghetto in the 80s and 90s.


The point of the joke lies in exactly the fact that there isn't a single song that can be the answer to this question.


Not this? http://www.youtube.com/watch?v=1wc-AQJ2MYo

Re: What-If 0041: "Go West"

Posted: Tue Apr 16, 2013 4:16 pm UTC
by Klear
peewee_RotA wrote:
blowfishhootie wrote:
histrion wrote:I'm curious - which song do you think he's referring to in the second alt-text? I mean, I know what song I'm thinking of, but I doubt Randall spent the same awful time as me trapped in the CCM ghetto in the 80s and 90s.


The point of the joke lies in exactly the fact that there isn't a single song that can be the answer to this question.


Not this? http://www.youtube.com/watch?v=1wc-AQJ2MYo


Huh. I never knew the Pet Shot Boys version was a cover. In any case, I'm pretty sure this is the one, and I guess either version works, though I believe the PSB cover is a lot more famous.

Re: What-If 0041: "Go West"

Posted: Tue Apr 16, 2013 5:03 pm UTC
by blowfishhootie
Yeah I think you guys are right, now that I know that song exists. Pretty sure I've never heard it before. That'll teach me to open my big mouth*.


* - Actually, it probably won't.

Re: What-If 0041: "Go West"

Posted: Tue Apr 16, 2013 7:47 pm UTC
by WriteBrainedJR
peewee_RotA wrote:if we charged a fair interest rate on the hour we gave up every spring we'd get 1.02 hours back every fall

And THAT'S why it's called "daylight savings time," rather than "daylight loaning time."

Re: What-If 0041: "Go West"

Posted: Tue Apr 16, 2013 7:59 pm UTC
by PsiSquared
"Given a density of about 2.7 kg/Liter, its mass is probably in the neighborhood of 2.3x1021kg, so it outweighs our fleet by a factor of about six trillion."

Shouldn't it be six billion?

(2.3x1021kg)/(4x1011kg) = 6x109

Doesn't really matter, since this figure is never used afterwards, but still:
http://xkcd.com/386/

Re: What-If 0041: "Go West"

Posted: Wed Apr 17, 2013 3:41 am UTC
by willpellmn
Since the US population is apparently migrating westward 525960 times as fast as the continent, let's speculate about how long it will take for their accumulated mass to tip the tectonic plate a visible distance to the side. Given the rate at which trailer park residents reproduce, it shouldn't take terribly long....

What's the song that's stuck in everyone's head? The only one that springs to my mind is by Fear Factory covering Gary Numan....

And is this comic Randal's ever so subtle way of jumping on the end-DST bandwagon? If so, I heartily approve.

Re: What-If 0041: "Go West"

Posted: Wed Apr 17, 2013 4:13 am UTC
by Eshru
So, what if we all drove 18 wheelers? Fully loaded.

Re: What-If 0041: "Go West"

Posted: Wed Apr 17, 2013 4:15 am UTC
by RogueCynic
What happened to the philosophic question:"If everyone in the US jumped at the same time, what would happen?"? I'd like to take this opportunity to propose a controversial theory. Continental drift could explain climate change. If the continent drifts south, we'll be getting more of the sun's warmth.

Re: What-If 0041: "Go West"

Posted: Wed Apr 17, 2013 6:30 am UTC
by aewgliriel
I apparently have not posted enough to be allowed links, but my first thought was Go West's "King Of Wishful Thinking".

Re: What-If 0041: "Go West"

Posted: Wed Apr 17, 2013 6:32 am UTC
by keithl
At the 39th parallel, we are rotating around the earth's axis at 465.1*cos(39°) = 361.5 m/s . If we want to slow the world's rotation, we drive south to the equator, adding to the moment of inertia. Since the angular momentum stays constant, angular velocity must decrease. Driving north towards the pole works vice-versa, and we get about 80% of the effect if we stop at Prudhoe Bay.

A larger effect would result if our cars created enough CO₂ to slightly warm the earth, ocean, and atmosphere. All that material thermally expands over a very long time, eventually increasing the moment of inertia of the planet more than car movement could, slowing the earth down more. I would share my truly marvelous calculations, but they won't fit in the margin of this web page.

Re: What-If 0041: "Go West"

Posted: Wed Apr 17, 2013 7:14 am UTC
by keithl
Xenomortis wrote:What if we tried more power?

Good point. If we all drove west at relativistic speeds, 99.9% of the speed of light, spaced one second apart so there is time for the rock to vaporize, the energy release from 4E11kg of car and driver will be about 1.8e30J. If 8% of that energy vaporizes continental rock to thermal velocities of 11km/s, it will escape into space. If we distribute the energy properly, it could loft 2.3e21 kg into space, and eliminate North American continental drift by eliminating the North American continent.

Re: What-If 0041: "Go West"

Posted: Thu Apr 18, 2013 12:33 pm UTC
by peewee_RotA
WriteBrainedJR wrote:
peewee_RotA wrote:if we charged a fair interest rate on the hour we gave up every spring we'd get 1.02 hours back every fall

And THAT'S why it's called "daylight savings time," rather than "daylight loaning time."


Interesting

Re: What-If 0041: "Go West"

Posted: Thu Apr 18, 2013 12:59 pm UTC
by peewee_RotA
Klear wrote:
peewee_RotA wrote:
blowfishhootie wrote:
histrion wrote:I'm curious - which song do you think he's referring to in the second alt-text? I mean, I know what song I'm thinking of, but I doubt Randall spent the same awful time as me trapped in the CCM ghetto in the 80s and 90s.


The point of the joke lies in exactly the fact that there isn't a single song that can be the answer to this question.


Not this? http://www.youtube.com/watch?v=1wc-AQJ2MYo


Huh. I never knew the Pet Shot Boys version was a cover. In any case, I'm pretty sure this is the one, and I guess either version works, though I believe the PSB cover is a lot more famous.


I had never heard either until googling this. I was a much happier person before watching it. Eyebleach may be in order.

Re: What-If 0041: "Go West"

Posted: Thu Apr 18, 2013 1:57 pm UTC
by Klear
peewee_RotA wrote:
Klear wrote:Huh. I never knew the Pet Shot Boys version was a cover. In any case, I'm pretty sure this is the one, and I guess either version works, though I believe the PSB cover is a lot more famous.


I had never heard either until googling this. I was a much happier person before watching it. Eyebleach may be in order.


What are you talking about? That music video is awesome! Maybe it's just better to see it in former communist country shortly after revolution... The timing of that cover was just perfect.

Re: What-If 0041: "Go West"

Posted: Thu Apr 18, 2013 4:14 pm UTC
by peewee_RotA
Klear wrote:
peewee_RotA wrote:
Klear wrote:Huh. I never knew the Pet Shot Boys version was a cover. In any case, I'm pretty sure this is the one, and I guess either version works, though I believe the PSB cover is a lot more famous.


I had never heard either until googling this. I was a much happier person before watching it. Eyebleach may be in order.


What are you talking about? That music video is awesome! Maybe it's just better to see it in former communist country shortly after revolution... The timing of that cover was just perfect.


Video not available in my country. :P

Re: What-If 0041: "Go West"

Posted: Thu Apr 18, 2013 9:51 pm UTC
by Klear
peewee_RotA wrote:
Klear wrote:
peewee_RotA wrote:
Klear wrote:Huh. I never knew the Pet Shot Boys version was a cover. In any case, I'm pretty sure this is the one, and I guess either version works, though I believe the PSB cover is a lot more famous.


I had never heard either until googling this. I was a much happier person before watching it. Eyebleach may be in order.


What are you talking about? That music video is awesome! Maybe it's just better to see it in former communist country shortly after revolution... The timing of that cover was just perfect.


Video not available in my country. :P


This this.

Re: What-If 0041: "Go West"

Posted: Thu Apr 18, 2013 10:45 pm UTC
by gordo
keithl wrote:I would share my truly marvelous calculations, but they won't fit in the margin of this web page.


+1 internet for you, sir!