# ­xkcd thread **URL:** \ **Category:** Cafe Society\ **Tags:** comic-strips\ **Created:** [May 28, 2020, 12:57am UTC](https://boards.straightdope.com/t/xkcd-thread/854574 "2020-05-28T00:57:03Z")\ **Posts on this page:** 20\ **Page:** 23
**Author:** ![LSLGuy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lslguy/32/5813_2.png) [@LSLGuy](https://boards.straightdope.com/u/LSLGuy)\ **Post date:** [January 17, 2021, 11:27pm UTC](https://boards.straightdope.com/t/xkcd-thread/854574/441 "2021-01-17T23:27:07Z")
Heck, just write your text message on a piece of paper, attach it to a rock and throw it to them. Much cheaper than Verizon! ---
**Author:** ![RTFirefly](https://avatars.discourse-cdn.com/v4/letter/r/c77e96/32.png) [@RTFirefly](https://boards.straightdope.com/u/RTFirefly)\ **Post date:** [January 18, 2021, 1:49am UTC](https://boards.straightdope.com/t/xkcd-thread/854574/442 "2021-01-18T01:49:04Z")
Also, it wouldn’t take gases to give you a sense that the ground is tilting away from you - it really _would_ be. ---
**Author:** ![dtilque](https://avatars.discourse-cdn.com/v4/letter/d/d6d6ee/32.png) [@dtilque](https://boards.straightdope.com/u/dtilque)\ **Post date:** [January 19, 2021, 7:20am UTC](https://boards.straightdope.com/t/xkcd-thread/854574/443 "2021-01-19T07:20:03Z")
> **[Pulsar Analogy](https://xkcd.com/2413/)** > > The #2 cause of astronomer hand injuries is trying to do vector math when the second axis points off to the right. ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [January 19, 2021, 11:49am UTC](https://boards.straightdope.com/t/xkcd-thread/854574/444 "2021-01-19T11:49:09Z")
The premise is that these scale models are built on Earth, so they would need artificial gravity to make the ground actually tilt away. They don’t have that, so they need to simulate the effect in some other way, for an accurate experience. It remains unstated how they’re simulating the thinning atmosphere, aurorae, storm clouds, etc. ---
**Author:** ![Kzbre5m](https://avatars.discourse-cdn.com/v4/letter/k/f08c70/32.png) [@Kzbre5m](https://boards.straightdope.com/u/Kzbre5m)\ **Post date:** [January 19, 2021, 12:39pm UTC](https://boards.straightdope.com/t/xkcd-thread/854574/445 "2021-01-19T12:39:15Z")
Having used self-retracting metal tape measures for many years, it does not spin until it’s totally retracted, therefore the tape doesn’t smack anything. It’s the sudden stopping (probably the hook hitting the case) that makes it spin, not the retracting. Other than that, it’s pretty accurate. Also, not a good idea to let it retract the whole or most of the tape, as the rivets that hold the hook end eventually shear off the blade. ---
**Author:** ![RTFirefly](https://avatars.discourse-cdn.com/v4/letter/r/c77e96/32.png) [@RTFirefly](https://boards.straightdope.com/u/RTFirefly)\ **Post date:** [January 19, 2021, 3:24pm UTC](https://boards.straightdope.com/t/xkcd-thread/854574/446 "2021-01-19T15:24:59Z")
> [@Chronos](#): > > The premise is that these scale models are built on Earth, so they would need artificial gravity to make the ground actually tilt away. I disagree that being built on Earth is a necessary premise. And either way, if they’re a scale model, the ground would **have** to visibly tilt away. Even the 1/10,000 scale model is only 2.5 miles in circumference. You’d see that drop. ---
**Author:** ![TroutMan](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/troutman/32/6721_2.png) [@TroutMan](https://boards.straightdope.com/u/TroutMan)\ **Post date:** [January 19, 2021, 4:05pm UTC](https://boards.straightdope.com/t/xkcd-thread/854574/447 "2021-01-19T16:05:42Z")
> [@RTFirefly](#): > > if they’re a scale model, the ground would **have** to visibly tilt away. The ground could tilt away, but the direction of gravity wouldn’t follow the curve. Chronos’ point is that artificial gravity would be needed to maintain the downward force at 90° at any point of the curve. ---
**Author:** ![GreenWyvern](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/greenwyvern/32/2834_2.png) [@GreenWyvern](https://boards.straightdope.com/u/GreenWyvern)\ **Post date:** [January 19, 2021, 4:20pm UTC](https://boards.straightdope.com/t/xkcd-thread/854574/448 "2021-01-19T16:20:21Z")
> [@RTFirefly](#): > > I disagree that being built on Earth is a necessary premise.   Asteroid B-612? [![](https://lithub.com/wp-content/uploads/2018/04/The-Little-Prince-1.jpg) ](https://lithub.com/wp-content/uploads/2018/04/The-Little-Prince-1.jpg) ---
**Author:** ![RTFirefly](https://avatars.discourse-cdn.com/v4/letter/r/c77e96/32.png) [@RTFirefly](https://boards.straightdope.com/u/RTFirefly)\ **Post date:** [January 19, 2021, 6:03pm UTC](https://boards.straightdope.com/t/xkcd-thread/854574/449 "2021-01-19T18:03:58Z")
> [@TroutMan](#): > > The ground could tilt away, but the direction of gravity wouldn’t follow the curve. Chronos’ point is that artificial gravity would be needed to maintain the downward force at 90° at any point of the curve. First, that’s not what Chronos said. He said the ground _wouldn’t_ tilt away, and his comment doesn’t appear to make any sense if he isn’t talking about the ground _of the model_. It _has_ to tilt away. Second, if one accepts the premise of the model sitting on the surface of the earth somewhere like a huge ball bearing, then it’s not the hypothetical world Munroe is imagining. Oxygen is never a problem, for one thing, nor is cell phone service. Here’s my much simpler premise: they’re of an Earth Mark Two (or Three) where the copies of the Earth are identical to our planet (maybe part of a Solar system Mark Two or Three), but when we visit **we** become 10,000 (or 100,000) times as big. Then AFAICT, everything works, other than real people can’t really visit because we can’t suddenly become 10,000x or 100,000x as big. It’s a game of Randall Munroe’s imagination to begin with, of course, so really there’s no need for a premise at all; it’s impossible no matter what premise one starts off with. Either people can’t visit regardless, or the 1/whichever world won’t work the way he describes. But the premise shouldn’t introduce a host of new problems. ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [January 19, 2021, 9:12pm UTC](https://boards.straightdope.com/t/xkcd-thread/854574/450 "2021-01-19T21:12:13Z")
The ground wouldn’t tilt away if you keep the ground surface perpendicular to gravity, which I was assuming the model-maker was doing. ---
**Author:** ![RTFirefly](https://avatars.discourse-cdn.com/v4/letter/r/c77e96/32.png) [@RTFirefly](https://boards.straightdope.com/u/RTFirefly)\ **Post date:** [January 20, 2021, 2:07am UTC](https://boards.straightdope.com/t/xkcd-thread/854574/451 "2021-01-20T02:07:45Z")
When a ship ‘sinks the land,’ it’s because the ground (or in this case the surface of the ocean) slightly but visibly tilts away, here on this Earth we actually inhabit. And on this Earth, the ground surface is perpendicular to gravity. ---
**Author:** ![dtilque](https://avatars.discourse-cdn.com/v4/letter/d/d6d6ee/32.png) [@dtilque](https://boards.straightdope.com/u/dtilque)\ **Post date:** [January 21, 2021, 3:17am UTC](https://boards.straightdope.com/t/xkcd-thread/854574/452 "2021-01-21T03:17:42Z")
> **[Solar System Compression Artifacts](https://xkcd.com/2414/)** > > Most of our universe consists of dark matter rendered completely undetectable by our spacetime codec's dynamic range issues. ---
**Author:** ![BigT](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/bigt/32/12044_2.png) [@BigT](https://boards.straightdope.com/u/BigT)\ **Post date:** [January 21, 2021, 3:30am UTC](https://boards.straightdope.com/t/xkcd-thread/854574/453 "2021-01-21T03:30:28Z")
> [@RTFirefly](#): > > When a ship ‘sinks the land,’ it’s because the ground (or in this case the surface of the ocean) slightly but visibly tilts away, here on this Earth we actually inhabit. And on this Earth, the ground surface is perpendicular to gravity. Yes, but the model appears to show something with Earth-level gravity. That wouldn’t be true on a 1/10000 model planet, so the model is most likely still on the surface of a larger planet. And, in that case, either the model doesn’t curve, or gravity will not remain perpendicular when it does. I would expect that an actual scale model made like this (minus the parts that are impossible) would in fact be on earth, and would in fact not curve. It would just take up 1/10000th of the Earth’s surface. That is, assuming it’s not all virtual. Then you can do whatever you want. ---
**Author:** ![Ponderoid](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/ponderoid/32/19221_2.png) [@Ponderoid](https://boards.straightdope.com/u/Ponderoid)\ **Post date:** [January 21, 2021, 5:47am UTC](https://boards.straightdope.com/t/xkcd-thread/854574/454 "2021-01-21T05:47:30Z")
I laughed out loud at this one. I recall reading a theory many moons ago that all the various counterintuitive results of quantum mechanics are because it’s impossible to get infinite precision out of a real world computation. ---
**Author:** ![RTFirefly](https://avatars.discourse-cdn.com/v4/letter/r/c77e96/32.png) [@RTFirefly](https://boards.straightdope.com/u/RTFirefly)\ **Post date:** [January 22, 2021, 1:15am UTC](https://boards.straightdope.com/t/xkcd-thread/854574/455 "2021-01-22T01:15:52Z")
> [@BigT](#): > > I would expect that an actual scale model made like this (minus the parts that are impossible) would in fact be on earth, and would in fact not curve. It would just take up 1/10000th of the Earth’s surface. It would not be a scale model, then, because you can’t do a flat scale model of a sphere, as noted by mapmakers for pretty much forever. You can choose to preserve some properties, but never all of them. Simpler just to assume an Earth-sized and -shaped model of Earth, with visiting humans somehow being 10,000x or 100,000x as big as normal. Then gravity, atmosphere, etc. need no workarounds. ---
**Author:** ![LSLGuy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lslguy/32/5813_2.png) [@LSLGuy](https://boards.straightdope.com/u/LSLGuy)\ **Post date:** [January 22, 2021, 1:29am UTC](https://boards.straightdope.com/t/xkcd-thread/854574/456 "2021-01-22T01:29:14Z")
Of course that approach fails just as badly, albeit in different ways. e.g. crank the human up to 10K x normal. And watch their feet crush right through the real Earth’s crust down into the mantle due to the enormous weight per unit area. Of course the human itself would fail into a quivering lump of ooze; bone doesn’t scale to 10Kx either. Etc. ---
**Author:** ![RTFirefly](https://avatars.discourse-cdn.com/v4/letter/r/c77e96/32.png) [@RTFirefly](https://boards.straightdope.com/u/RTFirefly)\ **Post date:** [January 22, 2021, 12:01pm UTC](https://boards.straightdope.com/t/xkcd-thread/854574/457 "2021-01-22T12:01:55Z")
Oh yeah, the _human_ fails, but at least the Earth itself works without a whole bunch of jury-rigging. ---
**Author:** ![RTFirefly](https://avatars.discourse-cdn.com/v4/letter/r/c77e96/32.png) [@RTFirefly](https://boards.straightdope.com/u/RTFirefly)\ **Post date:** [January 22, 2021, 5:05pm UTC](https://boards.straightdope.com/t/xkcd-thread/854574/458 "2021-01-22T17:05:57Z")
> [@LSLGuy](#): > > crank the human up to 10K x normal. And watch their feet crush right through the real Earth’s crust down into the mantle due to the enormous weight per unit area. > > Of course the human itself would fail into a quivering lump of ooze; bone doesn’t scale to 10Kx either. Couldn’t resist coming back to this. Biological systems don’t scale up well, so the latter comment is definitely true. But how about the weight? Let’s assume for this question that my body miraculously scales up without problems. I’m assuming that if I were 10,000 times as tall, and my other dimensions grew proportionately, then instead of weighing 180 pounds, I’d weigh 180\*10,000^3 pounds, or 90 billion tons. But my currently size 12 feet would each cover about a square mile, so the question would be: what happens here on regular Earth when there’s 45 billion tons sitting on a square mile of land? Has anything like this come close to happening? How heavy, for instance, is a square mile of Kilimanjaro? ---
**Author:** ![Dr.Winston\_OBoogie](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dr.winston_oboogie/32/2945_2.png) [@Dr.Winston\_OBoogie](https://boards.straightdope.com/u/Dr.Winston_OBoogie)\ **Post date:** [January 22, 2021, 5:08pm UTC](https://boards.straightdope.com/t/xkcd-thread/854574/459 "2021-01-22T17:08:55Z")
> [@LSLGuy](#): > > Of course the human itself would fail into a quivering lump of ooze; bone doesn’t scale to 10Kx either. Boy, doesn’t this sound like one of his “What If” scenarios? I always liked the mole of moles. ---
**Author:** ![smithsb](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/smithsb/32/12107_2.png) [@smithsb](https://boards.straightdope.com/u/smithsb)\ **Post date:** [January 22, 2021, 8:44pm UTC](https://boards.straightdope.com/t/xkcd-thread/854574/460 "2021-01-22T20:44:21Z")
Mauna Loa is approximately 75,000 cubic kilometers. Density of basalt is 2.9-3.0g/cubic centimeter. Doing some math and conversions (arrrrggh) All that weight depresses the earth’s crust another 8 kilometers. But you’re displacing water and gravity varies with distance from the earth’s center. Sorry, my head hurts. [Previous page](https://boards.straightdope.com/t/xkcd-thread/854574.md?page=22) [Next page](https://boards.straightdope.com/t/xkcd-thread/854574.md?page=24)