# Is there an object that meets this description? **URL:** \ **Category:** In My Humble Opinion\ **Created:** [January 17, 2016, 8:56pm UTC](https://boards.straightdope.com/t/is-there-an-object-that-meets-this-description/743436 "2016-01-17T20:56:04Z")\ **Posts on this page:** 14\ **Page:** 2
**Author:** ![WhyNot](https://avatars.discourse-cdn.com/v4/letter/w/c77e96/32.png) [@WhyNot](https://boards.straightdope.com/u/WhyNot)\ **Post date:** [January 18, 2016, 4:27am UTC](https://boards.straightdope.com/t/is-there-an-object-that-meets-this-description/743436/21 "2016-01-18T04:27:09Z")
Or a large [sunhat](http://www.beltoutlet.com/exlabrshsunh.html)? ---
**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 18, 2016, 4:38am UTC](https://boards.straightdope.com/t/is-there-an-object-that-meets-this-description/743436/22 "2016-01-18T04:38:45Z")
> [@](#): > > Quoth **Peter Morris** : > > Let me guess … the lesson is explaining how Space-time is deformed by massive objects? Yup, and how geodesics look in curved spaces. That’s what the tape is for: Stick tape smoothly onto a curved surface, and it’ll follow a geodesic. ---
**Author:** ![Peter\_Morris](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/peter_morris/32/359_2.png) [@Peter\_Morris](https://boards.straightdope.com/u/Peter_Morris)\ **Post date:** [January 18, 2016, 4:45am UTC](https://boards.straightdope.com/t/is-there-an-object-that-meets-this-description/743436/23 "2016-01-18T04:45:33Z")
If you have a local glassmaker, you might be able to get an uncut [bullion or bullseye.](https://www.thevictorianemporium.com/store/product/glass_bullion)(They are used in making [faux antique windows](https://s-media-cache-ak0.pinimg.com/736x/87/d6/b0/87d6b09dcc61da3ac216ccc5ccc4d3fc.jpg)) Maybe it comes in a material that is safe for children to handle. ---
**Author:** ![Peter\_Morris](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/peter_morris/32/359_2.png) [@Peter\_Morris](https://boards.straightdope.com/u/Peter_Morris)\ **Post date:** [January 18, 2016, 5:02am UTC](https://boards.straightdope.com/t/is-there-an-object-that-meets-this-description/743436/24 "2016-01-18T05:02:24Z")
Maybe you can make one of [these models](https://www.youtube.com/watch?v=MTY1Kje0yLg). Guy said it cost him 20 bucks. ---
**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 18, 2016, 5:24am UTC](https://boards.straightdope.com/t/is-there-an-object-that-meets-this-description/743436/25 "2016-01-18T05:24:59Z")
Ooh, the glass bullion looks perfect. It’s way too expensive, and I wouldn’t trust middle-schoolers not to drop it, but at least now I know what to call this thing if I make one out of plexiglass. ---
**Author:** ![chappachula](https://avatars.discourse-cdn.com/v4/letter/c/d2c977/32.png) [@chappachula](https://boards.straightdope.com/u/chappachula)\ **Post date:** [January 18, 2016, 12:47pm UTC](https://boards.straightdope.com/t/is-there-an-object-that-meets-this-description/743436/26 "2016-01-18T12:47:29Z")
> [@Chronos](#): > > Yup, and how geodesics look in curved spaces. That’s what the tape is for: Stick tape smoothly onto a curved surface, and it’ll follow a geodesic. You are teaching this lesson to children? what age are they? That sounds like advanced high-school geometry ---
**Author:** ![Fear\_Itself](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/fear_itself/32/19637_2.png) [@Fear\_Itself](https://boards.straightdope.com/u/Fear_Itself)\ **Post date:** [January 18, 2016, 1:05pm UTC](https://boards.straightdope.com/t/is-there-an-object-that-meets-this-description/743436/27 "2016-01-18T13:05:28Z")
Here is a plastic mold for making the halves for [chocolate spheres.](http://www.amazon.com/CK-Products-8-Inch-Ball-Chocolate/dp/B003QP3ILY/ref=sr_1_fkmr1_1?ie=UTF8&qid=1453122352&sr=8-1-fkmr1&keywords=plaster+mold+half+ball) The bulge is a hemisphere, don’t know if that is too big for your purposes. ---
**Author:** ![quiltguy](https://avatars.discourse-cdn.com/v4/letter/q/e47774/32.png) [@quiltguy](https://boards.straightdope.com/u/quiltguy)\ **Post date:** [January 18, 2016, 1:51pm UTC](https://boards.straightdope.com/t/is-there-an-object-that-meets-this-description/743436/28 "2016-01-18T13:51:18Z")
[QUOTE=Chronos And I thought about papier-mache, but that probably wouldn’t take well to masking tape being repeatedly applied and pulled off. Hence the mucilage, to provide protection and slide-ability. Epoxy would work too, and make the project even stronger. ---
**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 18, 2016, 3:49pm UTC](https://boards.straightdope.com/t/is-there-an-object-that-meets-this-description/743436/29 "2016-01-18T15:49:37Z")
> [@](#): > > You are teaching this lesson to children? what age are they? > That sounds like advanced high-school geometry I don’t know of any way to approach the problem that’s at the advanced high school level. You can do it with tensor calculus, which is college level, or you can do it by sticking tape on physical objects, which is accessible to kids. Take a strip of tape about as long as the width of the curved object, put it on starting at the edge of the object, and aim close to the bulge but a little off-center. Apply the tape smoothly, without wrinkling it, and it’ll follow a geodesic on the surface. After you’ve done this, take a look at the tape you’ve put on, and you’ll find that it bends around the bulge. The actual activity would have a bit more build-up than this, involving flat maps and globes and stretched string and so on, but that’s the gist of it. EDIT: Does “mucilage” have some specific meaning in a craft context? Looking online, it seems to just be a catch-all term for “gooey organic matter”. ---
**Author:** ![Peter\_Morris](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/peter_morris/32/359_2.png) [@Peter\_Morris](https://boards.straightdope.com/u/Peter_Morris)\ **Post date:** [January 18, 2016, 5:01pm UTC](https://boards.straightdope.com/t/is-there-an-object-that-meets-this-description/743436/30 "2016-01-18T17:01:17Z")
> [@Peter\_Morris](#): > > Maybe you can make one of [these models](https://www.youtube.com/watch?v=MTY1Kje0yLg). Guy said it cost him 20 bucks. Correction, the spandex was $20, the whole thing about $100. ---
**Author:** ![The\_Hamster\_King](https://avatars.discourse-cdn.com/v4/letter/t/8edcca/32.png) [@The\_Hamster\_King](https://boards.straightdope.com/u/The_Hamster_King)\ **Post date:** [January 18, 2016, 5:01pm UTC](https://boards.straightdope.com/t/is-there-an-object-that-meets-this-description/743436/31 "2016-01-18T17:01:48Z")
> [@Ignotus](#): > > I clearly remember Don Quixote wearing a helmet that fits the description on some illustration in the copy of Cervantes I read as a child; but I doubt you could find an actual specimen today, unless perhaps some medieval reenactor has one. Don Quixote’s helmet is [a shaving basin](https://www.google.com/search?q=shaving+basin&biw=2144&bih=1030&source=lnms&tbm=isch&sa=X&ved=0ahUKEwjnxqS867PKAhVC1GMKHdT2AnkQ_AUIBygC&dpr=0.9). ---
**Author:** ![gigi](https://avatars.discourse-cdn.com/v4/letter/g/a587f6/32.png) [@gigi](https://boards.straightdope.com/u/gigi)\ **Post date:** [January 18, 2016, 5:37pm UTC](https://boards.straightdope.com/t/is-there-an-object-that-meets-this-description/743436/32 "2016-01-18T17:37:14Z")
> [@Chronos](#): > > EDIT: Does “mucilage” have some specific meaning in a craft context? Looking online, it seems to just be a catch-all term for “gooey organic matter”. Yes, it’s a kind of craft glue good for collages. [![](http://content.etilize.com/900/1011915619.jpg) ](http://content.etilize.com/900/1011915619.jpg) ---
**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 20, 2016, 2:14am UTC](https://boards.straightdope.com/t/is-there-an-object-that-meets-this-description/743436/33 "2016-01-20T02:14:13Z")
Update: I mentioned this to one of my colleagues, and he thinks that making these things would be a good project for his students. So we’re killing two birds with ein stein. ---
**Author:** ![Isilder](https://avatars.discourse-cdn.com/v4/letter/i/cc9497/32.png) [@Isilder](https://boards.straightdope.com/u/Isilder)\ **Post date:** [January 21, 2016, 9:31am UTC](https://boards.straightdope.com/t/is-there-an-object-that-meets-this-description/743436/34 "2016-01-21T09:31:56Z")
> [@Chronos](#): > > Update: I mentioned this to one of my colleagues, and he thinks that making these things would be a good project for his students. So we’re killing two birds with ein stein. What about cymbals… as in musical, part of a drummers set… [Previous page](https://boards.straightdope.com/t/is-there-an-object-that-meets-this-description/743436.md?page=1)