# Does a Drinking Straw Have One Hole or Two? **URL:** \ **Category:** In My Humble Opinion\ **Created:** [March 13, 2018, 12:08pm UTC](https://boards.straightdope.com/t/does-a-drinking-straw-have-one-hole-or-two/810479 "2018-03-13T12:08:57Z")\ **Posts on this page:** 20\ **Page:** 3
**Author:** ![jtur88](https://avatars.discourse-cdn.com/v4/letter/j/e9c0ed/32.png) [@jtur88](https://boards.straightdope.com/u/jtur88)\ **Post date:** [March 14, 2018, 8:28am UTC](https://boards.straightdope.com/t/does-a-drinking-straw-have-one-hole-or-two/810479/41 "2018-03-14T08:28:01Z")
It’s a hollow cylinder with a hole at each end. It’s an extremely thick or concave disc with a hole through the center. Neither answer is wrong. ---
**Author:** ![Johanna](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/johanna/32/8318_2.png) [@Johanna](https://boards.straightdope.com/u/Johanna)\ **Post date:** [March 14, 2018, 10:28am UTC](https://boards.straightdope.com/t/does-a-drinking-straw-have-one-hole-or-two/810479/42 "2018-03-14T10:28:26Z")
> [@BobBitchin](#): > > There is no hole. Do not try to bend the hole—that’s impossible. Instead, only try to realize the truth: there is no hole. ---
**Author:** ![don\_t\_ask](https://avatars.discourse-cdn.com/v4/letter/d/e68b1a/32.png) [@don\_t\_ask](https://boards.straightdope.com/u/don_t_ask)\ **Post date:** [March 14, 2018, 10:36am UTC](https://boards.straightdope.com/t/does-a-drinking-straw-have-one-hole-or-two/810479/43 "2018-03-14T10:36:57Z")
A straw is simply a complete fistula with two openings but no holes. ---
**Author:** ![Napier](https://avatars.discourse-cdn.com/v4/letter/n/ce73a5/32.png) [@Napier](https://boards.straightdope.com/u/Napier)\ **Post date:** [March 14, 2018, 3:05pm UTC](https://boards.straightdope.com/t/does-a-drinking-straw-have-one-hole-or-two/810479/44 "2018-03-14T15:05:37Z")
> [@Fear\_Itself](#): > > Two. Only a person who thinks his lips and his anus are the same thing could think otherwise. So, how are things in Flavortown, anyway? ---
**Author:** ![Mangetout](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mangetout/32/19_2.png) [@Mangetout](https://boards.straightdope.com/u/Mangetout)\ **Post date:** [March 14, 2018, 3:10pm UTC](https://boards.straightdope.com/t/does-a-drinking-straw-have-one-hole-or-two/810479/45 "2018-03-14T15:10:00Z")
> [@Fear\_Itself](#): > > Two. Only a person who thinks his lips and his anus are the same thing could think otherwise. Funny, but not really. The two faces of a washer are separate things from each other, but there is one hole. The human digestive system is a single hole that penetrates the body from one opening (lips) to another opening (anus) ---
**Author:** ![TreacherousCretin](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/treacherouscretin/32/476_2.png) [@TreacherousCretin](https://boards.straightdope.com/u/TreacherousCretin)\ **Post date:** [March 14, 2018, 4:37pm UTC](https://boards.straightdope.com/t/does-a-drinking-straw-have-one-hole-or-two/810479/46 "2018-03-14T16:37:28Z")
> [@eschereal](#): > > A straw **is** a hole. With sides. This is what I was going to post. ---
**Author:** ![eschereal](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/eschereal/32/18939_2.png) [@eschereal](https://boards.straightdope.com/u/eschereal)\ **Post date:** [March 14, 2018, 5:11pm UTC](https://boards.straightdope.com/t/does-a-drinking-straw-have-one-hole-or-two/810479/47 "2018-03-14T17:11:42Z")
> [@Mangetout](#): > > I would argue that yes, in fact they do - plastic drinking straws are continuously extruded via a die - that is, a ‘solid’ stream of plastic is parted by a central plug in the die to create the hole. There isn’t a lot of difference between:h > > Pushing a drill through a solid material > vs > Pushing a stream of material over a central plug I am young enough to remember paper straws, which were made by spiral-wrapping a 2" ribbon of wax-coated paper around a mandrel, heat-sealed at the seam and cut into appropriate length segments. Not very analogous to drilling. ---
**Author:** ![Mangetout](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mangetout/32/19_2.png) [@Mangetout](https://boards.straightdope.com/u/Mangetout)\ **Post date:** [March 14, 2018, 5:41pm UTC](https://boards.straightdope.com/t/does-a-drinking-straw-have-one-hole-or-two/810479/48 "2018-03-14T17:41:44Z")
I also am old enough, and I did think about paper straws, but as I was responding to a post talking about nearly all straws _not_ being drilled. ---
**Author:** ![DPRK](https://avatars.discourse-cdn.com/v4/letter/d/4491bb/32.png) [@DPRK](https://boards.straightdope.com/u/DPRK)\ **Post date:** [March 14, 2018, 5:50pm UTC](https://boards.straightdope.com/t/does-a-drinking-straw-have-one-hole-or-two/810479/49 "2018-03-14T17:50:35Z")
> [@Mangetout](#): > > I agree on all of this and I am trying to resolve how we count the holes in a different object (I have only a superficial understanding of topology). Imagine a solid ball into which we drill three times, at points equidistant along the equator, toward the centre and meeting at the core. There are three openings, all of which are linked to one another internally - how many holes are there? (I don’t know) Aren’t there two holes, in the sense a disc with two smaller discs stamped out of it has two holes, or a solid ball drilled from the surface only down to the center and not all the way through has no holes? ---
**Author:** ![Rysto](https://avatars.discourse-cdn.com/v4/letter/r/ecccb3/32.png) [@Rysto](https://boards.straightdope.com/u/Rysto)\ **Post date:** [March 14, 2018, 5:53pm UTC](https://boards.straightdope.com/t/does-a-drinking-straw-have-one-hole-or-two/810479/50 "2018-03-14T17:53:21Z")
Topologically, a straw is equivalent to a donut. A donut has one hole. QED ---
**Author:** ![Musicat](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/musicat/32/20189_2.png) [@Musicat](https://boards.straightdope.com/u/Musicat)\ **Post date:** [March 14, 2018, 5:55pm UTC](https://boards.straightdope.com/t/does-a-drinking-straw-have-one-hole-or-two/810479/51 "2018-03-14T17:55:52Z")
> [@Mangetout](#): > > I agree on all of this and I am trying to resolve how we count the holes in a different object (I have only a superficial understanding of topology). Imagine a solid ball into which we drill three times, at points equidistant along the equator, toward the centre and meeting at the core. There are three openings, all of which are linked to one another internally - how many holes are there? (I don’t know) An opening is not a hole. In this case, you have 3 openings, 1 hole. In the straw question, 2 openings, 1 hole. Same for a donut. ---
**Author:** ![DPRK](https://avatars.discourse-cdn.com/v4/letter/d/4491bb/32.png) [@DPRK](https://boards.straightdope.com/u/DPRK)\ **Post date:** [March 14, 2018, 6:06pm UTC](https://boards.straightdope.com/t/does-a-drinking-straw-have-one-hole-or-two/810479/52 "2018-03-14T18:06:00Z")
Topologically, if two spaces can be continuously deformed one into another, they may not be the “same”- take a Möbius strip and a regular strip- but they have the same number of holes if you consider a coffee cup and a doughnut to have the same number of holes. ---
**Author:** ![DPRK](https://avatars.discourse-cdn.com/v4/letter/d/4491bb/32.png) [@DPRK](https://boards.straightdope.com/u/DPRK)\ **Post date:** [March 14, 2018, 6:10pm UTC](https://boards.straightdope.com/t/does-a-drinking-straw-have-one-hole-or-two/810479/53 "2018-03-14T18:10:16Z")
> [@Musicat](#): > > An opening is not a hole. In this case, you have 3 openings, 1 hole. Isn’t that 2 holes? I could be wrong, but then you should show me how to deform it into a doughnut (rather than a 2-holed doughnut). ---
**Author:** ![TruCelt](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/trucelt/32/523_2.png) [@TruCelt](https://boards.straightdope.com/u/TruCelt)\ **Post date:** [March 14, 2018, 6:14pm UTC](https://boards.straightdope.com/t/does-a-drinking-straw-have-one-hole-or-two/810479/54 "2018-03-14T18:14:30Z")
Neither. It is a solid torus. Even mathematical experts can be found describing a torus as a ring with one hole, but that is incorrect. The torus is solid, it just happens to describe and inner area which is not fully encased. If there are holes in your straw, it won’t work unless they are below the surface of the liquid. ---
**Author:** ![eschereal](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/eschereal/32/18939_2.png) [@eschereal](https://boards.straightdope.com/u/eschereal)\ **Post date:** [March 14, 2018, 6:26pm UTC](https://boards.straightdope.com/t/does-a-drinking-straw-have-one-hole-or-two/810479/55 "2018-03-14T18:26:00Z")
> [@DPRK](#): > > Topologically, if two spaces can be continuously deformed one into another, they may not be the “same”- take a Möbius strip and a regular strip- but they have the same number of holes if you consider a coffee cup and a doughnut to have the same number of holes. Not necessarily. A hole means that the surface is not simply-connected. On a surface that is simply-connected, there is no place where you could draw a closed curve that cannot be shrunk to a point by traversing the surface. I bought a cup of coffee at a machine in the store the other day. The cup that it delivered to was a paper cylinder with no handle, which qualifies, by purposed use, as a coffee cup. There was no part of that surface that could not be described as simply-connected. It had no hole. ---
**Author:** ![Musicat](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/musicat/32/20189_2.png) [@Musicat](https://boards.straightdope.com/u/Musicat)\ **Post date:** [March 14, 2018, 6:35pm UTC](https://boards.straightdope.com/t/does-a-drinking-straw-have-one-hole-or-two/810479/56 "2018-03-14T18:35:03Z")
> [@DPRK](#): > > Isn’t that 2 holes? I could be wrong, but then you should show me how to deform it into a doughnut (rather than a 2-holed doughnut). I was referring to Mangetout’s “drill 3 times into a solid object, meeting at the center” concept. The meeting at the center would not create another hole, nor opening. Topologically, there would be only one interior passage (hole), but 3 ways to enter it from the outside (openings). ---
**Author:** ![DPRK](https://avatars.discourse-cdn.com/v4/letter/d/4491bb/32.png) [@DPRK](https://boards.straightdope.com/u/DPRK)\ **Post date:** [March 14, 2018, 6:47pm UTC](https://boards.straightdope.com/t/does-a-drinking-straw-have-one-hole-or-two/810479/57 "2018-03-14T18:47:00Z")
That’s the one I meant, and I think it is homotopically equivalent to a figure-eight. Admittedly, I pictured this in my head and haven’t tried to write down a mathematical proof or anything like that. ETA these solids don’t have an “inside”, just a connected complement (“outside”) ---
**Author:** ![Hari\_Seldon](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/hari_seldon/32/5173_2.png) [@Hari\_Seldon](https://boards.straightdope.com/u/Hari_Seldon)\ **Post date:** [March 14, 2018, 9:12pm UTC](https://boards.straightdope.com/t/does-a-drinking-straw-have-one-hole-or-two/810479/58 "2018-03-14T21:12:13Z")
Speaking _ex cathedra_, the first homology group is Z. Therefore one hole. Although it is true that a solid donut has one hole, a torus, the surface of the donut, has two and the homology group is Z^2. ---
**Author:** ![eschereal](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/eschereal/32/18939_2.png) [@eschereal](https://boards.straightdope.com/u/eschereal)\ **Post date:** [March 14, 2018, 9:23pm UTC](https://boards.straightdope.com/t/does-a-drinking-straw-have-one-hole-or-two/810479/59 "2018-03-14T21:23:02Z")
A properly made donut has thousands of holes. ---
**Author:** ![jtur88](https://avatars.discourse-cdn.com/v4/letter/j/e9c0ed/32.png) [@jtur88](https://boards.straightdope.com/u/jtur88)\ **Post date:** [March 15, 2018, 12:51am UTC](https://boards.straightdope.com/t/does-a-drinking-straw-have-one-hole-or-two/810479/60 "2018-03-15T00:51:15Z")
Do I get to vote “no holes”? Its a flat object curved. Like a toilet paper roll, which is a flat piece of cardboard with opposite edges joined. No holes. [Previous page](https://boards.straightdope.com/t/does-a-drinking-straw-have-one-hole-or-two/810479.md?page=2) [Next page](https://boards.straightdope.com/t/does-a-drinking-straw-have-one-hole-or-two/810479.md?page=4)