Does a Straw Have One or Two Holes? The Final Answer

In this video I tackle one of the most controversial questions ever asked. How many holes does a straw have, 1 or 2? I talk about the philosophy of holes and why holes are so weird and what causes so many people to disagree about this question.

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[TheActionLab]

Wait...can a hole have a hole in it? Also, share this video so I get a bigger sampling size for my poll.

[kyrylobohdanenko]

The question "what is the definition of a hole?" was the first thought in my mind after seeing the poll earlier this week. As I am an kind of engineer myself, you can guess my answer.

[CrazyNerdInventor]

OK I will end this argument for good, here goes.

For the cup, I argue that a hole can be mathematically described as a void that is present and in one or more cross-sectional 2D plains perpendicular to the hole in any 2D or 3D object. This means that multiple holes in the sides of a cup cannot be a part of the same hole that twists around as there is no physical object to take a cross-sectional 2D plain from to see the hole in (the hole must be completely enveloped, so a 'c' or 'u' shape does not count). In addition to this, two points create a straight line. So if only two parts have a cross-sectional 2D plain that shows a hole, the hole must be straight, so it cannot bend around a cup, but it can go straight through the middle of the cup and remain as one hole. However A bent pipe has one hole. A circular radius of a bend can be a described as an infinite number of lines making up an infinite amount of corners. Because an infinite amount of cross-sectional 2D plains can be taken from every part of the hole, the holes in the cross-sectional 2D plains can be considered to be part of the same hole. Therefore, a straw, bent or not has one hole but multiple holes in a cup cannot bend and twist around it to be a single hole.
Case closed.

Damm that is the smartist thing I have said in a long while.

[yura]

If you just touch a straw with your fingers, you'd think it has two holes. But if you really understand what's going on inside, you would figure out that what you touched is the two sides of the SAME hole.
I think the straw has two holes on its SURFACE and one through hole in its VOLUME.
Probably that's why people cannot agree - some think about volume, and some about the surface.

[Kryptic]

'forget about philosophy, let's get into science and math'
'forget about logic, let's get into logic and logic'
okay.

[DynamicFortitude]

T-shirt as a 3 dimentional "thick" object has three holes (the mathematical genus is 3), but if we think of it as infinitely thin 2 dimentional surface, it has four seperate edges. Similarly for straw: if it has "thick" walls, then genus is 1 (one hole), but if it has infinitely thin walls, then we have two seperate edges.

[billbaker]

A the number of holes in this context is based on what can be viewed on a plane. If you were viewing a picture of the object (straw) you could only see one hole or zero if viewed from the side. Without something like a reflection or visual distortion you cannot see two holes so we say it has one. This is how the term hole is commanly used. A straw has one hole, but a shirt has four. A straw bent into a U shape has two holes because that is what can be observed on a plane. This breaks down when you are describing an unexpected hole. When you pierce a straw, bucket, or even a shirt you say the item has a hole in it. You ignore the original hole(s).
This is my theory but it may be full of holes.

[dld]

I think it's a single hole. If you drill A SINGLE hole in a wall between two rooms in the house; it's a single hole thru, not two holes in a wall of two separate rooms. A hole have two ends (even if it's a blind, through or interrupted); it means it have a start point ("the edge of the hole") and an end point ("the bottom" or "the other edge" if it's a THROUGH ) or vice versa ( the begining of the hole with no edge and the another end with, or without an edge; imagine a hole sealed at both ends). There are spherical or tubular or other regulated or unregulated shapes of holes. A fountain carved in the ground is considered as a single hole, and a tunnel carved in the mountain (ground too) is considered a single hole too. You can consider a tunnel carved from both sides of the mountain and united at a point in the middle or not, two different holes/tunnels? A hole have a host (wall, glass, wood, groung, etc.) no matter how thick or thin is the material.

[TheKillingThrow]

Your answer is right from an engineering perspective but wrong in topology.

A straw has zero topological holes and two boundaries.

It is not a 1-hole object.
It is a surface with no true holes (in the topologist’s sense), but two open ends.

Although, if you were to compress a straw, it would look like a ring. It wouldn’t actually be a true ring because there are still boundaries, the edges of the cylinder and the only way to form a ring, would it be to bend the edges of the cylinder which is against the rules of topology.

There are very few channels that talk about topology. Please make sure you’re talking about it right so you don’t mislead the masses that blindly parrot everything they hear.

Tl;Dr a straw has zero holes(genus=0) and two boundary components (boundary=2)

[Rogue_]

Me: *Clicks video* "Sounds interesting.
Also me: *Finishes video* " What's a hole?"

[joeljohn]

A cup is a blind hole so if we put a hole in it can be called 2 holes but we only do if the size of the end and start differ and in a straw the size of the hole at both ends are same so it's a single hole. So basically if we consider a hole as one and the start and the end are the same it's a single hole and if they are different they are different.

[ZOMBIEHEADSHOTKILLER]

a hole is an enclosed void. a straw has one hole, that hole has 2 ends.
when you make one hole connect to another hole, they are both individual holes, and a singular hole, the same way one moose, or multiple moose, are all still called moose.

[nunziomatera]

I think straws have two holes because of how they're made.
At the beginning of the process melted plastic is extruded through a screw and at that moment it just has a hole.
But then it's cut to make the straw, making then another hole.
I think that numbers of holes depends on how an object is initially made.
If the straw was directly made without the necessity of cutting the plastic than I would have said that it had just one hole.

[nerys]

its pretty easy to me. its defined by the opening in a plane. a straw has 2 holes. each end forms a plane and those planes each have a hole in them. one on each end.

if you treat the two ends as a whole you are no longer talking about a hole but the theoretical tube/cylinder defined by the constraints of the holes.

Engineering is wrong. they are "simplyfying" the fact that they have different terms for each type is telling.

2 opposite blind holes. how many holes? well 2. so now remove the inconsequential material from the 2 blind holes forming a through hole ? now how many.

where did the other hole go? no where. its still their. each "face" that is penetrated has a hole. the "void" formed by connecting the 2 holes together through the 2 faces forms another shape (in this example a cylinder)

so in engineering terms a through hole is a cylinder connecting two face holes. if it was as simple as its a hole and only one they would not need seperate terms for each :-)

the confusion is you confusing holes with the virtual shapes "formed" by the holes. (cavity tube cylinder etc..)

a straw has 1 virtual cylinder inside it. it has 2 holes. so think of holes as OPENINGS. like a doorway.

if I put a doorway on each end of a cylindrical room LITERALLY a "straw" you can walk through.

how many doorways or "openings" does the room have? it has 2.

so how many openings or "holes" does the straw have? 2.

[RandomActsOfRandom]

If you say the straw has two holes, then anything with a perceived 1 hole in it actually has two holes. The only difference is the length between them. A straw having 7 or 8 inches between the two holes. Even when he put a hole punch in the paper. Just one hole punch is actually two holes. Even if the the distance between them is only as long as the width of the paper. So by that logic, nothing ever has just one hole in it.

[nabeelchudasama]

Honestly, it all depends on how you define a 'hole.' If we're thinking of a straw as a tube (which, it totally is), then it's basically like a mini tunnel. And do we call tunnels two holes? Nah.

Now, if you're the type who calls a donut 'one hole, ' That completely makes sense here too but its different from a tube. Do we consider our mouth and butt to be two separate holes, or just… well, one really long hole with different exits? Our two nostrils are connected inside the nasal cavity, is that just one hole then, or two?

I guess its all about perspective.

[Likahing]

my opinion: A straw has two holes. if you cut the straw short enough, shorter than the diameter of the hole, then it has one hole

[kingoftheperforations]

I would like to argue that the word hole comes from the german word hohl, which means hollow. whole is then probably derived from the german word voll, which means full. so if a hole is a hollow then a straw has only one hollow. however we can not confuse a hole with an opening. a straw has one hole with two openings, I'd say. Cheers.

[jeremygrecte]

If a straw had two holes, then a shirt would have six holes: one at the neck, one at the bottom, one at the start of the left arm, one at the end of the left arm, one at the start of the right arm, and one at the end of the right arm.

[mediumfast]

A straw doesn't have any holes. A hole is what happens when material is removed from a solid item, like the ground, a piece of wood, or a sheet of paper. But a straw is formed around a solid object that is then removed, thus creating a cavity. So straws are tubes, which have a cavity, not a hole. If you drilled a hole down a rod, then the tube would have a cavity which is a hole. A hole isn't just an absence of material, like you implied. It is the product of specifically removing material, not adding material around empty space. If it was, then a soccer ball would have a hole, and it clearly doesn't (Obviously I am excluding the valve for air). Also by this same principle, a shirt doesn't have any holes, or at least it doesn't start out with any holes lol.