360 Analysis Of The Great Straw Debate: How Many Holes a Straw Has!

Jing Hu
7 min readApr 2, 2023

Just like any other evening, Klaas and I were chatting during afternoon tea, sharing the complaints of our week at work.

We then stumbled upon a classic straw debate: how many holes does a straw have? If you’ve ever fallen down a Reddit rabbit 🐰 hole, you’ll know exactly why we just had to share this ri-diculous thread about the hole-y-ness of straws!

This topic of “how many holes does a straw have?” is not new. One of the earliest online references to this question dates back to August 2001, on the Straight Dope Message Board. In this post, a user asks whether a straw has one or two holes, and several users provide their opinions and arguments on both sides of the debate. Another early reference is a blog post on The Math Less Traveled from August 2007. The author presents the question of how many holes a straw has as a mathematical puzzle and discusses various arguments and perspectives on the topic.

I started this article by wanting to summarize the opinions on various platforms and some academic arguments in order to reach a conclusion. However, I was drawn into a deeper hole by analyzing the extended questions. For example, what happens if you “keep cutting a straw in half,” “connected both ends of a straw and make it like a donut,” or “a straw falls into a black hole”?

If you have never came across this debate, here are some highlight from my ongoing straw conversation with ChatGPT.

Team Basic Thinkings

One Hole

It’s one hole, as there’s nothing in between.

It has one hole, but two entrances.

A straw has one hole, as it’s topologically equivalent to a doughnut or a coffee cup.

Definitely one hole, since a hole needs two ends to be a hole…

Team Two(+) Holes

There are two holes, as there’s one single column. Think about it… if you’re looking at the opening of a pipe, a very long pipe with the other end miles away, you are looking at a hole. The opening at the other end is part of the same system, but it’s a distinct and unique hole. When you look at the hole in front of you, you are not looking at the same hole that is miles away.

Team Pro

Topology

The number of holes in a straw depends on the topological perspective. Assuming that the straw is a simple, closed surface with no self-intersections, it has one hole. This is because the straw can be thought of as a tube-like surface with an outer boundary (the rim of the opening) and an inner boundary (the inner rim of the opening), which forms a single hole. The Euler characteristic of such a surface is χ = V — E + F = 0–0 + 1 = 1, where V is the number of vertices (points), E is the number of edges, and F is the number of faces. Therefore, the straw has one hole.

Function

The number of holes in a straw depends on its function or purpose. For example, if the purpose of the straw is to allow liquid to flow through it, then the straw has only one hole (i.e., the through hole). However, if the straw is being used as a musical instrument, then it may be argued that the straw has two holes (i.e., one at each end).

Linguistic

The number of holes in a straw depends on the linguistic interpretation of the word “hole.” It simply comes down to differences in colloquial language and regional dialects. For example, some people may refer to each end of the straw as a “hole,” while others may use different terms, such as “opening” or “entry point.”

Now that you have an idea of the answers to the original question “How many holes does a straw have?”, why don’t we complicate things even further? Let’s extend this philosophical topic into more questions that have absolutely no use to our civilization.

Let’s Take It To An Extreme Shall We?

Here are the three statements ChatGPT found that I think are really fascinating! So I have decided to turn them into questions and try to see what answers I can find.

  1. “A straw has one hole, but if you put a bendy straw in a circle, does it become a doughnut? #deepthoughts” (source: Instagram)
  2. “A straw has one hole, but if you put it in a black hole, it becomes zero holes. Science.” (source: Reddit)
  3. “A straw has one hole, but if you cut it in half, it has two halves of a hole. Checkmate, one-holers.” (source: Twitter)

A straw has one hole, but if you put a bendy straw in a circle, does it become a doughnut?

A bendy straw bent into a circle can be viewed as a surface with one hole, which is topologically equivalent to a torus, or a doughnut. This is because a circle with a hole in the middle can be stretched and deformed into a torus without tearing or gluing. If you connect both open ends of a straw to form a loop or a circle, it can also be viewed as a torus, with one hole. So, you could argue that a bendy straw connected into a loop or a circle has one hole, just like a doughnut!

A straw has one hole, but if you put it in a black hole, it becomes zero holes?

If you were to put a straw into a black hole, it would be stretched and ultimately destroyed due to the strong gravitational forces. The concept of “holes” in topology refers to topological properties of surfaces, and not to physical properties like information preservation or destruction.

However, in the context of a topological discussion, we can consider the straw to be a surface with one hole, regardless of its ultimate fate in a black hole. This is because the number of holes is a topological property that is determined by the way the surface is connected and the number of “handles” or “cavities” that it has, and not by its physical properties.

So, even if the straw were to be destroyed in a black hole, it would still be a surface with one hole from a topological perspective.

How Many Holes A Straw Has If You Keep Cutting It In Half?

This depends on:

  1. if the two ends of the straw are parallel (whether there is a pointy end) and perpendicular with the open ended cylinder
  2. how you cut the straw
  3. do you keep all the parts of the straws you cut?
  4. whether this discussion is from topology or geometry point of view

For the sake of keeping this discussion basic, yes, you read it right. Let’s make some assumptions:

  1. both ends of the straws are parallel and perpendicular with the open cylinder,
  2. the cuts are also always parallel to the straw ends + perpendicular to the open ended cylinder
  3. one of the halfs is always thrown away

Before we continue, you’d want to know how topology and geometry define circle differently. I’m far from being a topology or geometry expert, with the help of GPT 4, I got the following. A circle is considered a 1-dimensional object in topology but a 2-dimensional object in geometry:

From a topological perspective, each time the straw is cut in half and one half is discarded, the resulting object has one fewer hole and its genus is decreased by one. At the limit, the resulting object is a collection of circles, each of which has one boundary component and can be viewed as a 1-dimensional object with no holes.

From a geometric perspective, the straw is a 3-dimensional object. When it is cut in half and one half is discarded, the resulting object is still a 3-dimensional object with a hole (a cylinder with one end closed and one end open). As the process is repeated and the pieces become smaller, the objects will eventually approach a collection of circles, each of which can be viewed as a 2-dimensional object with one hole.

“The Great Straw Debate: Seeking Expert Insights on How Many Holes a Straw Has!”

In conclusion, the debate over whether a straw has one or two holes is a philosophical one, dependent on the definition of a hole and the perspective from which it is viewed. From a topological perspective, we have seen that a straw has one hole, while from a functional or linguistic perspective, it may have two or more. But, there could be other viewpoints and analyses that we haven’t considered.

If you are an expert in geometry, topology, or linguistics and have any thoughts about our analysis, we would love to hear from you! Please feel free to reach out to us and share your insights. In the meantime, let’s keep the conversation going and continue to ponder the absurd questions that arise from this seemingly simple topic. Cheers to sipping and debating!

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Jing Hu

IT Product Leader by day, Scientist and Gamer by night. Writer in between, who tries to make tech fun and games serious!